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 d ay for 14 days, with subsequent assessment of (a) thymic involution, (b) in vitro migration of stressed mice bone marrow cells toward thymocyte cultur e supernatants from neonates and from control or stressed mice, (c) composi tion of the bone marrow cell population, and (d) in vitro migration of norm al bone marrow cells toward stressed mice thymocyte culture supernatants. T he results obtained support the view that the reduced repopulation of thymu s by precursor T cells contributes to thymus involution associated with str ess. 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.