The effects of thymus supernatant on the thymus homing ability of aged murine bone marrow cells

Effects of thymus supernatants on the phenotype of different subsets of peritoneum antigen-presenting cells

Peritoneal cells (PC) obtained 2 h subsequent to intraperitoneal (i.p.) injection of low doses (200 micrograms) of a purified fraction of rat male accessory glands (FI-RAG) are phenotypically and functionally different from those obtained 24 h after i.p. injection. In fast, PC obtained 2 h after FI-RAG injection are mainly IE+ and are involved in inducing specific suppression to RAG. In contrast, PC obtained 24 h after FI-RAG injection are mainly IA+ and capable of inducing specific response to RAG. For their induction, IA+ PC require cells within or recently derived from bone marrow. In order to analyze the mechanisms involved in IA+ bone marrow-dependent cell generation in the peritoneum, we studied the distribution of FI-RAG following i.p. injection. It was established that FI-RAG is found mainly in the thymus 2 h after injection and remains there for at least 24 h. Subsequently, we analyzed, in 4 groups of rats, the influence of thymic culture supernatants on the phenotype of cells appearing in the peritoneal cavity 2 h after FI-RAG injection. An increase in IA+ PC was observed 2 h after i.p. injection of FI-RAG in animals that had received either supernatants from normal thymic cells cultured with FI-RAG or those from thymic cells taken from animals injected with FI-RAG 2 h prior to being killed. Supernatants of thymic cells from animals injected with FI-RAG 24 h prior to being killed or from normal thymic cells do not increase the percentage of IA+ PC.(ABSTRACT TRUNCATED AT 250 WORDS)

The migration of bone marrow cells to thymic culture supernatants is inhibited by stress

The effect of immobilization stress on precursor cell migration from bone marrow to the thymus was studied in C57BL/6 mice. The in vitro migration assays, using Nucleopore chambers, showed that precursor cell migration to thymus supernatants was strongly inhibited in stressed animals. This inhibition of migration seemed to be cell-associated what can explain the thymic involution observed in mice under stress conditions. The migration of precursor cells from bone marrow may be one of the mechanisms by which the thymus gland is involuted by stress.