Studies of platelet monoamine oxidase activity in Epstein-Barr and dengue virus infections.

As part of a prospective, psychosocial, and biochemical study of infectious mononucleosis, platelet monoamine oxidase (MAO) activity has been evaluated as a host factor. It was found that platelet MAO activity may be a possible predisposing host factor but not a precipitating factor. The results on infectious mononucleosis, a viral disease which involves the host's cell-mediated immune system, are compared with an evaluation of platelet MAO activity in dengue, a viral disorder involving the host's humoral immune system. The platelet MAO activity in these disorders has been compared to that in schizophrenia, a disease for which low platelet MAO activity has been postulated, from retrospective and twin studies, to be a risk factor. One hypothesis suggests that low platelet MAO activity predisposes to development of schizophrenia, but also increases cell-mediated immune system responses.