Cell membrane predictors of response to lithium prophylaxis of affective disorders.

HLA antigens and RBC/plasma lithium ratio were studied in a sample of 49 patients, diagnosed as bipolar affective psychotics (n = 22), unipolar depressive psychotics (n = 18) and cycloid psychotics (n = 9), receiving prophylactic lithium for 1-4 years and maintained at lithium plasma levels of 0.6-1.2 mEq/1. Mean values of the ratio were found to be significantly higher in patients who responded to treatment when compared with non-responders, whereas the frequency of the HLA-A3 antigen was significantly higher in non-responders. The only 6 patients with a lithium ratio above the median and the absence of the HLA-A3 antigen coexistent with bipolarity and a family history of the illness were all good responders to treatment. Further research in this field will probably bring about the isolation of a subgroup of lithium-responsive patient with well-defined clinical and biological features. When patients were divided into two subgroups according to their lithium ratios (above and below the median), the HLA-A3 and Aw26 antigens were found to be significantly more frequent in those with ratios below the median. It can be hypothesized tha these antigens disturb transport in some way, leading to low lithium ratio values.