Urticaria. An immunofluorescence and histopathology study.

Area of Science:

• Immunodermatology
• Rheumatology
• Allergy and Immunology

Background:

• Urticaria, commonly known as hives, is a frequent skin condition.
• The underlying cause of "garden variety" urticaria is not always clear.
• Vasculitis and immune complex deposition are potential, though not fully understood, contributors.

Purpose of the Study:

• To investigate the presence of vasculitis in patients with common urticaria.
• To assess immunoglobulin and complement deposition in the skin and serum of these patients.
• To determine if antigen-antibody reactions play a significant role in "garden variety" urticaria.

Main Methods:

• Direct immunofluorescence (DIF) on skin biopsies (involved and uninvolved).
• Indirect immunofluorescence (IIF) on serum samples.
• Measurement of serum complement levels (C3, C4).
• Erythrocyte Sedimentation Rate (ESR) and Hematoxylin-Eosin (H&E) staining for histology.

Main Results:

• Direct immunofluorescence of skin was predominantly negative for immunoglobulins and complement.
• Two patients showed cytoplasmic immunoglobulin and complement in epidermal cells.
• Indirect immunofluorescence of serum was mostly negative, with one low-titer positive finding.
• Serum complement levels varied, with some patients showing low C4 or C3/C4.
• Hematoxylin-Eosin staining did not reveal vasculitis in any of the 12 patients studied.
• Elevated ESR was noted in four patients, but immunofluorescence results were negative.

Conclusions:

• Vasculitis is unlikely to be the primary mechanism in most cases of "garden variety" urticaria.
• Significant antigen-antibody reactions or immune complex deposition are not consistently found.
• Further research may be needed to elucidate the specific pathophysiology of common urticaria.