The fate of leprosy bacilli in fibroblasts cultivated from macular and tuberculoid lesions.

A preceding communication (1) reported the maintenance of fibroblasts from lepromata in serum media for periods of 14 to 34 days. The heavily bacillated macrophages died in situ and deposited their bacilli within the original explants. A relatively low proportion of smaller round cells which sometimes migrated into the plasma, were not sustained by serum media, as had been hoped, and disappeared early in the history of the cultures. The fibroblasts which persisted throughout the history of the cultures contained relatively few bacilli. Quantitative rating of the bacillary content of the original explants failed ' to disclose any increase in the total mass of the bacilli during tissue cultivation, a result in agreement with earlier microscopic counts in lepromatous tissue fragments maintained under bacteriological conditions (2). Since any bacilli which might be growing in these cells could not be distinguished from those acquired by phagocytosis it was not possible at that time to settle the question of bacillary multiplication in the growing cells.