Histamine-releasing activity (HRA) . II. Interaction with basophils and physicochemical characterization
Thueson, D.O.; Speck, L.S.; Lett-Brown, M.A.; Grant, J.A.
Journal of Immunology 123(2): 633-639
1979
ISSN/ISBN: 0022-1767 PMID: 88480 Document Number: 150777
A histamine-releasing activity (HRA) was produced by 1- to 2-day cultures of human mononuclear cells. Synthesis of HRA was augmented by addition of the mitogen concanavalin A or by antigens that commonly elicit cell-mediated immune responses. Since histamine was released from basophils by activated complement E released normally to HRA challenge. Basophils pretreated with HRA released normally to rechallenge with HRA. Release of histamine from basophils by HRA was Ca-dependent and Mg-independent. The maximal percentage of intracellular histamine was released within a few minutes after exposure to HRA. Optimal release occurred at 37.degree. C. HRA had an apparent MW of 10,000-15,000 daltons as determined by gel exclusion chromatography. HRA was relatively resistant to the effects of elevated temperature but was destroyed by trypsin and .alpha.-chymotrypsin. The effect of trypsin was prevented by soybean trypsin inhibitor. Nucleases and neuraminidase had no effect on HRA.