Establishment of two distinct anti-cardiolipin antibody-producing cell lines from the same individual by Epstein-Barr virus transformation.

Two anti-cardiolipin antibody (ACA)-producing cell lines were established, using Epstein-Barr virus transformation followed by a repeated cluster-picking from the same individual with antiphospholipid syndrome who had a history of 8 consecutive fetal losses and deep venous thrombosis. Characterization of the two ACAs derived from these cell lines revealed that one (Ab-019, subclass IgM, kappa) reacted exclusively with cardiolipin and showed strong lupus anticoagulant activity, while the other (Ab-226, subclass IgM, lambda) reacted with negatively charged phospholipids such as phosphatidylserine and phosphatidylglycerol, as well as cardiolipin. Furthermore, Ab-226 showed reactivity with human umbilical vein endothelial cells whereas Ab-019 did not. It is suggested that ACA is heterogeneous even in the same individual, and that reactivity against negatively charged phospholipids corresponds to reactivity against endothelial cell.