The effect of cortisone on the multiplication of M. tuberculosis in normal and immune mice

The multiplication of M. tuberculosis, var. bovis inoculated into the cornea of mice was studied by staining the whole cornea at various stages after inoculation. Four groups of animals were studied: untreated animals, animals treated with cortisone, animals previously immunized with the same bovine strain, and immunized animals treated with cortisone.In the untreated immunized group little or no multiplication occurred. In the other three groups multiplication did occur and was about the same for the first week after inoculation. After this stage, cortisone-treated animals, whether previously immunized or not, showed increased multiplication and massive cord formation, as compared with untreated animals in which little further multiplication was seen. The cortisone treatment had thus completely suppressed immunity. The significance of these results is discussed.