| Abstract: | We have examined the effects of protein deprivation on the induction of oral tolerance for systemic antibody and DTH responses to the protein antigen ovalbumin (OVA). Mice were fed 4% or 24% protein diets from weaning and given a single feed of OVA 2 weeks later (short-term deprivation) or after 10 weeks (long-term deprivation). Tolerance for serum antibody responses was more profound in protein-deprived animals than in 24% protein-fed control groups. Conversely, tolerance for DTH responses was impaired in protein-deprived mice. This was demonstrated both for short-term deprivation, where nutritional rehabilitation after OVA feeding was necessary to demonstrate this effect on DTH, and for long-term deprivation. Furthermore, the effect of short-term deprivation on tolerance for DTH responses was similar to that observed after cyclophosphamide pretreatment of OVA-fed mice. Protein deprivation has disparate effects on the humoral and cell-mediated limbs of oral tolerance, and our results support the hypothesis that this regime selectively depletes a population of suppressor T cells responsible for the fine control of DTH tolerance. |
