Distribution of lupus anticoagulant and anticardiolipin antibody isotypes in a population with antiphospholipid syndrome

Objective. To analyze the distribution of lupus anticoagulant (LAC) and anticardiolipin antibody (aCL) isotypes in a population with antiphospholipid syndrome and to explore whether there is an association with the site of thrombotic episodes and the number of recurrent spontaneous abortions. Methods. Ninety-two patients (73 female, 19 male) with positive LAC and/or aCL were included as 2 groups: (1) 20 patients with secondary antiphospholipid syndrome (APS) (16 had thrombotic episodes and 4 thrombocytopenia); (2) 72 patients with primary APS (31 presented thrombotic episodes and 41 had recurrent spontaneous abortion). Results. In Group 1 seven of 20 (35%) patients with secondary APS had IgG aCL, 9 (45%) had both IgG/IgM aCL, and 2 (10%) had IgM aCL; the remaining patients had combinations of aCL isotypes. In Group 2 patients with primary APS, IgG aCL was positive in 41%, IgG/IgM mixture in 21%, and 15% of patients had combinations of the 3 isotypes. Sixteen of 20 (80%) patients with secondary disease and 37 of 72 (51%) with primary disease tested positive for LAG. Conclusion. The presence of one or any mixture of isotype of aCL with or without LAC is not associated with the site of thrombosis (venous or arterial). On the contrary, in the patients with primary PIPS, the presence of the 3 aCL isotypes plus LAC was associated with a higher number of recurrent spontaneous abortions compared to other possible combinations of aCL isotypes.