Vaccination with Mycobacterium bovis BCG affects the distribution of Fc receptor-bearing T lymphocytes in experimental pulmonary tuberculosis

Abstract

Inbred strain 2 guinea pigs were vaccinated with Mycobacterium bovis BCG or were left unvaccinated and challenged 6 weeks later by the respiratory route with virulent Mycobacterium tuberculosis. By using a double rosette assay with isotype-specific antibody-coated ox and uncoated rabbit erythrocytes, the proportions of T lymphocytes bearing Fc receptors for immunoglobulin G (IgG) (T gamma cells) or IgM (T mu cells) were quantified in tissues taken from animals that were killed within 4 weeks postchallenge. Tuberculin reactivity in vivo and in vitro and antimycobacterial resistance were also measured. BCG vaccination protected the guinea pigs and resulted in significantly enhanced proportions of T mu cells in the blood during the first 3 weeks and in the spleen during weeks 2 and 3 postchallenge. Levels of T gamma cells declined in all tissues during the first 3 weeks of infection and were unaffected by prior vaccination with BCG. Increased proportions of T mu cells in the blood were accompanied by dramatic tuberculin skin reactions and purified protein derivative-induced lymphoproliferation in BCG-vaccinated guinea pigs during the first 2 weeks following virulent pulmonary challenge. Peak levels of T mu cells in the spleens of vaccinated animals at 2 weeks coincided with the first appearance of virulent mycobacteria in that organ. BCG vaccination appears to influence immunoregulatory events in pulmonary tuberculosis through effects on the distribution of IgM Fc receptor-bearing (T mu cell) T lymphocytes.

Protein malnutrition alters the distribution of Fc gamma R+ (T gamma) and Fc mu R+ (T mu) T lymphocytes in experimental pulmonary tuberculosis

“…Evidence for a helper-inducer role for these cells comes from early studies demonstrating that T,u cells drive B-cell differentiation in the presence of pokeweed mitogen (14). We recently observed significant increases in T,u levels in the blood and spleens of BCG-vaccinated guinea pigs responding successfully to virulent pulmonary infection (1). When this fact and the results presented here are considered, it appears likely that the T,u subset promotes appropriate T-cell function.…”

“…A blood sample was immediately obtained via cardiac puncture. The spleen and bronchotracheal lymph nodes were removed aseptically, and a single-cell suspension was prepared (1). Blood lymphocytes were obtained by density gradient centrifugation (3).…”