HEMATOPOIETIC PROGENITORS AND INTERLEUKIN-3-DEPENDENT CELL-LINES SYNTHESIZE HISTAMINE IN RESPONSE TO CALCIUM IONOPHORE

The calcium ionophore A23187 promotes histamine synthesis in murine bo ne marrow cells by increasing the expression of mRNA encoding histidin e decarboxylase (HDC), the histamine-forming enzyme. The cells respons ible for this biological activity copurify with hematopoietic progenit ors in terms of density, light scatter characteristics, and rhodamine retention, similar to interleukin (IL) 3-induced histamine-producing c ells. Yet, the effect of calcium ionophore is not mediated by IL-3. Th e most purified rhodamine-bright bone marrow subset contains 80% cells that respond to calcium ionophore by increased HDC mRNA expression. T his high frequency makes the involvement of one particular progenitor subset in histamine synthesis unlikely. The finding that all IL-3-depe ndent cell lines tested so far exhibit increased histamine production and HDC mRNA expression in response to calcium influx lends further su pport to this notion. Cell lines requiring other growth factors or pro liferating spontaneously lack this ability, Finally, it should be note d that IL-3-dependent cell lines do not produce histamine in response to their growth factor, It might, therefore, be suggested that the pat hway transducing the signal for increased histamine synthesis after IL -3 receptor binding in normal hematopoietic progenitors is modified in these cell lines. (C) 1996 by The American Society of Hematology.