Sensitization to lepromin in presumably non-leprous individuals

RESUMO

The experiments which have been reported demonstrate that 1- It is possible to sensitize presumably non-leprous persons to leprominby intradermal injection of either an oily or an aqueous suspension of Mycobacterium leprae killed by hat. Furthermore, this sensitization ensues in a high percentage of subjects. 2- Sensitization to lepromin can be produced also by intradermal injection of suspensions of Mycobacterium tuberculosis killed by heat. This is in agreement with the opinion which we have expressed (10,11) in discussing positive lepromin reactions in patients with cutaneous tuberculosis and in persons who had been vaccinated with B.C.G. 3- The early lepromin reaction is attributable to previous intradermal injection of purified lepromin protein (L.P.P.), nor by injection of a suspension of E. typhosus killed by heat. 5- As regards the duration of sensitivity to lepromin, a final answer cannot be given. We have observed positive early reactions to the antigen L.P.P. in presumably non-leprous individuals who have received endermal injections of integral lepromin five years previously. 6- As to the practical value of allergic response as an element of protection against later infection, we believe that it is more desirable for an individual exposed to leprosy to have a positive lepromin reaction. Unfortunately it is not possible to provoke this supposedly protective allergy, since apparently it is dependent on an unknown factor which may be constitutional. When that factor is lacking, nothing can be gained by the intradermal injection of the antigen. However, if the factor is present in an individual as evidency by his capacity to reactin an allergic manner to the antigen, we believe that he will always have a high degree of immunity to leprosy, regardless of his previous state os sensitization.