title: CD3-negative lymphokine-activated cytotoxic cells express the CD3 epsilon gene.
abstract: The expression of genes encoding different polypeptide chains of the TCR-CD3 complex was analyzed in a panel of cloned MHC-unrestricted cytotoxic cells. The clones were derived from CD3+ and CD3- human PBL. After expansion in rIL-2, all clones were able to lyse the NK-sensitive target cell line K562. In contrast, lysis of fresh tumor cells was achieved almost exclusively by CD3- clones. To test whether a known TCR-CD3 complex may be involved in MHC-unrestricted cytotoxicity, total RNA from nine CD3+ and 11 CD3- clones was isolated and hybridized with DNA probes for the TCR alpha-, beta-, and gamma-chains and for the CD3 gamma-, delta-, and epsilon-chains. TCR gamma transcripts were present at high levels in CD3+CD4- CD8- clones but were undetectable in all CD3- clones. Lysis of fresh tumor cells is an activity which can be independent of the TCR alpha beta and TCR gamma complexes because the CD3- clones did not express these TCR genes. Interestingly, all CD3- clones expressed CD3 epsilon transcripts, but not CD3 gamma- or delta-transcripts. CD3- lymphokine-activated cytotoxic cells may therefore be derived from immature T cells which do not yet express a complete CD3 complex. The CD3 epsilon chain, if expressed in CD3- cells in association with other molecules, could be involved in the activation and lytic function of these MHC-unrestricted cytotoxic cells.
mesh_terms: D000954:Antigens, Surface / Q000235:genetics*; D018801:CD2 Antigens; D002352:Carrier Proteins / Q000032:analysis; D002999:Clone Cells / Q000145:classification / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D016169:Lymphocyte Function-Associated Antigen-1; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D011971:Receptors, Immunologic / Q000032:analysis; D013602:T-Lymphocytes, Cytotoxic / Q000145:classification* / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D018801:CD2 Antigens; D002352:Carrier Proteins; D007376:Interleukin-2; D016169:Lymphocyte Function-Associated Antigen-1; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic