Abstract
A large-molecular mycobactericidal fraction associated with cathepsin and acid phosphatase activities was separated from detergent-extracts of the lung and spleen granular fraction of tuberculous mice by gel-filtration on Sephadex G-150 column. The mycobactericidal activity was expressed only in the acidic environment below pH 6.0, and the activity was reduced when the amount of bacilli exposed to the fraction was increased. The latter observation appeared compatible with the finding that the mycobactericidal activity was removed from the fraction by absorbing with heat-killed tubercle bacilli. Heating of the fraction at 100 C and pH 5.6 for 10 min destroyed both enzymatic activities completely, but the mycobactericidal activity remained unaffected. Incubation of the fraction at 40 C and pH 4.1 liberated the mycobactericidal moiety as a smaller-molecular protein separated from acid phosphatase activity. These findings and others suggested that the mycobactericidal principle existed in the form of a complex with lysosomal hydrolases, but as a factor distinct from them.
