Abstract
The passive transfer of rabbit anti-mycobacterial immunoglobulins was directed against either living or soluble extracts of Mycobacterium tuberculosis strain H37Rv, which promotes the multiplication of the BCG strain of M. tuberculosis in the spleen of mice infected with low doses of this latter strain. This enhancing effect was reduced significantly when antisera were absorbed with living BCG. Moreover, such treatment led to the removal of all hemagglutinating antibodies when antisera were tested against either BCG or H37Rv soluble extracts. Therefore, it is most probable that the enhancing effect is related to the presence of mycobacterial antibodies.