Variability of anticardiolipin antibody isotype distribution in 3 geographic populations of patients with systemic lupus erythematosus.

OBJECTIVE

To investigate the prevalence of anticardiolipin antibodies (aCL) and isotype distribution and their clinical associations with the features of the antiphospholipid syndrome (APS) in 3 different ethnic groups of patients with systemic lupus erythematosus (SLE).

METHODS

The study population consisted of 152 African-American, 136 Afro-Caribbean (Jamaican), and 163 Hispanic (Colombian) unselected patients with SLE. Serum samples were studied for the prevalence of aCL and isotype distribution. All aCL measurements were performed in the same laboratory by ELISA.

RESULTS

Positive results for 1 of the 3 aCL isotypes were found in 42 African-Americans (28%), 28 Afro-Caribbeans (21%), and 43 Hispanics (26%). IgG aCL was the dominant isotype in Hispanic and African-American patients, while IgA was the dominant isotype in Afro-Caribbeans. Of note, IgA aCL was found in all Afro-Caribbean patients who were aCL positive, while only 3 patients in this group had IgG aCL and 2 had IgM aCL. Clinical features of the APS were found to correlate better in Hispanics than in African-Americans and Afro-Caribbean patients with aCL isotypes.

CONCLUSION

Our data suggest the existence of ethnic differences in the prevalence and isotype distribution of aCL as well as in their clinical relevance in patients with SLE. Further studies of the role of genetic and/or environmental factors in the observed differences are required.