P Cell Stimulating Factor Release: A Useful Assay of T Cell Activation in vitro

Abstract

The coordinate production of multiple lymphokines by activated T cells allows the investigator a choice of assays for antigen recognition in vitro. In this paper, we examine the production of P cell stimulating factor (PSF, a lymphokine identical to interleukin 3) by L3T4+ Lyt-2–– T cell clones. PSF production is antigen-specific, la-restricted and inhibited by a monoclonal antibody to L3T4. PSF, interferon-γ (IFN-γ) and interleukin 2 (IL 2) are all rapidly secreted after antigen or mitogen stimulation. The measurement of PSF avoids problems inherent in the IL 2 and IFN-γ assays, namely absorption of IL 2 by the producer T cells and failure of the interferon assay to distinguish between interferons of the α, β and γ classes.