Loss of class I MHC function alters behavior and stress reactivity

The importance of the classical immune molecule, class I major histocompatibility complex to central nervous system function is one of the most surprising discoveries related to neuroimmunology in the past decade. Mice lacking both β-2microglobulin and transporter associated with antigen processing (β2M-/-TAP-/-) showed differences in basal behavior. In response to saline injection, β2M-/-TAP-/- mice showed a significant hypothalamic pituitary adrenal activation that was not observed in wild type mice, while lipopolysaccharide-induced cytokine expression in the hypothalamus was similar in β2M-/-TAP-/- and wild type mice. Overall, these data show that class I MHC plays an important role in behavior and stress reactivity.