Histamine-producing cell stimulating factor (HCSF) and interleukin 3 (IL 3): evidence for two distinct molecular...

Because homogeneously purified interleukin 3 (IL 3) can induce an increase in histamine synthesis by normal bone marrow cells like histamine-producing cell stimulating Factor (HCSF), it has been suggested that HCSF and IL 3 might be identical. In this paper, we provide evidence that HCSF activity can be obtained without IL 3 activity (determined by the proliferation of an IL 3-dependent cell line). This distinction between HCSF and IL 3 has been achieved in three different ways: a) biochemical separation of HCSF from IL 3 in crude secondary MLC supernatants with description of different physicochemical characteristics of the two molecules; b) demonstration of an HCSF activity devoid of IL 3 activity in P388D1 conditioned medium, with the same characteristics as HCSF produced during secondary MLC but different from WEHI-3-derived HCSF activity resulting from IL 3; c) demonstration of a lack of inhibition of HCSF-induced histamine synthesis by anti-IL 3 immunoglobulins that clearly diminish IL 3-induced histamine production. These results demonstrate that two distinct factors (IL 3 and HCSF) promote histamine synthesis, but that IL 3 has more general effects on hemopoietic cells, whereas HCSF seems to be restricted to histamine-producing cells.