IGE - RECEPTOR-POSITIVE NON-B/NON-T CELLS DOMINATE THE PRODUCTION OF INTERLEUKIN-4 AND INTERLEUKIN-6 IN IMMUNIZED MICE

The phenotype and antigenic specificity of cells secreting interleukin (IL) 4, IL-6, and interferon gamma was studied in mice during primary and secondary immune responses. T lymphocytes were the major source of interferon gamma, whereas non-B/non-T cells were the dominant source of IL-4 and IL-6 in the spleens of immunized animals. Cytokine-secreting non-B/non-T cells expressed surface receptors for IgE and/or IgG types II/III. Exposing these cells to antigen-specific IgE or IgG in vivo (or in vitro) ''armed'' them to release IL-4 and IL-6 upon subsequent antigenic challenge. These findings suggest that non-B/non-T cells may represent the ''natural immunity'' analogue of CD4(+) T helper type 2 cells and participate in a positive feedback loop involved in the perpetuation of T helper type 2 cell responses.