Research progress on trogocytosis of immune cell in transplantation immunity / 器官移植

Trogocytosis is a process of exchanging part of the membrane fragment or cytoplasmic content of cells through direct contact, and it's an interaction mechanism that exists between cells. Immune cell can obtain some characteristics of other cells through trogocytosis, and the new cells generated through trogocytosis may play an important role in the induction of graft immune tolerance. In this article, the origin and development of research on cell trogocytosis, mechanism of cell trogocytosis and biological significance of trogocytosis of immune cell were reviewed.

Extrinsic Acquisition of CD80 by Antigen-Specific CD8⁺ T Cells Regulates Their Recall Immune Responses to Acute Viral Infection

CD80 is mainly expressed on Ag-presenting cells (APCs) as a costimulatory molecule but is also detected on T cells. However, the origin and physiological role of CD80 on CD8⁺ T cells remain unclear. In the present study, we demonstrated that effector and memory CD8⁺ T cells, but not naïve CD8⁺ T cells, displayed CD80 molecules on their surfaces after acute lymphocytic choriomeningitis virus infection. Using adoptive transfer of CD80-knockout (KO) CD8⁺ T cells into a wild type or CD80-KO recipient, we demonstrated that the effector CD8⁺ T cells displayed CD80 by both intrinsic expression and extrinsic acquisition, while memory CD8⁺ T cells displayed CD80 only by extrinsic acquisition. Interestingly, the extrinsic acquisition of CD80 by CD8⁺ T cells was observed only in the lymphoid organs but not in the periphery, indicating the trogocytosis of CD80 molecules via interaction between CD8⁺ T cells and APCs. We compared the recall immune responses by memory CD8⁺ T cells that either extrinsically acquired CD80 or were deficient in CD80, and found that CD80, presented by memory CD8⁺ T cells, played a role in limiting their expansion and IL-2 production upon exposure to secondary challenge. Our study presents the in vivo dynamics of the extrinsic acquisition of CD80 by Ag-specific CD8⁺ T cells and its role in the regulation of recall immune responses in memory CD8+ T cells.

NK cells extract HLA-G1 antigen from K562-G1 cells via trogocytosis / 中华微生物学和免疫学杂志

Objective To investigate the mechanism of acquisition of HLA-G1 antigen by NK cells.Methods K562 cells stably expressing HLA-G1 antigen (K562-G1) were constructed.K562-G1 cells, K562 cells and shed HLA-G1 were respectively co-cultured with NK-92MI cells to observe the acquisi-tion of HLA-G by NK cells.To further investigate the mechanism , NK-92MI cells with blockage HLA-G re-ceptors were further co-cultured with K562-G1 cells and HLA-G1 proteins expressing on K 562-G1 cells were blocked and then co-cultured with NK-92MI cells. Acquisition of HLA-G 1 by NK-92MI cells was analyzed by flow cytometry and fluorescence microscopy .The effects of HLA-G1 expression on the cytotoxicity of NK-92MI cell were evaluated by flow cytometry analysis based on CD 107a labeling.R esults NK-92MI cells could quickly acquire HLA-G1 from K562-G1 cells in co-culture experiments .Blockade of HLA-G1 or its re-ceptors KIR2DL4 and ILT2 with specific mAbs did not affect the acquisition of HLA-G1 by NK-92MI cells. Moreover, HLA-G1 could significantly inhibit the cytotoxicity of NK cell ( P<0.01).Conclu sion NK-92MI cells acquire HLA-G1 from K562-G1 cells via trogocytosis , which is not associated with affinity be-tween receptor and ligand , extracellular domain of HLA-G1 or passive adhesion .