Human antibodies to mast cells.

This study describes a human IgG autoantibody detected by immunofluorescence, found in four out of 1410 (0·3%) mixed hospital patients' sera and which reacted exclusively with tissue mast cell (MC) granules in a non-species specific manner. No reaction occurred with blood basophils, suggesting that their granules differ from those of tissue MC. Experiments so far indicate that the antigen is in the amphophilic protein matrix of the granules. Histamine and 5HT cannot be involved since granules showed positive fluorescence following their release and commercial heparin could not absorb out the fluorescence. The antibodies did not cause MC degranulation or histamine release and antigenic determinants could not be demonstrated on the MC membrane, unlike similar antibodies produced experimentally.