CLINICAL-EVALUATION OF MPT-64 AND MPT-59, 2 PROTEINS SECRETED FROM MYCOBACTERIUM-TUBERCULOSIS, FOR SKIN-TEST REAGENTS

Setting: Department of Pulmonary Medicine P, Bispebjerg Hospital, Cope nhagen, Denmark. Objective: To study the ability of two proteins secre ted from Mycobacterium tuberculosis, MPT-64 and MPT-59 to induce delay ed type hypersensitivity (DTH) reactions following intradermal adminis tration. Design: In a small scale clinical investigation, skin reactio ns to these antigens were compared to reactions to tuberculin PPD RT23 in 1) patients with active tuberculosis, 2) BCG vaccinated healthy su bjects with close contact with tuberculous patients, and 3) BCG vaccin ated healthy subjects without contact with tuberculous patients. Tests for in vitro reactivity to these antigens were carried out in similar groups. Results: All subjects gave positive reaction to tuberculin PP D RT23, whereas approximately half of the subjects in each of the thre e groups reacted to MPT-59. Two subjects (one patient with tuberculosi s and one healthy bacille Calmette-Guerin vaccinated subject without p atient contact) reacted to MPT-64. The studies of cell proliferation a nd induction of interferon-gamma (IFN-gamma) following stimulation wit h tuberculin PPD and MPT-64 supported this profile of reactivity. Conc lusion: None of the experimental skin test antigens had properties sup erior to tuberculin PPD RT23 in humans. The failure of MPT-64 to induc e delayed type hypersensitivity reactions in the majority of tuberculo sis patients is discussed, in view of the potent reactivity to MPT-64 in tuberculous guinea pigs.