PRODUCTION OF PHAGE-DISPLAYED ANTI-IDIOTYPIC ANTIBODY SINGLE CHAIN VARIABLE FRAGMENTS TO MG7 MONOCLONAL ANTIBODY DIRECTED AGAINST GASTRIC CARCINOMA

Objective. To generate phage-displayed anti-idiotypic antibody single chain variable fragments (anti - Id ScFv) to MG7 monoclonal antibody (McAb) directed against gastric carcinoma so as to lay a foundation for developing anti-Id ScFv vaccine of the cancer.Methods. Balb/c mice were immunized i. p. with MG7 McAb conjugated with keyhole limpet hemocyanin (KLH), and mRNA was isolated from the spleens of the immunized mice. Heavy and light chain (VH and VL) genes of antibody were amplified separately and assembled into ScFv genes with a linker DNA by PCR. The ScFv genes were ligated into the phagemid vector pCANTAB5E and the ligated sample was transformed into competent E. coli TGI. The transformants were infected with M13K07 helper phage to yield recombinant phages displaying ScFv on the tips of M13 phage. After 4 rounds of panning with MG7, the MG7-positive clones were selected by ELISA from the enriched phages. The types of the anti-Id ScFv displayed on the selected phage clones were preliminarily identified by competition ELISA.Results. The VH, VL and ScFv DNAs were about 340 bp, 320 bp and 750 bp respectively. Twenty-four MG7-positive clones were selected from 60 enriched phage clones, among which 5 displayed β or γ type anti-Id ScFv.Conclusion. The anti-Id ScFv to MG7 McAb can be successfully selected by recombinant phage antibody technique, which paves a way for the study of prevention and cure of gastric carcinoma by using anti-Id ScFv.

BASIC STUDY AND PHASE I CLINIC TRIAL OF ANTI-IDIOTYPIC ANTIBODY MIMICKING NASOPHARYNGEAL CARCINOMA CELL ANTIGEN

An anti-idiotypic monoclonal antibody 2A9 (Ab2)was prepared, which mimicked the nasopharynegealcarcinoma (NPC) cell antigen defined by anti-NPC McAbFel. The abilities of 2A9's inducing humoral and cellularimmunity against NPC cell antigen were studied insyngeneic mice by inducing anti-Ab2 sera (Ab3) anddelayed-type hypersensitivity. Two periods of phasc Ⅰclinical trials were carried out, stage Ⅳ NPC patientsreceiving radiotherapy were chosen. Human anti-mouseantibodies (HAMA), anti-anti-idiotypic antibodies (Ab3),and anti-NPC cell antibodies (Ab1') were detected byELISA. TNF-α,IL-2, IFN-γ levels in sera were determinedby ELISA Kits. IL-2 mRNA expression in peripheralblood mononuclear cells (PBMC) were shown by in situhybridization. The results showed that 2A9 was safe inapplying on NPC patients and induced some humoraland/or cellular immunc responses.

Humoral immune responses induced by anti-idiotypic antibody fusion protein of 6B11scFv/hGM-CSF in BALB/c mice

Background We have previously developed and characterized a monoclonal anti-idiotype antibody, designated 6B 11, which mimics an ovarian carcinoma associated antigen OC166-9 and whose corresponding monoclonal antibody is COC166-9 （Abl）. In this study, we evaluate the humoral immune responses induced by the fusion protein 6B11 single-chain variable fragment （scFv）/human granulocyte macrophage colony-stimulating factor （hGM-CSF） and 6B 1 lscFv in BALB/c mice. Methods The fusion protein 6B 11 scFv/hGM-CSF was constructed by fusing a recombinant single-chain variable fragment of 6B11scFv to GM-CSE BALB/c mice were administrated by 6B11scFv/hGM-CSF and 6B11scFv, respectively. Results The fusion protein 6B11scFv/hGM-CSF retained binding to the anti-mouse F（ab）2＇ and was also biologically active as measured by proliferation of human GM-CSF dependent cell TF1 in vitro. After immunization with the 6B11scFv/hGM-CSF and 6BllScFv, BALB/c mice showed significantly enhanced Ab3 antibody responses to 6B11 scFv/hGM-CSF compared with the 6B11 scFv alone. The level of Ab3 was the highest after the first week and maintained for five weeks after the last immunization. Another booster was given when the Ab3 titer descended, and it would reach to the high level in a week. Conclusion The fusion protein 6B11scFv/hGM-CSF can induce humoral immunity against ovarian carcinoma in vivo. We also provide the theoretical foundation for the application of the fusion protein 6B11 scFv/hGM-CSF for active immunotherapy of ovarian cancer.

