After 2 days of culture, the CD52 expression levels of both fractions were unchanged. lymphocyte populations SAR156497 derived from peripheral blood and liver. The expression of CD52 on NK cells, especially in the liver, was lower than that of other lymphocyte populations. (n = 7, *p 0.05).(EPS) pone.0161618.s002.eps (701K) GUID:?D7D05FF9-81F3-437F-B154-4271C1875F0F S3 Fig: The phenotypes of CD52+ NK cells from the liver and peripheral blood were almost identical, instead CD52- NK cells in the liver and peripheral blood have different levels of surface marker expression. The phenotype of CD52C and CD52+ NK cell populations derived from Liver and Peripheral blood were evaluated by FCM. (A) The representative histograms of 7 impartial experiments are shown for CD52+ NK cells (upper) and CD52- NK cells (lower) in peripheral blood (dotted line) and liver (solid line). Gray solid line shows Isotype control. (B) CD69 and CD94 expression levels were significantly higher in the liver CD52? NK cells when compared with CD52- NK cells from peripheral blood. Liver CD52? NK cells expressed significantly lower amounts of CD16 and CD226. Instead, CD52+ NK cells in liver and peripheral blood had comparable phenotype. Dot shows the percentage of each surface marker on CD52- and CD52+ cells. The solid line indicates mean value in each populace and two points connected by dotted line indicate these cells are from same donor (n = 4 or 7, *p 0.05 by Students paired t-test).(EPS) pone.0161618.s003.eps (2.1M) GUID:?2C4A5E8B-A22E-4CD4-A0E2-4262CFBA5E97 Data Availability StatementAll relevant data are within the paper and its Supporting Information files. Abstract Background T-cell depleting strategies have become an integral part of immunosuppressive regimens in organ transplantation. Alemtuzumab is SAR156497 usually a humanized monoclonal antibody against CD52, a cell-surface antigen on several immune cells. It has been suggested that lymphocyte depletion increases the risk of serious infections. However, this has not been observed with short-term alemtuzumab treatment in an organ transplant setting. For induction therapy using alemtuzumab following liver transplantation, we found that T- and B-cell numbers declined rapidly after alemtuzumab therapy; however, the natural killer (NK) cell number was sustained. NK cells are important effectors SAR156497 of innate immunity. Since the effects of alemtuzumab on NK cell KLF5 functions, especially those of liver NK cells, are unknown, this study aimed to investigate this in detail. Methods To assess the effect of alemtuzumab on NK cells, samples were obtained from 7 organ donors and examined by flow cytometry using Annexin V and propidium iodide. Phenotypical and functional differences within subsets of NK cells with different levels of CD52 expression were determined by flow cytometry and cytotoxicity assays. Results CD52 expression on NK cells was lower than that on other lymphocyte subsets. The liver contained a large number of CD52? NK cells compared with the peripheral blood. treatment of liver-derived NK cells with alemtuzumab did not result in cell death. In contrast, co-incubation with alemtuzumab induced cell death in peripheral blood mononuclear cells and non-NK cells in the liver. Furthermore, CD52? liver NK cells were more cytotoxic and produced more IFN- than CD52+ NK cells after cytokine activation. Conclusion The liver contains a large number of CD52? NK cells. These cells are refractory to alemtuzumab and have strong activity. These findings indicate that CD52? NK cells persist and could protect against SAR156497 contamination after alemtuzumab-based lymphocyte depletion. Introduction Alemtuzumab is usually a humanized, rat IgG1 monoclonal antibody directed against the CD52 cell-surface antigen. CD52 is usually a glycoprotein expressed on approximately 95% of peripheral blood lymphocytes, natural killer (NK) cells, monocytes, macrophages, and thymocytes [1]. Lymphocyte depletion is usually expected to increase the risk of opportunistic infections [2, 3]. However, some studies have shown that the frequency of infectious diseases does not increase after organ transplantation [4C10]. For short-term induction therapy with alemtuzumab following liver transplantation, we found that T- and B-cell numbers declined rapidly after alemtuzumab therapy; however, the NK cell number was unchanged (S1 Fig). Comparable results were previously reported for kidney transplantation [2, 3]. Therefore, we hypothesized that NK cells have an important role in resisting microbial attack during alemtuzumab induction for several months while T-cells repopulate. A clinical examination of some patients who underwent organ transplantation revealed that NK cells reconstitute the blood earlier than T- and B-cells after alemtuzumab treatment [5, 7]. Both.