Can cryoglobulins interfere with the measurement of IgM antiphosphatidylethanolamine antibodies by ELISA?

Clinical manifestations of the antiphospholipid antibody syndrome (APS) have been recently related to the presence of phosphatidylethanolamine antibodies (aPE). However, it is well known that some molecules such as cryoglobulins, immunoglobulins that undergo a reversible precipitation at low temperatures, may interfere with biological assays. With this in view, we report the case of a patient with APS who was positive for both IgM aPE and type III cryoglobulinemia. Moreover, we show for this patient a potential implication of aPE in the cryoprecipitate formation. To further analyze the potential association between cryoglobulins and aPE, and also the possible consequences for aPE assay, we selected 55 patients according to positivity for both IgM aPE and cryoglobulinemia. Determination of IgM aPE levels was made before and after removal of cryoprecipitate from the serum. Of the 55 selected patients, 52 (95%) presented no significant difference for IgM aPE levels before and after cryoprecipitation. These results were ascertained whatever the aPE levels and clinical status of the patient. Taken together, our results indicate that cryoprecipitation does not interfere in most cases (95%) with the dosage of IgM aPE. Thus, IgM aPE do not appear to be involved in the formation of the cryoprecipitate.