Interleukin 3 induces histamine synthesis in the human hemopoietic system.

Recombinant human interleukin 3 (rhIL-3) induces an increase in histamine production by human bone marrow, fetal liver, and cord blood cells. This phenomenon, already significant after 3 days of incubation, is strikingly enhanced following either enrichment in immature cell subpopulations or CD8+ cell depletion. It results from an increase in histamine synthesis because of 1) the low level of histamine cell content before any incubation, 2) the parallel increase in both extra- and intracellular histamine levels in response to rhIL-3, and 3) the early IL-3-induced increase in L-histidine decarboxylase (HDC; EC 4.1.1.22) activity. Moreover, rhIL-3 has no similar activity on adult peripheral blood cells, suggesting that it might be specific to the hemopoietic system.