Comparison of interferon‐γ and interleukin‐4 production by peripheral blood mononuclear cells and isolated T cells after activation with polyclonal t cell activators

Abstract

Controversial data have been reported regarding the ability of peripheral blood T cells to secrete interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) from atopic patients as compared to nonatopic healthy controls. In most of these studies, T cells in peripheral blood mononuclear cell preparations (PBMC) were stimulated with polyclonal T cell activators. Some of these activators are able to activate cells other than T cells in the PBMC preparations which may influence the lymphokine levels in supernatants of PBMC. To evaluate this, we compared the IFN-gamma and IL-4 levels in PBMC and isolated T cell preparations after activation with phytohemagglutinin (PHA), Concanavalin A (ConA), anti-CD3 plus phorbol myristate acetate (PMA), or ionomycin plus PMA. The IFN-gamma and IL-4 levels in the supernatants were calculated based on the percent T cells in the preparations. Whereas all activators induced significant IFN-gamma secretion, only ionomycin plus PMA stimulation induced large IL-4 secretion. In virtually all cases, the IFN-gamma levels calculated on a per T cell basis differed for PBMC versus isolated T cells. Whereas in some donors the IFN-gamma levels were higher in PBMC preparations than in T cells, in others it was the opposite. Similarly, in about one half of both normal and atopic donors tested, the IL-4 levels of activated PBMC were 2- to 7-fold lower than levels in isolated T cells. The data suggest that non-T cells have a significant effect on the IFN-gamma and IL-4 levels in supernatants of polyclonally activated PBMC.(ABSTRACT TRUNCATED AT 250 WORDS)