MONOCLONAL ANTIPHOSPHATIDYLSERINE ANTIBODIES REACT DIRECTLY WITH FELINE AND MURINE CENTRAL-NERVOUS-SYSTEM

Objective. Antiphospholipid antibodies (aPL), especially against phosp hatidylserine and cardiolipin, are associated with a variety of neurol ogical disorders. While it is believed aPL react with endothelial cell s to cause cerebral thrombosis, it is not known to what degree aPL rea ct with neural tissue nor which particular aPL specificities may be mo re relevant. We investigated direct aPL reactivity with the central ne rvous system (CNS) using 3 monoclonal IgM aPL that differentiate betwe en cardiolipin and phosphatidylserine dependent antigens. Methods. Bra in and spinal cord from normal cat Felis domesticus and brain from CD- 1 mice were reacted with aPL using indirect immunoperoxidase technique s. Monoclonal aPL were reacted with whole brain myelin by dot immunobl ots. Results. Monoclonal D11A4, reactive with cardiolipin and not phos phatidylserine (CL+/PS-), did not react with any portion of the tissue . Both monoclonal 3SB9b (CL-/PS+) and BA3B5C4 (CL+/PS+) reacted in fel ine and murine CNS. Both labeled myelinated fibers in grey and white m atter of brain and spinal cord in an identical pattern with positive c ontrol antibody against myelin basic protein and reacted with whole hu man brain myelin by dot immunoblot. 3SB9b (CL-/PS+) additionally react ed with ependyma and epithelium of the choroid plexus. Conclusion. aPL , especially those reactive with phosphatidylserine dependent antigens , react directly with epitopes associated with myelin, brain ependyma, or choroid epithelium. Direct reactivity of aPL with nervous tissue m ay be relevant to neurological disorders.