Preparation of Anti-Idiotypic Antibody against Avian Influenza Virus Subtype H9

To generate monoclonal anti-idiotypic antibodies(mAb2)against avian influenza virus subtype H9(H9 AⅣ), BALB/c mice were immunized with purified chicken anti-H9-AⅣ IgG and the splenocytes of immunized mice were fused with myeloma cells NS-1.Hybridoma cells were screened by indirect enzyme-linked immunosorbent assays with both chicken and rabbit anti-H9-AⅣ IgG as coating antigens.One hybridoma cell clone secreting monoclonal antibody against idiotypes shared by both chicken and rabbit anti-H9-AⅣ IgG was established.Experiments demonstrated the mAb2 was able to inhibit the binding of hemagglutinin to anti-H9-AⅣ IgG and to induce chickens to generate hemagglutination inhibition antibodies,indicating this anti-species-sharing-idiotypic antibody bore the internal image of hemagglutinin on avian influenza virus.Cellular & Molecular Immunology.2005;2(2): 155-157.

Nanoparticles as a vaccine adjuvant of anti-idiotypic antibody against schistosomiasis

Background The development of new adjuvants for human use has been the focus of attention. This study’s aim is to explore the possibility of using nanoparticle Ca nanoparticles (CA) as a vaccine adjuvant of anti-idiotypic antibody NP30 against schistosomiasis and its protective mechanisms. Methods Nanoparticle CA-NP30 conjugate (CA-NP30) was fabricated. BALB/c mice were immunized actively with CA-NP30 to evaluate its effects of protective immunity on mice. The serum levels of specific IgG,IgG1 and IgG2a antibodies against NP30 and the concentrations of IFN-γ and IL-4 in supernatant of splenocytes were determined via ELISA. Results Nanoparticle CA could enhance significantly the protective immunity of NP30 against infection of Schistosoma japonicum and the worm reduction rose from 36.0% (NP30 alone) to 52.6%. The serum levels of specific IgG,IgG1 and IgG2a antibodies against NP30 increased remarkably,as compared with those of the group immunized with NP30 alone. The concentration of IFN-γ in supernatant of splenocyte was drastically elevated [the groups immunized with CA-NP30 and NP30 alone were (493.80±400.74) pg/ml and (39.03±39.58) pg/ml,respectively],but the concentration of IL-4 showed no significant difference from that of NP30 alone [(27.94±9.84) pg/ml vs (27.28±14.44) pg/ml]. Conclusions Nanoparticle CA could act as a vaccine adjuvant of anti-idiotypic antibody NP30 against schistosomiasis. The mechanism could be that CA-NP30 enhances humoral and cellular immune responses in mice.

Isolation and Characterization of Recombinant Variable Domain of Heavy Chain Anti-idiotypic Antibodies Specific to Aflatoxin B_1

Some unique subclasses of Camelidae antibodies are devoid of the light chain, and the antigen binding site is comprised exclusively of the variable domain of the heavy chain （VHH）. The recombinant VHHs have a high potential as alternative reagents for the next generation of immunoassay. In particular, they might be very useful for molecular mimicry. The present study demonstrated an alpaca immunized with the F（ab＇）z fragment of anti-aflatoxin B1 mAb and developed an important anti-idiotypic （anti-ld） responses. Antigen-specific elution method was used for panning private anti-ld VHHs from the constructed alpaca VHH library. The selected VHHs were expressed, renatured, purified, and then identified by a competitive enzyme-linked immunosorbent assay （ELISA）. Our findings indicated that the VHH would be an alternative tool for haptens mimicry studies.

