SKEWED DISTRIBUTION OF IGG FC RECEPTOR IIA (CD32) POLYMORPHISM IS ASSOCIATED WITH RENAL-DISEASE IN SYSTEMIC LUPUS-ERYTHEMATOSUS PATIENTS

Objective. Fc gamma receptors of class IIa (Fc gamma RIIa) occur in 2 allelic forms, with either a low (IIa-R131) or a high (IIa-H131) affin ity for complexed IgG2 and IgG3. This polymorphism might have implicat ions for the handling of immune complexes. Therefore, we determined th e distribution of the Fc gamma RIIa allotypes in patients with systemi c lupus erythematosus (SLE), with or without a history of lupus nephri tis. Methods. We studied 95 unrelated white European patients with SLE , as defined by the American College of Rheumatology criteria, 50 of w hom had a history of lupus nephritis, and 69 healthy white European co ntrol subjects. Fc gamma RIIa allotypes were determined by immunopheno typing of blood monocytes. Results. It was found that lupus nephritis was significantly associated with the ''low affinity'' Fc gamma RIIa R /R131 allotype and with the R131 allele, compared with healthy control s. No significant association was found upon comparison of groups with and without nephritis. Conclusion. SLE patients with a history of lup us nephritis have an abnormal distribution of Fc gamma RIIa allotypes. Fc gamma RIIa may well play a role in the pathogenesis of lupus nephr itis, since IIa-R/R131 SLE patients seem to have a higher incidence of developing this complication.