Monoclonal hybridoma anti-cardiolipin antibodies from SLE mice.

To determine whether the anti-cardiolipin antibodies are identical with the lupus anticoagulant and other antibodies to phospholipids and DNA, we prepared monoclonal hybridoma autoantibodies to cardiolipin from SLE-prone MRL/lpr mice and characterized their specificity. Using a somatic cell hybridization technique, we established three hybridoma clones which produce antibodies to cardiolipin (CAL-1: IgG2b, k, CAL-2: IgM, k and CAL-3: IgM, k). These hybridoma antibodies preferentially reacted with cardiolipin and phosphatidylserine, weakly reacted with phosphatidylinositol, but not with other phospholipids such as phosphatidylcholine, sphingomyelin, phosphatidylethanolamine and VDRL antigen. Two hybridoma anti-cardiolipin antibodies bound to ssDNA and were found to act as the lupus anticoagulant when mixing activated partial thromboplastin time with cephalin. These autoantibodies may prove to be good tools for elucidating mechanisms of thrombosis, thrombocytopenia, fetal loss and other related manifestations found in patients with systemic lupus erythematosus.