PREPARATION OF ANTI-IDIOTYPIC ANTIBODIES SPECIFIC FOR ANTI-HEL AND ANALYSIS OF THEIR FUNCTIONAL MIMICRY

Objective. This study is to investigate the functional mimicry by using antiidiotypic antibodies of enzymes. Methods.Monoclonal antiidiotypic antibodies against antiHEL(hen eggwhite lysozyme, HEL) antibodies were obtained by fusion of Sp2/0 myeloma cells with spleen cells of syngeneic mice immunized with monoclonal antiHEL antibodies against HELs different antigenic epitopes. Then bacteriolysis of the antiidiotypic antibodies were observed. Results.Eight hybridomas strains secreting antiidiotypic antibodies were selected and characterized. It was shown that two of eight antiidiotypic antibodies secreted by two hybridomas(1A 10 C 9 and 2A 11 C 1B 3) could mimic HEL catalytic activity to lyse Micrococcus lysodeikticus and that the catalytic effect of mixed antiidiotypic antibodies of 1A 10 C 9 and 2A 11 C 1B 3 was stronger than that of one of them, but less than HEL. Conclusion. The results demonstrated that the antiidiotypic antibodies that could mimic enzyme activity existed in the idiotype network during antienzymatic immune response.

Blockade of Rho-associated kinase prevents inhibition of axon regeneration of peripheral nerves induced by anti-ganglioside antibodies

Anti-ganglioside antibodies are associated with delayed/poor clinical recovery in Guillain-Barrèsyndrome,mostly related to halted axon regeneration.Cross-linking of cell surface gangliosides by anti-ganglioside antibodies triggers inhibition of nerve repair in in vitro and in vivo paradigms of axon regeneration.These effects involve the activation of the small GTPase Rho A/ROCK signaling pathways,which negatively modulate growth cone cytoskeleton,similarly to well stablished inhibitors of axon regeneration described so far.The aim of this work was to perform a proof of concept study to demonstrate the effectiveness of Y-27632,a selective pharmacological inhibitor of ROCK,in a mouse model of axon regeneration of peripheral nerves,where the passive immunization with a monoclonal antibody targeting gangliosides GD1a and GT1b was previously reported to exert a potent inhibitory effect on regeneration of both myelinated and unmyelinated fibers.Our results demonstrate a differential sensitivity of myelinated and unmyelinated axons to the pro-regenerative effect of Y-27632.Treatment with a total dosage of 9 mg/kg of Y-27632 resulted in a complete prevention of anti-GD1a/GT1b monoclonal antibody-mediated inhibition of axon regeneration of unmyelinated fibers to skin and the functional recovery of mechanical cutaneous sensitivity.In contrast,the same dose showed toxic effects on the regeneration of myelinated fibers.Interestingly,scale down of the dosage of Y-27632 to 5 mg/kg resulted in a significant although not complete recovery of regenerated myelinated axons exposed to anti-GD1a/GT1b monoclonal antibody in the absence of toxicity in animals exposed to only Y-27632.Overall,these findings confirm the in vivo participation of Rho A/ROCK signaling pathways in the molecular mechanisms associated with the inhibition of axon regeneration induced by anti-GD1a/GT1b monoclonal antibody.Our findings open the possibility of therapeutic pharmacological intervention targeting Rho A/Rock pathway in immune neuropathies associated with the presence of anti-ganglioside antibodies and delayed or incomplete clinical recovery after injury in the peripheral nervous system.

Autoantibodies related to ataxia and other central nervous system manifestations of gluten enteropathy

Gluten ataxia and other central nervous system disorders could be linked to gluten enteropathy and related autoantibodies.In this narrative review,we focus on the various neuro-logical manifestations in patients with gluten sensitivity/celiac disease,immunological and autoimmune mechanisms of ataxia in connection to gluten sensitivity and the autoantibodies that could be used as a biomarker for diagnosing and following.We focused on the anti-gliadin antibodies,antibodies to different isoforms of tissue transglutaminase(TG)(anti-TG2,3,and 6 antibodies),anti-glycine receptor antibodies,anti-glutamine acid decarboxylase antibodies,anti-deamidated gliadin peptides antibodies,etc.Most studies found a higher prevalence of these antibodies in patients with gluten sensitivity and neurological dysfunction,presented as different neurological disorders.We also discuss the role of a gluten-free diet on the clinical improvement of patients and also on imaging of these disorders.

