Production of migration inhibitory factor in inbred rats

Strains of genetically inbred rats representative of the known Ag-B groups produced migration inhibitory factor in response to immunization with live bacillus Calmette-Guerin bacilli and intracardiac challenge with old tuberculin; the assays were performed by both in vitro and in vivo methods. None of the strains immunized in this fashion developed delayed hypersensitivity skin reactions to purified protein derivative.