Cytokine-Associated Emotional and Cognitive Disturbances in Humans. One element of the immune response is the secretion of infection-fighting circulating substances by lymphocytes (a class of white blood cells) activated by the presence of the infection. Many of us who look at the interface between behavioral disturbances and bodily physiology have suspected that these cytokines have direct — and deleterious — CNS effects and may account for some of the behavioral disturbance accompanying various physical illnesses. Here’s empirical evidence. Archives of General Psychiatry