Depression of Cell-Mediated Immunity during Acute Infectious Mononucleosis

Abstract

To elucidate mechanisms responsible for depression of cell-mediated immunity associated with viral infections, we studied 41 patients with infectious mononucleosis. Intradermal tests, lymphocyte stimulation in vitro and enumeration of peripheral blood T and B cells were performed. There was significant anergy and diminished lymphocyte responsiveness in vitro to mitogens and antigens during the first weeks of illness. This depression of cell-mediated immunity was accompanied by increased numbers of peripheral blood T and B cells. The numbers of atypical lymphocytes in the peripheral blood of several patients were too great to be classified as entirely T or B cells in type, and probably represent both types of lymphocytes. On the basis of these data, we hypothesize that T-cell response to viral infections results in antigenic competition, which is the major mechanism responsible for depression of cell-mediated immunity during infectious mononucleosis. (N Engl J Med 291:1149–1153, 1974)