ICRC vaccine-induced changes in M. leprae-specific cell-mediated immunity in langur (Presbytis entellus) monkeys.

The effects of the administration of ICRC antileprosy vaccine on skin reactions and lymphocyte transformation tests (LTT) to antigens of Mycobacterium leprae have been investigated in Hanuman langur monkeys (Presbytis entellus) which live native to north India. In a majority of these monkeys, the vaccine brings about lepromin conversion associated with a change in tissue response consistent with "ugrading" of immunity. However, no concomitant changes were observed in the LTT. The significance of these observations is discussed. It is proposed that the langur monkey could be used as a laboratory model to screen "candidate" antileprosy vaccines.