TRANSFORMING-GROWTH FACTOR-PI PREFERENTIALLY INHIBITS THE INDUCTION OF CYTOTOXICITY IN HUMAN T CELLS STIMULATED VIA CD28

Generally, TGF-βs are held to down- regulate the growth of immune cells and to inhibit the development of certain differentiated functions, such as the induction of LAK activity by IL-2. In the present study, the effects of TGF-β1 on the proliferation and cytotoxicity of human PBMC activated by anti-CD3 or and-CD3 plus anti-CD28 was investigated. The results demonstrated that TGF- β1 clearly inhibits the induction of cytotoxic ability in human PBMC stimulated via CD3 or CD3 and CD28 ( P<0. 01) , without significantly altering the proliferative response to these stimuli, at the tested doses of TGF-β1. Co-stimulation with IL-2 was hardly altered, suggesting that TGF-β1 action is affected by the nature of the costimulatory signals.

Keratinocytes costimulate naive human T cells via CD2: a potential target to prevent the development of proinflammatory Th1 cells in the skin

The interplay between keratinocytes and immune cells,especially T cells,plays an important role in the pathogenesis of chronic inflammatory skin diseases.During psoriasis,keratinocytes attract T cells by releasing chemokines,while skin-infiltrating selfreactive T cells secrete proinflammatory cytokines,e.g.,IFN γand IL-17A,that cause epidermal hyperplasia.Similarly,in chronic graftversus-host disease,allogenic IFN γ-producing Th1/Tc1 and IL-17-producing Th17/Tc17 cells are recruited by keratinocyte-derived chemokines and accumulate in the skin.However,whether keratinocytes act as nonprofessional antigen-presenting cells to directly activate naive human T cells in the epidermis remains unknown.Here,we demonstrate that under proinflammatory conditions,primary human keratinocytes indeed activate naive human T cells.This activation required cell contact and costimulatory signaling via CD58/CD2 and CD54/LFA-1.Naive T cells costimulated by keratinocytes selectively differentiated into Th1 and Th17 cells.In particular,keratinocyte-initiated Th1 differentiation was dependent on costimulation through CD58/CD2.The latter molecule initiated STAT1 signaling and IFN γproduction in T cells.Costimulation of T cells by keratinocytes resulting in Th1 and Th17 differentiation represents a new explanation for the local enrichment of Th1 and Th17 cells in the skin of patients with a chronic inflammatory skin disease.Consequently,local interference with T cell–keratinocyte interactions may represent a novel strategy for the treatment of Th1 and Th17 cell-driven skin diseases.

Establishment of a Human Malignant T Lymphoma Cell Line Carrying a Retrovirus-like Particles with RT Activity

We have established an IL-2 independent malignant lymphoma line (CM-1) from peripheral T lymphocytes donated by a femalc patient with nervous systcm disease, the binlogical characteristics of CM-1 cells was studied in this paper. Another T lymphocytes,such as peripheral T lymphocytes donated by a maIe patient with multiple sclerosis, could be transformed into a malignant lymphoma line by using filtered supernatant of the CM-1 cultured medium, thus the CM-2 cell line u'as estabIished. The CM-1 and CM-2 cells were transplanted by subcutaneous inoculation into nude mice, and could cause the occurrenceof typical maIignant lymphoma. The observation of eIectron micrographs suggested the existence of virions in the CM-1 and CM-2 cells, and these virions were similar toretrovirus in the ultra-structure characteristics. lt was found that this virus possesses reverse transcriptase activity. ResuIts obtained from serological assay, molecular hybridization and PCR excluded the existence of other human viruses, which were commonly usedin our laboratory. The unknown virus possesses strong transformation activity, and probably is a new retro virus. Meanwhile, the work on the clone and sequence analysis ofthis virus are being carried out.

THE ALTERNATIVE PATHWAY OF HUMAN T CELL ACTIVATION BY MONOCLONAL ANTIBODIES(A COMPARATIVE STUDY BETWEEN NORMAL INDIVIDUALS AND CANCER PATIENTS)

This paper described T cell proliferative response by an alternative pathway in normal subjects and In patients with malignant diseases. Two McAbs, Anti-CCTl and Lo-CD2-act recognizing two distinct epitopes on E-receptor (CD2) were used to costimulate PBMC. Proliferative responsiveness was measured by 3H-thymidine incorporation. It was found that 82% of 72 nonnal subjects gave proliferative response whereas only 23% of the 93 patients did. The average cpm±SD in patients with bladder cancer (118±2314), kidney cancer (1619±2719) or lymphoma (2518±4057) was significantly lower than that in normal subjects (4935±2314), (P<0.001). These results indicate that T cell proliferation through the alternative pathway was significantly depressed in patients with cancer, and this can be used as a new parameter to monitor the immune status of cancer patients.

