Histamine releasing lymphokine: preliminary evidence of membrane receptors on basophils

Histamine release induced by the lymphokine-histamine releasing factor (HRF), like IgE-mediated release is a two step event--the Ca2+-independent activation step in which HRF primes the cells for histamine release and the Ca2+-dependent histamine release. The stimulus produced by the activation step decays relatively slowly and exponentially with a half-time of 38 min. By the 'receptor desensitization' approach, HRF appears to possess specific receptors on basophils as demonstrated by its ability to desensitize the cells to itself for subsequent histamine release. Cross desensitization experiments further suggested that a close relationship might exist between any such receptors and cell-bound IgE molecules, since desensitization of cells to anti-IgE also resulted in their desensitization to HRF as well; though the reverse was not the case. Nevertheless, any such relationship does not involve binding and cross linking of cell-bound IgE molecules by HRF. The putative HRF receptors may be distinct from those proposed for macrophage migration inhibitory factor (MIF) and leucocyte migration inhibitory factor (LIF) since, unlike the latter lymphokines whose interactions with their target cells show specificity for certain simple sugars, HRF's interaction with basophils show no such specificity to any of the simple sugars tested.