EVIDENCE FOR HISTAMINE UPTAKE BY MURINE HEMATOPOIETIC PROGENITORS

Based on previous evidence for a role of exogenous and endogenous histamine, we have examined whether this amine can effectively interact with hematopoietic progenitors. We show that tritiated histamine is retained preferentially by bone marrow cells as compared with peritoneal, thymic or spleen cells. Cells interacting with histamine copurify with progenitors in the low density bone marrow fraction. Among this cell population, 5% are labeled as assessed by autoradiography. The characteristics of histamine retention by these cells are consistent with active uptake rather than binding to a known receptor since (a) it is almost completely abrogated at 4 degrees C, by sodium azide or chloroquine, (b) histamine is internalized, and (c) relatively high concentrations of classical receptor antagonists are required to inhibit histamine retention by bone marrow cells.