Circulating immune complexes in patients with atopic allergy

Abstract

Sera from 49 patients with atopic allergy were tested for the presence of circulating immune complexes by the sensitive, quantitative C1q [q fragment of complement component 1] assay. Compared to 25 normal individuals the atopic patients had significantly higher mean values of C1q reactive material, expressed as C1q inhibition values. The highest mean values were seen in the group (21 patients) who were on long term maintenance immunotherapy for 5 or more yr. When positive sera were fractionated by ultracentrifugation on sucrose density gradients, the C1q reactive material was found in intermediate (7S-19S) and heavy (> 19S) regions. The heavy material contained Ig[immunoglobulin]M and IgG. The IgG antibodies known to be produced by chronic hyposensitization procedures in allergic individuals may circulate in the serum as antibody-allergen immune complexes and could carry out their blocking action in this form.