Immunoglobulin classes in skin basement membrane in systemic lupus erythematosus: clinical significance and comparison with classes of serum anti-DNA antibodies.

Biopsies of apparently normal skin were obtained from 30 unselected patients with systemic lupus erythematosus. The immunoglobulin class distribution of the immune deposits at the dermal-epidermal junction was determined in order to assess associated disease patterns and to investigate the possibility that the immunoglobulin classes in the skin were an indication of the classes of serum anti-native DNA antibodies. Biopsy specimens containing IgG deposits were obtained from 10 patients with more active disease and a greater incidence of glomerulonephritis than those patients with only IgM deposits or negative biopsies. However, in this unselected group of patients the immunoglobulin class of the immune deposits did not necessarily indicate the class of serum anti-native DNA antibodies. Therefore biopsy of clinically uninvolved skin will not always identify SLE patients with an immunological restriction to IgM antibody production.