Lupus band test in uninvolved oral mucosa in systemic lupus erythematosus.

In 42 patients with systemic lupus erythematosus, clinically normal oral mucosa was investigated with direct immunofluorescence technique for the presence of immunoglobulins G, A and M and complement factor C3 in the mucosal basement membrane zone (the lupus band test, LBT). Punch biopsies were performed in the posterior part of the hard palate (n = 39) or the lower labial mucosa (n = 3). The immunopathological observations were compared with clinical and serological data. The LBT was positive for IgM in 45% of the patients and trace amounts of IgM were found in another 19%. In 7 cases (17%) either IgG, IgA or C3 were found in addition to IgM and these patients all had a severe form of the disease, while the presence of IgM only was not correlated to clinical parameters.