Atypical Guillain-Barrésyndrome with positive anti-sulfatide,anti-GT1b,and anti-GT1a antibodies:A case report

BACKGROUND The role of diverse antibodies in mediating peripheral nerve injury in Guillain-Barrésyndrome(GBS)is becoming clearer,but positivity for multiple antibodies in one case is uncommon.To our knowledge,this is the first case involving GBS with positive anti-sulfatide,anti-GT1a,and anti-GT1b antibodies.CASE SUMMARY A 20-year-old female patient was admitted to the hospital due to weakness of limbs for 5 d,and deterioration of the weakness and muscle aches for 1 d.The patient's limbs were weak,but the tendon reflexes in the part of the limbs were normal.There was no comorbid peripheral nociception or deep sensory dysfunction.She was diagnosed with GBS and was discharged after receiving intravenous human immunoglobulin pulse therapy.CONCLUSION In this article,the clinical manifestations,neurophysiological examination,and auxiliary examination findings of a GBS patient positive for multiple antibodies were analyzed to improve the identification of the disease by clinical physicians at an early stage.

Anti-PD1 antibody and not anti-LAG-3 antibody improves the antitumor effect of photodynamic therapy for treating metastatic breast cancer

Photodynamic therapy(PDT)has limited effects in treating metastatic breast cancer.Immune checkpoints can deplete the function of immune cells;however,the expression of immune checkpoints after PDT is unclear.This study investigates whether the limited e±cacy of PDT is due to upregulated immune checkpoints and tries to combine the PDT and immune checkpoint inhibitor to observe the e±cacy.A metastatic breast cancer model was treated by PDT mediated by hematoporphyrin derivatives(HpD-PDT).The anti-tumor effect of HpD-PDT was observed,as well as CD4þT,CD8þT and calreticulin(CRT)by immunohistochemistry and immunofluorescence.Immune checkpoints on T cells were analyzed byflow cytometry after HpD-PDT.When combining PDT with immune checkpoint inhibitors,the antitumor effect and immune effect were assessed.For HpD-PDT at 100 mW/cm2 and 40,60 and 80 J/cm2,primary tumors were suppressed and CD4þT,CD8þT and CRT were elevated;however,distant tumors couldn't be inhibited and survival could not be prolonged.Immune checkpoints on T cells,especially PD1 and LAG-3 after HpD-PDT,were upregulated,which may explain the reason for the limited HpD-PDT effect.After PDT combined with anti-PD1 antibody,but not with anti-LAG-3 antibody,both the primary and distant tumors were signi-cantly inhibited and the survival time was prolonged,additionally,CD4þT,CD8þT,IFN-þCD4þT and TNF-þCD4þT cells were signi-cantly increased compared with HpD-PDT.HpD-PDT could not combat metastatic breast cancer.PD1 and LAG-3 were upregulated after HpD-PDT.Anti-PD1 antibody,but not anti-LAG-3 antibody,could augment the antitumor effect of HpD-PDT for treating metastatic breast cancer.

A nanobody-based blocking enzyme-linked immunosorbent assay for detecting antibodies against pseudorabies virus glycoprotein E

Pseudorabies(PR)is an acute infectious disease of pigs caused by the PR virus(PRV)and results in great economic losses to the pig industry worldwide.PRV glycoprotein E(gE)-based enzyme-linked immunosorbent assay(ELISA)has been used to distinguish gE-deleted vaccine-immunized pigs from wild-type virus-infected pigs to eradicate PR in some countries.Nanobody has the advantages of small size and easy genetic engineering and has been a promising diagnostic reagent.However,there were few reports about developing nanobody-based ELISA for detecting anti-PRV-gE antibodies.In the present study,the recombinant PRV-gE was expressed with a bacterial system and used to immunize the Bactrian camel.Then,two nanobodies against PRV-gE were screened from the immunized camel by phage display technique.Subsequently,two nanobody-HRP fusion proteins were expressed with HEK293T cells.The PRV-gE-Nb36-HRP fusion protein was selected as the probe for developing the blocking ELISA(bELISA)to detect anti-PRV-gE antibodies.Through optimizing the conditions of bELISA,the amount of coated antigen was 200 ng per well,and dilutions of the fusion protein and tested pig sera were separately 1:320 and 1:5.The cut-off value of bELISA was 24.20%,and the sensitivity and specificity were 96.43 and 92.63%,respectively.By detecting 233 clinical pig sera with the developed bELISA and a commercial kit,the results showed that the coincidence rate of two assays was 93.99%.Additionallly,epitope mapping showed that PRV-gE-Nb36 recognized a conserved conformational epitope in different reference PRV strains.Simple,great stability and low-cost nanobody-based bELISA for detecting anti-PRV-gE antibodies were developed.The bELISA could be used for monitoring and eradicating PR.

