Antiphospholipid (Hughes') syndrome in African-Americans: IgA aCL and aβ2 glycoprotein-I is the most frequent isotype

Abstract

Antiphospholipid (Hughes') syndrome (APS) has not been reported in African-Americans (A-A) as frequently as in other ethnic groups. We describe eight A-A female patients with APS, including two cases of primary APS (PAPS), four with APS secondary to systemic lupus erythematosus (SLE), one with Sjögren's syndrome, and one with overlap connective tissue disease (CTD). Their mean age was 34 y (range 24-47 y). Patients were followed for a mean of 6 y (range 0.3-11 y). During follow up, both anticardiolipin (aCL) and anti-beta2glycoprotein-I (abeta2GPI) antibodies were measured in stored sera by enzyme-linked immunosorbent assay (ELISA). IgA was the most frequent isotype of aCL and abeta2GPI, and co-occurred with the IgM isotype in three of four patients with neurologic manifestations.

Which are the Best Biological Markers of the Antiphospholipid Syndrome?

“…An important point is the ethnic origin in the distribution of isotypes. It has been shown that IgA is the dominant isotype in Afro-Caribbeans [95], and also in Afro-Americans [96]. However IgA aCL are often present at low or moderate titres [92], and they are sometimes transient.…”

FcαRI (CD89) Alleles Determine the Proinflammatory Potential of Serum IgA

“…Although the mean IgA1 and total IgA in samples from SLE patients are significantly higher than those from the normal population (50), IgA Abs have received little attention in SLE. IgA anti-Ro/SSA, anti-La/SSB, anti-cardiolipin, and anti-␤ 2 -glycoprotein-I autoantibodies are present in the serum of patients with SLE, Sjogren's syndrome, and anti-cardiolipin syndrome (45,51,52) and, very recently, reports indicate that not only EBV seropositivity but also a specific IgA Ab against EBV are associated with SLE patients (46,53). The reports of IgA autoantibodies and IgA anti-EBV seropositivity suggest a provocative and perhaps underappreciated link in which a more activating host response to IgA might influence an autoimmune and inflammatory response.…”

Ethnicity and APS

“…Initial studies have suggested that IgA aCL help to identify some patients as risk for thromboses [3,21,24], but to date relatively few clinical studies have been done that include IgA aCL. Genetic risk factors for aPL and APS especially MHC alleles, have been studied in several ethnic and geographic populations [25], but no clear evidence has emerged that ethnicity has a significant role in causing aPL.…”

“…A few of these studies are listed in the bibliography [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. aPL appear to occur in all populations studied, with some variations noted in frequency of occurrence.…”