The Reaction to Lepromin of Patients with Sarcoid or Tuberculosis Compared with that of Patients in General Hospitals with a Discussion of the Mechanism of the Reaction 1
Summary 1. In patients with sarcoid, reactions to lepromin were infrequent and slight; no indication was found that sarcoid is atypical tuberculoid leprosy. 2. Slight (1 plus) lepromin reactions are of doubtful significance. 3. The incidence of intense or moderately intense lepromin reactions in a control group of persons in a non-endemic area of the United States is less than that in endemic areas of the tropics. 4. Strongly positive late lepromin reactions occurred in patients with active pulmonary tuberculosis. 5. The high incidence of intense or moderately intense lepromin reactions in persons with strongly positive tuberculin tests suggests the presence of common sensitizing antigens. 6. A possible mechanism based on soluble protein or polysaccharide antigens is suggested to explain the early lepromin reactions observed in persons with positive tuberculin reactions. 7. The possibility is suggested that the mechanism of the late lepromin reactions in persons with positive tuberculin tests, or with active pulmonary tuberculosis, may be related to insoluble, firmly bound lipid fractions which would be slowly liberated by destruction of Mycobacterium leprae in tissues. 8. By comparison with the cellular response to purified lipid fractions of Mycobacterium tuberculosis, the mononuclear response to lepromin observed at biopsy further suggests a lipid as the active chemical fraction. 9. If tuberculosis is ruled out by a suitable control substance, lepromin may prove useful in the diagnosis as well as the prognosis of leprosy. 10. No adequate control substance for interpretation of the late lepromin reaction has yet been introduced. 11. Leprosy may be, like tuberculosis, a disease of high contagion, slow progression, and high curability, requiring repeated regular exposures to the infecting organisms. 12. Attempts should be made to recover Mycobacterium leprae by inoculation of tissue cultures of monocytes or of chick egg chorio-allantoic membrane with infected material, since pathologic evidence suggests that the living monocyte furnishes a substance essential for growth of the organism. Attempts to reproduce the disease should also be made by frequent inoculations of living organisms into animals over a long period of time.