Histamine and slow reacting substance (SRS) are primary mediators of anaphylactic hypersensitivity reactions. Previous studies have shown that leukocytes from allergic humans will release histamine and generate SRS when exposed in vitro to appropriate antigens. C5-peptide is a fragment of the fifth component of complement, which also induces release of histamine from human leukocytes. This study examines the possibility that C5-peptide could also stimulate SRS production. No significant synthesis or release of SRS was observed when leukocytes were exposed to concentrations of C5-peptide that induced maximal release of histamine. In companion studies, leukocytes were stimulated with concentrations of pollen antigens selected to release less histamine than when maximally stimulated with C5-peptide. In all cases, significant concentrations of SRS were detected in the supernatants of antigen-treated cells. When the leukocytes of nonallergic donors were reacted with anti-IgE or with the calcium ionophore A23187, significant quantities of histamine and SRS were released. However, reaction of these cells with C5-peptide resulted in the release of histamine without recovery of significant quantities of SRS. L-cysteine augmented the release of SRS by antigen but had little effect on the response to C5-peptide. Leukocytes simultaneously challenged with C5-peptide and antigen produced SRS in quantities equal to or greater than that recovered by antigen stimulation alone. Thus, a potent physiologic stimulus, a component of activated complement, releases significant amounts of histamine from leukocytes without SRS production and may potentiate the release of SRS by antigen.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Immunology|
|State||Published - Jan 1 1980|
ASJC Scopus subject areas
- Immunology and Allergy