The Proportion of CD45RA+CD62L+ (Quiescent-Phenotype) T Cells within the CD8+ Subset Increases in Advanced Weight Loss in the Protein- or Energy-Deficient Weanling Mouse

Abstract

Male and female C57BL/6J mice, initially 19 d old, had free access to a complete purified diet, were fed this diet in restricted daily quantities, or had free access to a low-protein diet. Three separate studies were conducted with feeding periods of 14, 9 or 6 d (n = 7-8 per dietary group and feeding period; 6 d: restricted intake and age-matched controls only). A zero-time control group (19 d old) was included in each study. Malnourished mice lost approximately 2% of initial body weight daily. Naïve-phenotype (quiescent) CD8(+) T cells of the blood, spleen and mesenteric lymph nodes were identified on the basis of surface coexpression of CD45RA and CD62L. Relative to age-matched controls, the percentage of naïve-phenotype CD8(+) T cells was high in energy-restricted groups after 9 d and 14 d of weight loss and in the protein-restricted groups after 14 d (P < or = 0.05). No ontogenetic change was apparent (age-matched vs. zero-time control). Other studies have demonstrated depression in cell-mediated immune competence in both malnutrition models within the first week of weight loss. An overabundance of quiescent-phenotype T cells within the involuted CD8(+) compartment may contribute to established immune depression but not to its initiation in weight loss pathologies.