B-cell immune response during total protein deprivation.

Female adult rats fed with a protein-free normocaloric diet were antigenically stimulated with 1.3 x 10(-9) sheep red blood cells. Lymphoid spleen population, spleen plaque forming cells and serum haemolysins were measured in experimental as well as in control animals fed with a normal (18% protein) diet. A persistent diminution, proportionally related to the period of protein deprivation, of all parameters studied was observed; the fall was more prominent for haemolysin titre which became undetectable after 15 days of protein-free diet. Also, animals exposed to the aproteic diet during 15 days were afterwards returned to a normal diet and maintained on it during variable periods of time. A rapid restoration of the humoral response capacity, up to 60% of normal after 4 days of protein intake, and completely normal, following 6 days of refeeding, was observed. These findings suggest that protein starvation influences the production of circulating antibodies more than the antibody-forming cells. The aproteic induced impairment involved in the immunoglobulin synthesis does not appear to be irreversible, at least during the dieting period explored in the present study.