The lupus band test in oral mucosa, conjunctiva and skin.

The prevalence and clinical significance of subepithelial immunoglobulin and complement deposition (the lupus band) were examined in the uninvolved sun-protected skin of the forearm, the uninvolved sun-protected lip mucosa and sun-protected bulbar conjunctival mucosa in systemic lupus erythematosus (SLE) and chronic cutaneous lupus erythematosus (CCLE). In SLE, linear deposition of an immunoreactant at the BMZ was detected in 32% (6/19) of skin biopsies; 21% (4/19) of lip mucosal biopsies and 42% (5/12) of conjunctival biopsies. There was no significant difference in the sensitivity of the test at different sites in SLE and no correlation between a positive test in skin, lip or conjunctiva and clinical mucosal involvement. In CCLE, linear deposition of an immunoreactant at the BMZ was found in 3% (1/32) of skin biopsies; 3% (1/29) of lip mucosal biopsies and 50% (10/20) of conjunctiva and clinical mucosal involvement. In the conjunctiva, IgG was present in all but one of the biopsies and was the only immunoreactant in 90% (9/10) of positive CCLE biopsies and 60% (3/5) of positive SLE biopsies. In lupus erythematosus immunoreactants may be deposited in the basement membrane zone beneath non-keratinizing mucosal surfaces of the lip and the eye as well as the skin. In CCLE, the test may be positive in conjunctiva when skin and lip are negative.