Antibodies Targeting a Conserved Surface Polysaccharide Are Protective Against a Wide Range of Microbial Pathogens Producing β-1-6-Linked Poly-N-Acetylglucosamine(PNAG)

The b-1-6-linked poly-N-acetylglucosamine(PNAG)polymer is a conserved surface polysaccharide produced by many bacteria,fungi,and protozoan(and even filarial)parasites.This wide-ranging expression makes PNAG an attractive target for vaccine development,as it potentially encompasses a broad range of microorganisms.Significant progress has been made in discovering important properties of the biology of PNAG expression in recent years.The molecular characterization and regulation of operons for the production of PNAG biosynthetic proteins and enzymes have been studied in many bacteria.In addition,the physiological function of PNAG has been further elucidated.PNAG-based vaccines and PNAG-targeting antibodies have shown great efficacy in preclinical research.Furthermore,clinical tests for both vaccines and antibodies have been carried out in humans and economically important animals,and the results are promising.Although it is not destined to be a smooth road,we are optimistic about new vaccines and immunotherapeutics targeting PNAG becoming validated and eventually licensed for clinical use against multiple infectious agents.

New glucocerebrosidase antibodies can advance research in the field of neurodegenerative disorders

In medical research,there are times when the introduction of a new tool can launch scientific discovery in new directions.While antibody development may be considered mundane,in the field of glucocerebrosidase(GCase)research,the dearth of validated antibodies for different applications has impeded progress in studies of disease pathogenesis and therapeutic development.The recent introduction of new,rigorously evaluated antibodies can now propel research into the link between glucocerebrosidase and Parkinson’s disease(PD)as well as aspects of the pathobiology of Gaucher disease(Jong et al.,2024).

Establishment of an indirect immunofluorescence assay for the detection of African swine fever virus antibodies

African swine fever(ASF)continues to cause enormous economic loss to the global pig industry.Since there is no safe and effective vaccine,accurate and timely diagnosis of ASF is essential to implement control measures.Indirect immunofluorescence assay(IFA)is a gold standard serological method recommended by the World Organization for Animal Health(WOAH).In this study,we used primary fetal kidney cells to establish a wild boar cell line(BK2258)that supported the efficient replication of ASF virus(ASFV)SD/DY-I/21 and showed visible cytopathic effect(CPE).Moreover,using BK2258,we established a sensitive and specific IFA for ASFV antibody detection.To standardize and evaluate the performance of this assay,we used serum samples from pigs infected with the low virulent genotype I SD/DY-I/21 and genotype II HLJ/HRB1/20,and immunized with the vaccine candidate HLJ/18-7GD,field samples,and negative serum samples.The IFA reacted with the ASFV-positive sera and displayed bright fluorescence foci.There was no non-specific green fluorescence due to cellular senescence or other cell damage-causing factors.Compared to a commercial indirect enzyme-linked immunosorbent assay(iELISA),ASFV antibodies were detected 1–4 days earlier using our IFA.The detection limits of the IFA and iELISA for the same ASFV-antibody positive serum samples were 1:25,600 and 1:6,400,respectively,indicating that the IFA is more sensitive than iELISA.The newly established IFA was highly specific and did not cross-react with sera positive for six other important porcine pathogens(i.e.,Classical swine fever virus(CSFV),Porcine reproductive and respiratory syndrome virus(PRRSV),Porcme circovirus type 2(PCV2),Pseudorabies virus(PRV),Foot-and-Mouth disease virus type O(FMDV/O),and Porcine epidemic diarrhea virus(PEDV)).This study thus provides a sensitive,specific,and reliable detection method that is suitable for the serological diagnosis of ASF.

