I. Yron et al., A HUMAN MONOCLONAL IGA AUTOANTIBODY-185 12 BEHAVES LIKE AN AUTOIMMUNEANTIPHOSPHOLIPID ANTIBODY/, Clinical and experimental immunology, 97(2), 1994, pp. 187-192
A human monoclonal anticardiolipin autoantibody (ACA) of the IgA-k iso
type, designated 185/ 12, is described. The antibody was prepared from
peripheral B cells, obtained from a patient with a history of habitua
l abortion, by immortalization with Epstein-Barr virus (EBV). The anti
body displays a strong binding activity to cardiolipin and phosphatidy
l L-serine, but not to phosphatidylcholine, phosphatidylinositol, ssDN
A and dsDNA. It binds to cardiolipin in a concentration-related and sa
turable manner (K-d = 3.0X10(-8) M). This reaction is dependent upon t
he presence of bovine serum, and is fully inhibited by cardiolipin ves
icles. The 185/12 antibody exhibits different binding patterns to the
solid-phase bound cardiolipin-serum complex and to its individual comp
onents (cardiolipin and bovine serum). The B-max of 185/12 binding to
the complex (0.968 OD units) is higher than the sum of the B-max value
s calculated for each one of the complex components (0.352 + 0.179 = 0
.531 OD units). Bovine serum as well as purified beta(2)-glycoprotein
I (beta(2)-GPI) in suspension inhibit the binding of 185/12 to the com
plex. 185/12 binding capacity increases in direct relation to the risi
ng concentration of beta(2)-GPI, Collectively, these data may be inter
preted to suggest that 185/12 antibody, which is an IgA isotype, exhib
its characteristics usually attributed only to antiphospholipid autoan
tibodies (APA) of the IgG isotype, that are associated with the clinic
al spectrum of APA syndrome (APA-S). It is, therefore, possible that a
utoantibodies of the IgA isotype could play a pathogenic role, which m
ay be different from that of the IgG isotype, in the development of au
toimmune phenomena.