IL6 and major depressive disorder: Interestingly, clinical depression has, in a subset of patients, been reported to be accompanied by changes in immune responses, including a rise in the number of circulating leukocytes, lymphopenia [30,31,32], altered lymphocyte responses to mitogens [32,33,34,35], decreased neutrophil phagocytosis, but augmented monocyte phagocytosis [35,36] and increased circulating concentrations of IL-6 and the acute phase protein CRP [37,38,39].