The presence of systemic and local activated macrophages in mice infected in the foot pad with Mycobacterium leprae and M. marinum.

A highly sensitive assay for quantitating the presence of activated macrophages was employed to show that foot pad infection of mice with neither M. leprae nor M. marinum induced a population of activated peritoneal macrophages. In vitro attempts to demonstrate local activated macrophages in the foot pads of M. leprae infected mice failed, but, because of the technical problems encountered, do not preclude their presence. Additional studies are being carried out.