Illustration of some of the ways in which malnutrition and infection modulate immune response and central involvement of the hypothalamic pituitary axis, as described in the text. Abbreviations: APR, acute-phase response; IR, immune response; lymphs, lymphocytes; grans, granulocytes; pre T, B, early uncommitted T and B lymphocytes in bone marrow; Pro T, B early committed T and B lymphocytes in bone marrow; TLR, Toll-like receptor.