Immunofluorescence studies on C1Q in mast cells.

Evidence has been obtained of deposition of complement component C1q in mast cells, by the immunofluorscence technique, using biopsy specimens from the scalp from 5 of 7 normal subjects and 14 of 17 patients with alopecia areata and also from skin lesions of 1 of 2 patients with urticaria pigmentosa studied. The fluorescence in mast cells was of a granular pattern in most instances. No deposition of immunoglobulins (IgG, IgA, IgM, IgE) or other complement components (C3, C4, C5, C9) was demonstrable in the mast cells. The specificity of the C1q deposition in mast cells was confirmed by various tests, viz., the blocking test, prerinsing of tissue sections with bovine serum albumin-containing phosphate-buffered saline, absorption test of conjugates, C1q destruction test with urea or by heating, and the Ouchterlony method.