Two Distinct T Cell Subsets, CD4+ and CD8+CD60+, and Their Cytokines Are Required for In Vitro Induction of Human Ragweed-Specific Memory IgE Responses

Abstract

CD8+CD60+ T cells (80–98% CD45RO+; 20% CD23+) are significantly increased in the blood of serum IgE+ ragweed-sensitized (RS) compared with serum IgE-nonatopic humans (p = 0.001). CD8+CD60+ T cells of the RS patients produced IL-2, IL-4, IL-10, IL-12, IFN-α. and IFN-γ, but not IL-6 or IL-13. When their PBMC were cultured with ragweed Ag (RA), peak IgE responses occurred on day 10; none was induced with non-cross-reacting or without Ag; nonatopic PBMC did not respond to any stimulant. When either CD4+ or CD8+CD60+ T cells were depleted from RS PBMC before culture with RA, no IgE responses were induced. If purified CD4+ T cells or low numbers of CD8+CD60+ T cells were added back to the depleted PBMC, IgE responses were restored. However, higher numbers of CD8+CD60+ T cells totally suppressed IgE responses. Total suppression also was obtained when RS PBMC were cultured with RA and either anti-IL-2, IL-4, IL-10, IL-12, IFN-γ (all concentrations), or IFN-α (low concentrations), but not anti-IL-6 or IL-13. Higher concentrations of anti-IFN-α potentiated IgE responses.