Production of a histamine-releasing lymphokine by antigen- or mitogen-stimulated human peripheral T cells.

Human peripheral blood leucocytes (PBL), cultured in the presence of mitogen or antigen, yielded supernatants which contained a factor with histamine-releasing activity (HRA). This factor, analogous to the putative lymphokine HRA described by Thueson et al. (1979a), was shown to promote the rapid release of histamine from PBL preparations containing basophils. HRA production by PBL in response to co-culture with the skin test antigens Candida and SK-SD was shown to reflect the in vivo immune status of the PBL donor. Experiments with isolated cell populations from PBL implicated T cells as the prime source of HRA, production of the factor being macrophage-dependent. HRA activity failed to synergize anti-IgE-mediated histamine release, and was not species-restricted.