Immunology demystified: A guide for transplant hepatologists

Liver transplantation has become standard practice for treating end-stage liver disease.The success of the procedure relies on effective immunosuppressive medications to control the host's immune response.Despite the liver's inherent capacity to foster tolerance,the early post-transplant period is marked by significant immune reactivity.To ensure favorable outcomes,it is imperative to identify and manage various rejection types,encompassing T-cell-mediated,antibody-mediated,and chronic rejection.However,the approach to prescribing immunosuppressants relies heavily on clinical judgment rather than evidencebased criteria.Given that the majority of patients will require lifelong immunosuppression as the mechanisms underlying operational tolerance are still being investigated,healthcare providers must possess an understanding of immune responses,rejection mechanisms,and the pathways targeted by immunosuppressive drugs.This knowledge enables customization of treatments and improved patient care,even though a consensus on an optimal immunosuppressive regimen remains elusive.

On the cell biology of pit cells,the liver-specific NK cells

INTRODUCTION Natural killer (NK) cells are functionally defined by their ability to kill certain tumor cells and virus-infected cells without prior

Participation of CD45,NKR-P1A and ANK61 antigen in rat hepatic NK cell(pit cell)-mediated target cell cytotoxicity

AIM Several triggering receptors have beendescribed to be involved in natural killer（NK）cell-mediated target cytotoxicity.In these studies,NKcells derived from blood or spleen were used.Pitcells are liver-specific NK cells that possess ahigher level of natural cytotoxicity and a differentmorphology when compared to blood NK cells.The aim of this study was to characterize the roleof the NK-triggering molecules NKR-P1A,ANK61antigen,and CD45 in pit cell-mediated killing oftarget cells.METHODS 51Cr-release and DNA fragmentationwere used to quantify target cell lysis andapoptosis,respectively.RESULTS Flow cytometric analysis showed thatpit cells expressed CD45,NKR-P1A,and ANK61antigen.Treatment of pit cells with monoclonalantibody（mAb）to CD45（ANK74）not onlyinhibited CC531s or YAC-1 target lysis but alsoapoptosis induced by pit cells.The mAbs to NKR-P1A（3.2.3）and ANK61 antigen（ANK61）had no effect on pit cell-mediated CC531s or YAC-1 targetcytolysis or apoptosis,while they did increase theFcγ receptor positive（FcγR+）P815 cytolysis andapoptosis.This enhanced cytotoxicity could beinhibited by 3,4-dichloroisocoumarin,an inhibitorof granzymes.CONCLUSION These results indicate that CD45participates in pit cell-mediated CC531s and YAC-1target cytolysis and apoptosis.NKR-P1A andANK61 antigen on pit cells function as activationstructures against FcγR+ P815 cells,which wasmediated by the perforin/granzyme pathway.

Effects of bone morphogenetic protein-4 on spatial memory and cholinergic expression in the dentate gyrus after fornix-fimbria transection in rats

BACKGROUND： Previous experiments have confirmed bone morphogenetic proteins （BMPs） upregulate cholinergic expression in neurons isolated from the embryonic rat hippocampus and cerebral cortex. Therefore, BMPs could be useful for treating Alzheimer＇s disease and other neurodegenerative diseases. OBJECTIVE： BMP-4 was infused into the hippocampal dentate gyrus of fomix-fimbria transected rats to test the effects of BMP-4 on cholinergic expression in dentate gyrus neurons, and to observe changes in spatial memory behavior. DESIGN： A randomized controlled animal experiment. SETTING： Department of Neurosurgery and Laboratory for Cell Biology, Institute of Geriatrics, General Hospital of Chinese PLA. MATERIALS： Twenty-seven healthy adult male Sprague Dawley （SD） rats, weighing 250-300 g, were provided by the Laboratory Animal Center of the General Hospital of Chinese PLA. Reagents： BMP-4 （B-2680, Sigma Company） and choline acetyl transferase （CHAT） antibody （AB5042, Chemicon Company） were used in this study. Equipments： a rat stereotaxic instrument （type： SN-2N, Narushige Group, Japan） and Image-prog-plus image analysis software （Media Cybernetics company, USA） were used in this study. The protocol was carried out in accordance with ethical guidelines for the use and care of animals. METHODS： This experiment was performed in the Institute of Geriatrics, General Hospital of Chinese PLA between July 2004 and March 2005. Rats were randomly divided into 4 groups： Alzheimer＇s disease group （n = 7）, normal control group （n = 5）, BMP-4-Alzheimer＇s disease group （n = 8）, and model group （n = 7）. In the Alzheimer＇s disease group, the left hippocampal fomix-fimbria of rats was transected to mimic Alzheimer＇s disease symptoms. In the BMP-4-Alzheimer＇s disease group, 1 μt L BMP-4 （10 mg/L） was perfused into the left dentate gyrus with a microinjector at 1 μ L/min. In the model group, 1 μ L saline was perfused into the same position by the same method. Twenty-eight days after injection, Morris water maze test was performed in all rats to test spatial memory. Time-to-platform and swim-path length were recorded. Immunohistochemical staining of cholinergic neurons was performed on brain sections containing dentate gyrus. The area covered by ChAT-positive cells was analyzed using an Image-prog-plus image analysis software. MAIN OUTCOME MEASURES： Area covered by ChAT-positive cells in the dentate gyrus. Time-to-platform and swim path-length. RESULTS： Twenty-seven rats were included in the final analysis. In the Alzheimer＇s disease group, the area covered by ChAT-positive cells was significantly smaller compared with the normal control group （F = 76.03, P 〈 0.01）. The area covered by ChAT-positive cells was significantly larger in the BMP-4- Alzheimer＇s disease group than in the model group （F = 35.17, P 〈 0.05）, but significantly smaller than in the normal control group （F = 40.17, P 〈 0.05）. Time-to-platform and swim-path length were significantly longer in the Alzheimer＇s disease group than in the normal control group （F =24.62 and 631.58, respectively, both P 〈 0.05）. Time-to-platform and swim-path length were significantly shorter in the BMP4-Alzheimer＇s disease group compared with the model group （F= 22.06 and 606.89, respectively P 〈 0.05）. CONCLUSION： Injection of BMP-4 into the dentate gyrus of Alzheimer＇s disease model rats alleviates central cholinergic system injury and concomitantly improves spatial memory.

A need for stratification of metastasis samples according to secondary site in gene expression studies

Comparisons of gene expression profiles between primary tumors and metastasis have revealed genes that are implicated in metastasis formation.However,gene expression studies conducted on metastasis samples from the same primary site usually do not discriminate between different secondary sites.Although the change in the expression of number of genes is expected to be common to metastasis from the same primary but different secondary sites,herein the data that point to substantial differences are presented.Furthermore,the reciprocal communication between metastatic and host cells that is influencing these differences is outlined to emphasize the need for stratification of metastasis samples in gene expression studies.