Analysis of T cell subsets by monoclonal antibodies in patients with tuberculosis after in vitro stimulation with purified protein derivative of tuberculin.

By using OKT monoclonal antibodies; OKT3(pan T), OKT4(inducer/helper), OKT8 (suppressor/cytotoxic) and OKIa1, T lymphocyte subsets were examined in lymphocytes of patients with tuberculosis both before and after in vitro stimulation with purified protein derivative of tuberculin (PPD). In freshly obtained lymphocytes samples before culture, a significantly high T4/T8 ratio in pleural fluid lymphocytes (PFL) from patients with tuberculous pleurisy was observed as compared with either their PBL, or the PBL from healthy controls. In addition, PFL from patients with tuberculous pleurisy showed increased numbers of E rosetting (E-RFC), OKT3+ and OKT4+ cells as compared with their PBL. A low T4/T8 ratio was also observed in PBL of patients with advanced, refractory tuberculosis. After stimulation with PPD in vitro, the T4/T8 ratio increased further in PFL as well as in PBL from patients with newly diagnosed, fresh tuberculosis. Investigation of fractionated T lymphocyte subsets revealed that PPD-induced proliferating lymphocytes belonged to T4+ and not T8+ lymphocytes. Ia antigen bearing T lymphocytes (Ia-T) were increased in all lymphocyte groups studied after in vitro stimulation with PPD. In particular, a remarkable increase was observed when PFL were stimulated in vitro with PPD. Our results suggest that the clinical features of tuberculosis reflect the immunological activity of T lymphocyte subsets in this disease.