Allogenic Stem Cell Transplantation and COVID-19 Antibodies: Mechanistic Insights and Recipient Concerns

Collecting umbilical cord stem cells is widely practiced due to its numerous benefits. Over the past decade, umbilical cord stem cells (UCSCs) have shown effectiveness in treating various conditions, such as bone pathologies, neuropsychiatry disorders, hereditary diseases, and metabolic disorders. However, factors like immunization affect the quantity and quality of cord harvesting. Studies suggest that antibodies from the mother pass through the umbilical cord to protect the infant against infections. Cleaning the umbilical cord before stem cell extraction is crucial to maintain sterility and cell integrity. Vaccinating a female donor, including for COVID-19, typically does not directly affect the stem cells. Although vaccines aim to trigger an immunological response, they generally do not affect the donor’s stem cells.

Miller fisher syndrome with positive anti-GQ1b/GT1a antibodies associated with COVID-19 infection:A case report

BACKGROUND Miller fisher syndrome(MFS)is a variant of Guillain-Barrésyndrome,an acute immune-mediated peripheral neuropathy that is often secondary to viral infections.Anti-ganglioside antibodies play crucial roles in the development of MFS.The positive rate of ganglioside antibodies is exceptionally high in MFS patients,particularly for anti-GQ1b antibodies.However,the presence of other ganglioside antibodies does not exclude MFS.CASE SUMMARY We present a 56-year-old female patient who suddenly developed right blepharoptosis and progressively worsening vision in both eyes.There were flu symptoms prior to onset,and a coronavirus disease 2019 test was positive.On physical examination,the patient exhibited bilateral extraocular muscle paralysis,weakened reflexes in both limbs,and impaired coordination.The cerebrospinal fluid examination results showed no obvious abnormalities.Bilateral peroneal nerve F-waves were not extracted.Serum anti-GD1b IgG and anti-GT1a IgG antibodies were positive.The patient received intravenous methylprednisolone(1000 mg/day),with the dosage gradually decreased.Additionally,intravenous high-dose immunoglobulin treatment was administered for 5 days(0.4 g/kg/day)from day 2 to day 6 of hospitalization.The patient’s symptoms improved after treatment with immunoglobulins and hormones.CONCLUSION Positive ganglioside antibodies may be used as supporting evidence for the diagnosis;however,the diagnosis of MFS is more reliant on clinical symptoms.

Preparation of anti-canine interleukin-31 receptor alpha polyclonal antibody and evaluation of its therapeutic efect in canine atopic dermatitis

Canine atopic dermatitis(CAD)is a prevalent genetically susceptible infammatory and pruritic allergic skin condition afecting not only the health of dogs but also the quality of life of their owners.Interleukin-31(IL-31)and interleukin-31 receptor alpha(IL-31RA)are essential for the development of pruritus in primates and mice.Hence,it is expected that inhibiting IL-31RA will be an efective approach to alleviate pruritus.The purpose of the study was to produce anti-canine IL-31RA polyclonal antibodies(anti-IL-31RA pAbs)and evaluate their efcacy in inhibiting house dust mite(HDM)-evoked pruritic responses.Dogs were immunized with antigens formed by IL-31RA recombinant short peptides coupled to BSA to produce anti-IL-31RA pAbs.The CAD model was developed by using HDM allergen stimulation,and the efects of IL-31RA pAbs on the reduction of pruritus in CAD model dogs were examined.The Canine Atopic Dermatitis Extent and Severity Index(CADESI)-4 and pruritus Visual Analog Scale(pVAS)were utilized to evaluate pruritic responses,and skin tissue samples were collected from the inguinal area for pathological assessment of skin infammatory cell infltration.The results showed that anti-IL-31RA pAbs with high titers(1:128,000)and specifcity were efectively produced.In the CAD model group,the severity of skin damage,pruritus score,infammatory cell infltration and level of infammatory factors were considerably elevated.Anti-IL-31RA pAbs relieved pruritic behavior and dermatitis in dogs compared to placebo-treated dogs.In conclusion,anti-IL-31RA pAbs efectively suppressed CAD in vivo and are anticipated to be an efective novel treatment for pruritic skin disorders such as CAD.

