title: Reduced lysis by CD8+ cytotoxic T cells in mixed lymphocyte reactions induced via CD4+ T cells exposed to chemically modified antigen presenting cells.
abstract: The resistance by T lymphocytes to activation by antigen (anergy) is well documented for CD4+ T-helper (Th) cells, although less is known about CD8+ cytotoxic T lymphocytes (CTL). One widely used method of inducing anergy of CD4+Th is presentation of antigen by ECDI (1-ethyl-3-(3-dimethylamino-propyl)carbodiimide)-fixed antigen-presenting cells (APCs). We report here that in murine mixed lymphocyte reactions (MLRs), a marked reduction in detected cytotoxicity (which is mediated predominantly by CD8+ CTL) occurs on day 7 if the bulk cultures are restimulated 2 days previously with ECDI-fixed allogeneic splenocytes. No differences were seen between untreated cultures on days 5 and 7, or on day 7 of cultures to which were added unfixed allogeneic splenocytes, fixed or unfixed syngeneic splenocytes, or 'third-party' allogeneic splenocytes, 2 days previously. The effect is not mediated directly on CD8+ cells, since MLRs depleted of CD4+ cells immediately prior to exposure to fixed allogeneic splenocytes fail to show reduced lysis. On the other hand, reduced lysis did occur if CD4+ cells, purified from the MLRs on day 4, were exposed to ECDI-fixed allogeneic splenocytes and then returned to MLRs previously depleted of CD4+ cells. Moreover the effect is overcome using exogenous interleukin-2 (IL-2). We propose that CD4+ cells, restimulated by a regimen shown previously to induce their anergy, can cause a reduction in CD(8+)-mediated cytotoxicity in MLRs.
authors.affiliation: Division of Life Sciences, King's College London, UK.
authors.forename: L
authors.initials: L
authors.lastname: Corlett
authors.forename: D H
authors.initials: DH
authors.lastname: Davies
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000187:drug effects* / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D017635:Clonal Anergy; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000494:pharmacology; D007376:Interleukin-2 / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D013154:Spleen / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D007376:Interleukin-2; D005022:Ethyldimethylaminopropyl Carbodiimide