Lymphocyte subpopulations and reactivity during and after infectious mononucleosis.

T- and B-lymphocyte numbers, as well as lymphocyte reactivity to mitogens in vitro, were studied and correlated to other laboratory tests during the acute phase of infectious mononucleosis (30 patients) and up to one year thereafter. During the acute disease an absolute increase in both T- and B-lymphocyte numbers was recorded, the relative increase in B-lymphocytes occurring at the start. B-lymphocyte numbers fell after the second week and T-lymphocyte numbers after the fourth week of disease. Lymphocyte activation was impaired in all patients during the acute phase and was still significantly impaired for some mitogens after 6-9 months. Very few correlates between lymphocyte tests and other laboratory and clinical parameters were found.