[Is the histamine-producing cell stimulating factor (HCSF) identical to interleukin 3 (IL-3)?]

Since homogeneously purified Interleukin 3 can induce an increase in histamine synthesis by normal bone marrow cells (HCSF activity), it has been suggested that HCSF and IL3 could be identical. In this paper, we show evidence that HCSF activity can be obtained without any IL3 activity (determined by the proliferation of an IL3-dependent cell line). This distinction has been achieved in two different ways: (a) the physico-chemical separation of HCSF and IL3 from crude secondary MLC supernatants and (b) the spontaneous production by the P388D1 cell line of a factor possessing all the characteristics of HCSF without any IL3 activity. In addition, preliminary results show that anti-IL3 antibodies do not inhibit the increase in histamine synthesis induced by HCSF while it strongly diminishes that induced by IL3.