Pro-inflammatory cytokine levels are raised in female schizophrenia patients treated with clozapine

Abstract Background We have previously shown that the neurotrophic factor, S100B, is raised in serum samples of female patients with schizophrenia, but not male patients, compared to controls, and this may be associated with raised BMI. Here we analysed the levels of additional proinflammatory cytokines in patients with schizophrenia to further investigate these gender differences. Methods The levels of six cytokines (IL1β, IL6, IL8, IL17, IL23, TNFα) were measured in serum samples obtained from patients with schizophrenia, treated with clozapine (n = 91) and compared with healthy controls (n = 50). Individual cytokine levels were measured using dot-immunoblotting methods and a ‘cytokine signature’ was also generated by summing all 6 cytokines. Treatment time, patient age, gender, illness severity and metabolic parameters were also measured. Results The levels of proinflammatory cytokines and BMI were significantly raised in female, but not male, patients treated with clozapine compared to healthy controls. Compared to individual cytokines, the ‘cytokine signature’ analysis showed less scatter of data although this ‘cytokine signature’ method did not improve separation of individual patients and controls. Conclusions This study supports previous findings that raised BMI, which is likely associated with increased number of adipocytes, may contribute to increased cytokine serum concentrations in females.