title: Inhibition of human T lymphocyte E rosette formation by neutrophils and hydrogen peroxide. Differential sensitivity between helper and suppressor T lymphocytes.
abstract: Co-incubation of human mononuclear cells with small numbers of autologous polymorphonuclear leukocytes resulted in a ratio-dependent inhibition of T lymphocyte rosette formation with sheep erythrocytes (SRBC). Inhibition by polymorphonuclear leukocytes was reversed with catalase, implicating H2O2 or associated products as the suppressive agent(s). Exposing T lymphocytes directly to micromolar concentrations of H2O2 also inhibited subsequent rosette formation. Inhibition was dose-dependent between 40 and 320 microM H2O2 and was not due to cytotoxicity at those H2O2 concentrations. Kinetic studies demonstrated that after exposing T lymphocytes to H2O2 a proportion of cells appeared to be relatively resistant in that they retained their ability to form E rosettes. T cell phenotype analysis of these cells showed that, in contrast to untreated T cells, H2O2-treated T rosette-forming cells were almost exclusively of the helper/inducer phenotype. Analysis with the monoclonal antibody 4B4 revealed that H2O2-resistant T rosette-forming cells contained significantly fewer 4B4-positive cells than predicted for the T helper population, indicating that H2O2-resistant T cells might be a subset of helper/inducer T lymphocytes. The interaction between H2O2 and T cells was rapid but did not lead to loss of Leu-5b binding sites. Preliminary functional analysis indicates that interleukin 2 production and phytohemagglutinin-induced proliferation by the relatively H2O2-resistant T cells is similar to untreated T cells. In contrast, H2O2-treated T cells which lost their ability to form E rosettes produced undetectable levels of interleukin 2 and proliferated poorly in response to phytohemagglutinin. Finally, mononuclear cells pretreated with H2O2 and subsequently stimulated with mitogens demonstrated a preferential expansion of the T helper population with concomitant loss of T suppressors. Our results show that, although neutrophil-released H2O2 inhibits effective interactions between SRBC and T lymphocyte sheep erythrocyte receptors, there appears to be a population of T helper cells which is relatively resistant to H2O2 both in terms of SRBC rosette formation and response to mitogens. These data suggest that at sites of inflammation phagocyte-released H2O2 could exert immunoregulatory effects on T cells by altering T cell subset survival and allowing the function of a particular lymphocyte population to predominate.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000187:drug effects; D009504:Neutrophils / Q000502:physiology*; D010835:Phytohemagglutinins / Q000494:pharmacology; D012397:Rosette Formation; D006377:T-Lymphocytes, Helper-Inducer / Q000187:drug effects / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000145:classification / Q000187:drug effects / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007376:Interleukin-2; D010835:Phytohemagglutinins; D006861:Hydrogen Peroxide; D002374:Catalase