Immune responses of the protein-deficient guinea pig to BCG vaccination

Two groups of guinea pigs were maintained on high-protein and low-protein diets and immunized with intradermal BCG. Protein deficiency was accompanied by marked inhibition of local and systemic immune responses: a) The BCG nodule was poorly formed. There was marked delay and deficiency in the mobilization of macrophages. b) The draining lymph node was atrophic and showed little or no proliferation of lymphoid cells in the paracortical area. Macrophage accumulation occurred late but became diffuse and marked, in contrast to its consistent scarcity in the BCG nodule. c) In either location epithelioid cell transformation was retarded. Well-formed mature epithelioid cell granulomas were not seen. d) Bacilli persisted for a long time in the skin and lymph node lesions, e) Tuberculin sensitivity was greatly impaired in one-fifth of animals and absent in others. These findings were suggestive of macrophage dysfunction and depression of cell-mediated immunity to BCG in the protein-deficient guinea pig.