Urticaria. An immunofluorescence and histopathology study

Fourteen randomly chosen patients with "garden variety" urticaria were studied for the presence of vasculitis and immunoglobulins and complement. Results of direct immunofluorescence (DIF) of the involved skin were negative, although two patients had immunoglobulins and complement demonstrable in the cytoplasm of the epidermal cells. Results of DIF of uninvolved skin were also predominantly negative. Findings from serum samples tested by indirect immunofluorescence (IIF) were negative, except for one positive in low titer (1:10, the basement membrane zone). Serum C3 and C4 levels were normal in five patients, both levels were low in two, and the C4 level was low in one patient. No skin-reactive immunoglobulins were found in these three patients by DIF or IIF. The ESR was measured and found to be elevated in four patients. Results of immunofluorescence proved negative in these cases. Of the 12 patients studied by hematoxylineosin staining to determine histology, none exhibited vasculitis. We believe that vasculitis with antigen-antibody reactions is not the rule in "garden variety" urticaria.