Increased release of histamine by anti-IgE from leucocytes of asthmatic patients and possible heterogeneity of IgE.

A study was made of the significantly increased amounts of histamine released by anti-IgE from the leucocytes of asthmatic and allergic patients, particularly in patients with a low level of serum IgE. By measuring cell-bound IgE and histamine release with anti-IgE, particularly after passive sensitization of human leucocytes, it was possible to show that serum IgE in some allergic patients differed from that in normal subjects in two respects. Firstly, it appeared to have a relatively high leucocyte binding affinity, though this could not be proved conclusively. Secondly, and more importantly, IgE of some patients could more readily mediate histamine release with anti-IgE, that is to say it had a greater efficacy. These properties should be differentiated from another feature of allergic individuals, that is the more ready releasability of histamine from the patients' own leucocytes.