Lack of Mycobacterium leprae-specific uptake in Schwann cells

Among mycobacteria, Mycobacterium leprae have a unique property to infect peripheral nerves, which is the cause of a variety of debilities seen in leprosy. The possibility of selective uptake of M. leprae by Schwann cells was studied using a rat Schwannoma cell line 33B and rat sciatic nerve-derived Schwann cells. M. leprae were phagocytosed by 33B cells but so also were seven other mycobacteria ('Mycobacterium w,' BCG, M. tuberculosis H37Rv, M. non-chromogenicum, M. vaccae, ICRC bacillus, and M. smegmatis) which do not involve peripheral nerves. All three mycobacteria tested (M. leprae, M. tuberculosis and 'Mycobacterium w') were phagocytosed by sciatic nerve-derived Schwann cells. Both Schwannoma and Schwann cells phagocytosed even inert latex particles. These results fail to demonstrate any M. leprae-specific uptake system in Schwann cells.