CAN TESTS FOR IGA, IGG, OR IGM ANTIBODIES TO CARDIOLIPIN OR PHOSPHATIDYLSERINE SUBSTITUTE FOR LUPUS ANTICOAGULANT ASSAYS IN SCREENING FOR ANTIPHOSPHOLIPID ANTIBODIES

Antiphospholipid antibodies (APL) are detected by both ELISA and tests for lupus anticoagulants (LA). We evaluated ELISA tests for IgG, IgM, and IgA isotopes of antibodies binding cardiolipin (CL) and phosphati dylserine (PS) in samples from LA patients presenting with recurrent m iscarriages. All values were expressed in multiples of the normal medi an (MOM). In 32% (11/34) of cases, not only were all ELISA values at o r below 2.5 MOM, but the distribution of these ELISA MOM values within the normal range was similar to distribution of values from LA negati ve controls with the same history. Neither the use of PS as the antige n nor the addition of IgA assays improved the correlation of ELISA res ults with the presence of LA. ELISAs are inadequate as the sole screen ing test for these separate, but often associated, families of APL.