Cortisol increases have been associated with decreases in circulating lymphocytes and the increased expression of HIV by mononuclear cells. Cortisol may also affect disease progression by encouraging a Th2 cytokine response pattern instead of a Th1 cytokine response pattern.
Stressors also result in changes in immune regulation due to autonomic nervous system reaction.
Stress has been associated with the reactivation of latent viruses, such as herpesviruses, which may also activate the immune system and upregulate HIV replication. It is difficult to control for confounding variables and long-term longitudinal studies need to be conducted.