Neuropsychological correlates of serum lymphocytotoxic antibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by frequent neuropsychiatric (NP) manifestations. At least two different pathogenetic mechanisms have been proposed for NP-SLE, including vasculitis and antibodies against neuronal antigens, the latter as expressed by the presence of brain cross-reactive lymphocyte antibodies. We have previously reported a high prevalence of cognitive dysfunction in SLE which can remain subclinical and which cannot be accounted for on the basis of disease activity, general distress, or steroid medication. In the present study, we undertook the same extensive, standardized neuropsychological testing in 98 consecutive female SLE patients in order to evaluate central nervous system functioning in relation to serum lymphocyte antibodies which were measured at the time of neuropsychological testing by a microcytotoxicity test. A significant association was observed between the presence of serum lymphocytotoxic antibodies (LCA) and cognitive impairment in patients with SLE. The pattern of impairment which predominated in the LCA-positive patients involved deficits in anteriorly associated, primarily visuospatial functions. These findings support the hypothesis of localization of a particular antigen-antibody interaction in the brain in SLE, suggesting the existence of immunological control mechanisms for normal brain functioning.