The characteristics of antigen define the cellular source and kinetics of histamine-releasing factor induced by human peripheral-blood mononuclear cells.

Peripheral-blood leucocytes from Dermatophagoides pteronyssinus- and/or Lolium perenne-allergic patients produce in vitro histamine-releasing factor (HRF) in an allergen-specific and concentration-dependent relationship. Maximum production of HRF occurred in cultures containing as little as 10-100 pg/ml crude allergen extract, although a second peak occurred at higher concentrations (10-100 micrograms/ml). While HRF was detectable in 1-hour cultures, maximal production required 24 h in culture. In contrast, HRF induced by streptokinase/streptodornase (SK/SD) was generally maximal after 1 h. Allergen-induced HRF production was almost exclusively associated with monocytes and B cells. In contrast, peripheral-blood T cells were the major source of induced HRF production in cultures containing SK/SD. Histamine-releasing cytokines are apparently produced by different cell populations, the activation of which may be dependent upon the characteristics of the stimulating antigen.