Human leukocyte antigen compatibility and incidence of donorspecific antibodies in pediatric liver transplant recipients

BACKGROUND Antibody-mediated rejection following liver transplantation(LT)has been increasingly recognized,particularly with respect to the emergence of de novo donor-specific antibodies(DSAs)and their impact on graft longevity.While substantial evidence for adult populations exists,research focusing on pediatric LT outcomes remains limited.AIM To investigate the prevalence of human leukocyte antigen(HLA)mismatches and DSA and evaluate their association with rejection episodes after pediatric LT.METHODS A cohort of pediatric LT recipients underwent HLA testing at Santa Casa de Porto Alegre,Brazil,between December 2013 and December 2023.Only patients who survived for>30 days after LT with at least one DSA analysis were included.DSA classes I and II and cross-matches were analyzed.The presence of de novo DSA(dnDSA)was evaluated at least 3 months after LT using the Luminex®single antigen bead method,with a positive reaction threshold set at 1000 MFI.Rejection episodes were confirmed by liver biopsy.RESULTS Overall,67 transplanted children were analyzed;61 received grafts from living donors,85%of whom were related to recipients.Pre-transplant DSA(class I or II)was detected in 28.3%of patients,and dnDSA was detected in 48.4%.The median time to DSA detection after LT was 19.7[interquartile range(IQR):4.3-35.6]months.Biopsyproven rejection occurred in 13 patients at follow-up,with C4d positivity observed in 5/13 Liver biopsies.The median time to rejection was 7.8(IQR:5.7-12.8)months.The presence of dnDSA was significantly associated with rejection(36%vs 3%,P<0.001).The rejection-free survival rates at 12 and 24 months were 76%vs 100%and 58%vs 95%for patients with dnDSA anti-DQ vs those without,respectively.CONCLUSION Our findings highlight the importance of incorporating DSA assessment into pre-and post-transplantation protocols for pediatric LT recipients.Future implications may include immunosuppression minimization strategies based on this analysis in pediatric LT recipients.

Prevalence and Factors Associated with Positivity of Antinuclear Antibodies (ANA) Patterns, Native Anti-DNA and Extractable Nuclear Antigens (ENA) Antibodies: Experience from a Laboratory in Dakar

Background: Diagnosis of autoimmune diseases (AID) is challenging, due to overlapping features with other non-immune disorders. Anti-nuclear antibodies (ANA) are sensitive screening tests but anti-deoxyribonucleic acid-antibody (anti-DNA), and anti-extractable nuclear antigens (anti-ENA) are specific for AIDs. We aimed to look at ANA patterns in our patients and correlated them with anti-ENA for proper interpretation and better patient management cost-effectively. Methods: A retrospective study was conducted over 1 year from January to December 2022 who were tested for ANA at biology medical laboratory of Pasteur Institute of Dakar. Anti-ENA and anti-DNA results were also analyzed for ANA-positive patients. Statistical analysis was performed using STATA 14.0, p Results: 216 patients were analyzed. Women predominated at 79.2% and mean age was 48 years [CI 95%, 46 - 50], with extremes of 10 and 89. Most represented age group was [41 - 60] with 38%. ANA was positive in 27 (12.5%) of patients, 59.2% of whom were strongly positive (titer of 1/1000, 1/3200 or 1/6400). The most common pattern was nuclear speckled, which was found in 77.8% of samples. Anti-ENA and anti-DNA positivity in ANA-positive patients was found respectively in 63% (17/27) and 1.4% (3/27) of the samples analyzed. Most commonly identified anti-ENA was anti-Sm 29.6%, anti-SSA 29.6%, anti-Ro-52 25.9%, anti-RNP 18.5% and anti-SSB 14.8% which was associated with speckled pattern. Association results indicated a significant relationship between both tests and between ANA titer in the anti-ENA- and ANA-positive patients (p 0.001). Conclusions: ANA, Anti-ENA and anti-DNA antibodies are essential for AIDS diagnosis. However, the testing repertoire should follow an algorithm comprising of clinical features, followed by ANA results with nuclear, mitotic, and cytoplasmic patterns, anti-ENA, and anti-DNA for a more meaningful, and cost-effective diagnostic approach.