T cells with a quiescent phenotype (CD45RA(+)) are overabundant in the blood and involuted lymphoid tissues in wasting protein and energy deficiencies

The objective of this investigation was to determine the influence of disti nct forms of acute weight loss on the expression of the quiescence marker, CD45RA, by T cells in several lymphoid compartments including the blood. Ma le and female weanling mice, CBA/J and C57BL/6J strains, were allocated to the following groups: acl libitum intake of a complete purified diet: restr icted intake of the complete diet; and ad libitum intake of an isocaloric l ow-protein diet. The restricted intake protocol produced weight loss throug h energy deficiency (marasmic-type malnutrition), whereas the low-protein d iet caused wasting through inadequate protein nitrogen and induced a condit ion mimicking incipient kwashiorkor. In one experiment, weanling mice of bo th strains were maintained for 14 days according to each of these dietary p rotocols and, in a supplementary study, C57BL/6J weanlings consumed either the complete diet or the low-protein diet Lrtl lihiirllil for 21 days. Zero -time control groups (19-days old and 23-days old in C57BL/6J and CBA/J str ains, respectively) were included in the first experiment to control for on togeny-related change. Expression of CD45RA was assessed by two-colour flow cytometry in CD4(+) and CD8(+) T cells from the spleen, mesenteric lymph n odes and blood. Within 14 days, energy-restricted mice exhibited a high per centage of CD4(+) T cells expressing CD45RA in all three lymphoid compartme nts in both mouse strains (an average of 50% CD45RA(+) versus 9% in well-no urished controls), and a similar outcome was apparent in the CD8(+) subset (93%;, CD45RA(+) versus 63%). Mice fed the low-protein diet required up to 21 days to exhibit the same imbalance within the CD4(+) T-cell subset (33% CD45RA(+) versus 4% in well-nourished controls). A shift toward a quiescent phenotype occurs throughout the peripheral T-cell system in acute wasting disease. Consequently, the quiescence-activation phenotype of blood T cells reflects the same index in secondary lymphoid organs in such pathologies. Naive-type quiescence among T cells is implicated as a component of depress ed adaptive immunocompetence in the advanced stages of diverse forms of acu te weight loss.