ANTIPHOSPHOLIPID ANTIBODIES IN HEART-TRANSPLANT RECIPIENTS

Antiphospholipid antibodies (aPA) are found in patients with systemic lupus erythematosus, aPA syndrome, myocardial infarction, and stroke. The presence of aPA may predict recurrent events in certain victims of heart attack and stroke. Blood samples from 105 cardiac transplant re cipients (81 men, 24 women) were tested by enzyme-linked immunosorbent assay (ELISA) for the presence of IgG, IgM, and IgA aPA to phosphatid ylserine (PS), cardiolipin (CL), and phosphatidylethanolamine (PE). Pa tients' ages ranged from 17 to 70 years (mean 51 years). Collection ti mes ranged from Day 1 to 9 years post transplant (mean 36 months). All patients received triple immunosuppressive therapy. We report our aPA ELISA results in multiples of the normal median (MoM) of the OD405 va lues calculated for 252 healthy individuals. A positive MoM is greater than the MoM that encompasses 95% of the controls; for example, above 3 MoM is considered positive for IgG anti-CL, IgA anti-PS, and CL. Ab ove 4 MoM is positive for IgG anti-PS and PE and IgM anti-PS and CL. T hirty-nine patients had Ige anti-PS (range 4.1-14.8 MoM), 63 had IgG a nti-CL (3.1-9.4 MoM), 7 had IgM anti-PS (4.1-12.1 MoM), 1 had IgM anti -CL (14 MoM), 47 had IEA anti-PS (3.1-13.1 MoM), and 58 had IgA anti-C L (3.1-11.5 MoM). in our patient population, the incidence of IgG and/ or IgA aPA was significantly higher (p < 0.001) than IgM. Few patients showed specificity for either PS, CL, or PE, and many were positive w ith more than one antibody isotype. Because aPA were elevated in these patients, we investigated pretransplant serum samples which were avai lable from 79 of the 105 recipients, and found aPA in 52 of 79 (66%) p atients before transplantation. Longitudinal studies were done in thre e patients: two had increasing IgA aPA, beginning on Days 13 and 26 po st transplant, whereas the third patient showed an increased aPA on Da y 8 but a decrease on Day 23. Studies are in progress to determine whe ther a correlation exists between the presence of aPA, immunocytochemi cal (biopsy) findings, and clinical outcome.