Effects of propofol anesthesia and sevoflurane anesthesia on the differentiation of human T-helper cells during surgery

Background Surgical stress causes a helper T-cell type 2 （Th2）-dominant status and disturbs the Th1/Th2 cytokine balance. Anesthesia can suppress the stress response to surgery, therefore it may inhibit the imbalance in the Th1/Th2 ratio. In this study, we assessed if propofol anesthesia and sevoflurane anesthesia influence the Th1/Th2 cytokine balance, and which anesthesia method better attenuates this ratio.Methods Twenty-eight patients with an American Society of Anesthesiologists （ASA） physical status of I undergoing laparoscopic cholecystectomy were selected. They were randomly allocated into two groups of 14. Group 1 received propofol anesthesia by a target-controlled-infusion （TCI） pump and group 2 received sevoflurane anesthesia.Non-invasive blood pressure, heart rate, and end-expiration CO2 partial pressure were monitored during anesthesia. The depth of anesthesia was measured using the bispectral index （BIS）, and maintained between 50 and 60. During surgery we adjusted the doses of propofol and sevoflurane according to the BIS. Samples of peripheral blood were taken before the induction of anesthesia （T1）, after the induction of anesthesia （T2）, at the beginning of surgery （T3）, at the end of surgery （T4） and on the first day after surgery （D1）. Blood samples were analyzed to give the Th1/Th2 ratio and plasma level of cortisol.Results Non-invasive blood pressure, heart rate and end-expiration CO2 partial pressure were not notably different in the two groups. At T4, the percentage of T1 cells was higher in group 1 and had statistical significance （P 〈0.05）. The percentage of T2 cells was not significantly different in the two groups. At T4, the difference in the Th1/Th2 ratio was significantly different. At T3, T4, and D1, the plasma level of cortisol was lower in group 1（P 〈0.05）.Conclusion Compared with sevoflurane, propofol can preferably promote Th cells to differentiate into Th1 cells and inhibit surgical stress. Propofol may therefore be immunoprotective for such patients.

Human CD4 ＋ effector T lymphocytes generated upon TCR engagement with self-peptides respond defectively to IL-7 in their transition to memory cells

The peripheral repertoire of CD4＋ T lymphocytes contains autoreactive cells that remain tolerant through several mechanisms. However, nonspecific CD4＋ T cells can be activated in physiological conditions as in the course of an ongoing immune response, and their outcome is not yet fully understood. Here, we investigate the fate of human naive CD4＋ lymphocytes activated by dendritic cells （DCs） presenting endogenous self-peptides in comparison with lymphocytes involved in alloresponses. We generated memory cells （Tmem） from primary effectors activated with mature autologous DCs plus interleukin （IL）-2 （Tmauto）, simulating the circumstances of an active immune response, or allogeneic DCs （Tmallo）. Tmem were generated from effector cells that were rested in the absence of antigenic stimuli, with or without IL-7. Tmem were less activated than effectors （demonstrated by CD25 downregulation） particularly with IL-7, suggesting that this cytokine may favour the transition to quiescence. Tmauto and TmaHo showed an effector memory phenotype, and responded similarly to polyclonal and antigen-specific stimuli. Biochemically, IL-7-treated Tma^o were closely related to conventional memory lymphocytes based on Erk-l/2 activation, whereas Tmauto were more similar to effectors. Autologous effectors exhibited lower responses to IL-7 than allogeneic cells, which were reflected in their reduced proliferation and higher cell death. This was not related to IL-7 receptor expression but rather to signalling deficiencies, according to STAT5 activation These results suggest that ineffective responses to IL-7 could impair the transition to memory cells of naive CD4＋ T lymphocytes recognizing self-peptides in the setting of strong costimulation.

New insight into the oncogenic mechanism of the retroviral oncoprotein Tax

Human T cell leukemia virus type 1(HTLV-1),an etio-logical factor that causes adult T cell leukemia and lym-phoma(ATL),infects over 20 million people worldwide.About 1 million of HTLV-1-infected patients develop ATL,a highly aggressive non-Hodgkin's lymphoma without an effective therapy.The pX region of the HTLV-1 viral genome encodes an oncogenic protein,Tax,which plays a central role in transforming CD4+ T lymphocytes by deregulating oncogenic signaling pathways and promoting cell cycle progression.Expression of Tax following viral entry is critical for promoting survival and proliferation of human T cells and is required for initiation of oncogenesis.Tax exhibits diverse functions in host cells,and this oncoprotein primarily targets IκB kinase complex in the cytoplasm,resulting in persistent activation of NF-κB and upregulation of its responsive gene expressions that are crucial for T cell survival and cell cycle progression.We here review recent advances for the pathological roles of Tax in modulating IκB kinase activity.We also discuss our recent observation that Tax connects the IκB kinase complex to autophagy pathways.Understanding Tax-mediated pathogenesis will provide insights into development of new therapeutics in controlling HTLV-1-associated diseases.