Vaccine failure in malnourished animals: use of a bioimmunomodulator to improve immunocompetence.

Vaccine failure attributable to immunodeficiency is common in stressed individuals. During vitamin-B complex and ascorbic acid malnutrition in experimental animals, vaccine failure is accounted for by the atrophy of the immunocompetent organs. In an attempt to improve immunocompetence, a bioimmunomodulator obtained from the supernatant fluid from cultured normal bone-marrow cells was injected following immunization into young animals receiving a diet deficient in vitamins B and C. This treatment improved the immunosurveillence of mice and rats approximately 3 to 4 fold. Peculiarly, this factor failed to evoke immunostimulation in normal immunized animals, probably because of a suppressing mechanism.