ANTIPHOSPHATIDYLETHANOLAMINE ANTIBODIES AS THE ONLY ANTIPHOSPHOLIPID ANTIBODIES DETECTED BY ELISA .2. KININOGEN REACTIVITY

Objective. To study the requirement for serum and for low (LMWK) and h igh molecular weight kininogen (HMWK) and/or HMWK binding proteins to detect antiphosphatidylethanolamine antibodies (aPE) in ELISA. Methods . Eighteen patients with aPE (9 IgG and 13 IgM) as the only antiphosph olipid antibody (aPL) detected by ELISA were assigned to 4 groups: thr omboembolic episodes (TEE) (Group I, n=6); livedo reticularis (LR) wit hout TEE, (Group TI, n=4); both LR and thrombosis (Group III, n=4); an d systemic lupus erythematosus (SLE) or primary antiphospholipid syndr ome (APS) (Group IV, n=4). All sera were analyzed in ELISA with and wi thout bovine serum and with a purified chromatographic fraction contai ning LMWK, HMWK, and HMWK binding proteins. Results, Eleven aPE were s erum dependent: mostly IgG (7/9) and some IgM (4/13). Among the 11 ser um dependent aPE, all the 7 IgG and 2 IgM were kininogen reactive. Som e serum independent IgM were better detected in the absence than in th e presence of serum in the ELISA. Conclusion, In the 18 patients, kini nogens and/or HMWK binding proteins served as a ''cofactor'' significa ntly more often for aPE IBG than for aPE IgM (p=0.007). Kininogen depe ndent aPE Ig were observed more often in patients with LR with or with out TEE (6/8) than in those with SLE or primary APS (0/4) but this dif ference merely tended to significance (p=0.06). In 2 patients, one wit h TEE, the other with primary APS, the IgM aPE was dependent on a seru m ''cofactor'' that was not kininogen.