Role of pre-T cells and chemoattractants on stress-associated thymus involution.

Male C57BL/6 mice were stressed by immobilization for 1, 2, 3, or 5 h per day for 14 days, with subsequent assessment of (a) thymic involution, (b) in vitro migration of stressed mice bone marrow cells toward thymocyte culture supernatants from neonates and from control or stressed mice, (c) composition of the bone marrow cell population, and (d) in vitro migration of normal bone marrow cells toward stressed mice thymocyte culture supernatants. The results obtained support the view that the reduced repopulation of thymus by precursor T cells contributes to thymus involution associated with stress. It is further shown that this effect could be owing to a reduction in the number of precursor T cells in the bone marrow, and/or to a diminished production of precursor T-cell chemoattractants.