Serum immunoglobulins, complements and circulating immune complexes in oral lichen planus.

Serum IgG, IgM, IgA, C3, C4 concentrations and circulating immune complexes (CIC) were measured in a series of 46 patients with oral lichen planus (LP). This investigation revealed a significant increase in the level of serum IgG in patients with oral LP as compared with 36 healthy subjects. In erosive LP, serum IgM was also elevated as compared with healthy subjects and patients with the non-erosive type. The results of this study did not support the suggestion that a humoral immunodeficiency underlies oral LP. Elevated serum level of IgM may be considered to represent secondary oral infection during mucosal erosion. The study also demonstrated a significant reduction in serum C4 in both variants of oral LP, but the C3 level was normal. A 3% polyethylene glycol precipitation (PEG-ppt) method was used, no significant amount of CIC could be detected in the patients. It is tempting to speculate that oral LP reflects an immunologic disorder in which serum IgG and C4 is disturbed. However, further investigation is needed to clarify the pathogenesis of oral LP.