Fig. 4: Trogocytosis by NK cells.

Natural killer (NK) cells undergo trogocytosis via interactions between NK cell receptors, such as NKG2D and KIR, and their corresponding ligands. The recruitment of these receptors to the membrane is regulated by the Src kinase pathway; thus, inhibiting Src with PP2 reduces trogocytosis. After trogocytosis, NK cells acquire ligands, such as MICA, Rae-1, or peptide-loaded MHC class I molecules, from tumor cells or antigen-presenting cells (APCs). a MICA- or Rae-1-dressed NK cells are targeted by neighboring NK cells, leading to fratricide. b NK cells acquire immune regulatory molecules such as HLA-G from tumor cells, inhibiting the proliferation and cytotoxicity of other NK cells. c The acquisition of CD9 or PD-1 directly downregulates NK cell reactivity. d NK cells acquire pMHC II and CD80/86 from dendritic cells, presenting antigens to CD4 T cells, but this antigen presentation is less effective than that of professional APCs, leading to reduced T cell responses.