PLATELETS FROM SCHIZOPHRENIC-PATIENTS BEAR AUTOIMMUNE ANTIBODIES THATINHIBIT DOPAMINE UPTAKE

Platelet-associated antibodies (PAA) from schizophrenic patients and h ealthy individuals were determined by conventional enzyme immunoassay. The platelets of the schizophrenic patients were found to carry notab ly higher levels of PAA than were those of the healthy controls. PAA f rom the schizophrenics inhibited specifically the uptake of dopamine ( DA) by platelets. The DA uptake by normal platelets could be reduced t o a level similar to that observed in platelets of schizophrenics upon binding of PAA from schizophrenics. Serotonin uptake was virtually un affected by these antibodies. The Vmax value of dopamine uptake by pla telets of schizophrenics was similar to that for normal platelets trea ted with FAA of schizophrenics, as well as that for normal untreated p latelets. However, the Km values of the uptake were higher in the plat elets from schizophrenics and normals treated with PAA from schizophre nics than in the untreated platelets of normals. PAA from schizophreni cs were found to bind to rat brain P2m membranes and to interfere with the binding of the dopamine receptor ligands [H-3]-dopamine and [H-3] -spiperone. These results suggest that blood platelets may function as a peripheral epitope for the formation of PAA, which, when reaching t he brain, may react with the dopamine receptor and elicit mental disor der.