Erythrocyte receptor (CD2)-bearing T lymphocytes are affected by diet in experimental pulmonary tuberculosis

Abstract

Outbred (Hartley) and inbred (strain 2 and 13) guinea pigs were vaccinated with Mycobacterium bovis BCG and placed on isocaloric, purified diets containing either 10 or 30% ovalbumin or on commercial guinea pig chow. Six weeks later, the animals were challenged by the respiratory route with virulent M. tuberculosis H37Rv. At intervals postchallenge, groups were tuberculin tested and sacrificed. Thymus-dependent (T) lymphocytes were enumerated either by rosette formation with rabbit erythrocytes or by the indirect immunofluorescence assay (IFA) with a guinea pig pan-T-cell monoclonal antibody, 8BE6. Protein-deficient guinea pigs of all three strains had significantly fewer erythrocyte rosette-forming (CD2+) T cells in the peripheral blood, and malnourished strain 2 and Hartley guinea pigs exhibited reduced levels of CD2+ T cells in the thymus. In contrast, animals of all three strains fed the low-protein diet harbored more CD2+ T cells in the bronchotracheal lymph nodes than did their control-fed counterparts. A larger proportion of lymphocytes from the blood and lymph nodes of all three strains were IFA positive than formed erythrocyte rosettes regardless of diet treatment. Diet had no effect on IFA-positive lymphocytes in those organs. Protein deficiency is associated with significant alterations in the number and/or distribution of T lymphocytes expressing functional CD2-receptors in BCG-vaccinated animals exposed to virulent mycobacteria by the pulmonary route. These alterations may contribute to the reduction in BCG vaccine efficacy observed in this model.