High titres of IgM-antiphospholipid antibodies are unrelated to pathogenicity in patients with non-Hodgkin's lymphoma.

Heterogeneity in the mechanisms of coagulation may contribute to an increased thrombotic risk for patients with malignancies. The coincidence of malignancies and antiphospholipid antibodies (aPL) have been described in several important epidemiological studies. The pathological significance of aPL in patients with malignancies is, however, still unclear. In this study, we investigated the clinical manifestations of four patients with elevated IgM-aPL titres lying outside the region signifying 95% of normal cases and with a history of non-Hodgkin's lymphoma. The patients had elevated IgG- and IgM-anticardiolipin antibodies (aCL) and also tested positive for lupus anticoagulants. Other aPL were measured, and we found high positive results for all tested antibodies in three patients. The production of aPL, however, occurred in the absence of thrombotic complications. No thromboembolic manifestations occurred during the follow-up period either. It could also be demonstrated that the degree to which the aCL titre was elevated resembles the elevation of the non-classical antiphospholipid antibodies, but not that of beta2-GP-1 or anti-annexin antibodies. Therefore, it can be postulated that these extremely high levels of IgM-aCL antibodies do not enhance the risk of thrombosis and may be completely different from aCL antibodies in an antiphospholipid syndrome patient population without malignancies. In particular, haematological and lymphoproliferative malignancies may indeed be associated with the generation of aPL, but do not necessarily enhance the thrombophilic risk in these patients.