Evaluation of circulating immune complexes in cutaneous diseases associated with immune disorders

Several skin diseases associated with immune disorders may be related to the formation of circulating immune complexes (CIC) and their skin deposition. Sera from 20 controls and 108 patients, including: 23 psoriasis, 10 lichen planus, 30 atopic eczemas, 32 cases of leprosy, 10 vasculitis and 3 pyoderma gangrenosum were evaluated for the presence of IgG-containing CIC by the microconsumption complement test (MCT). Additionally, the presence of IgE-containing CIC by means of a polyethylene glycol precipitation and radioimmunoassay technique was evaluated in 10 patients with atopic eczema. It was found that 56.5% of psoriatic patients show moderate CIC concentrations, as well as 34% of leprosy patients, with increased levels when bacillus were detected in skin lesions, and in 90% of leukocytoclastic vasculitis. A close relationship between CIC levels and the clinical evolution of skin lesions was demonstrated in patients with pyoderma gangrenosum and lichen planus. IgG-CIC were detected in 33% and IgE-CIC in 30% of patients with atopic eczema, with the presence of both types of CIC in 2 out of 3 cases. The systematic research on CIC presence in some selected skin diseases shows that immune complexes take part, with different degrees of relevance, in the pathogenesis of all the entities.