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Conditioning of Nude bone marrow increases in vitro migration to thymus supernatant.

The thymus must be continuously seeded by cells termed prothymocytes in order to maintain normal T-cell development (Scollay et al. 1986). Using parabiotic studies, the source of prothymocytes appears to be either from the fetal liver or the adult bone marrow (Roderwald et al. 1992). The ability of the body to distinguish self from non-self and mount a functionally mature immune response is dependent upon the intrathymic education of these cells. Therefore, it is apparent that successful migration of prothymocytes into the thymus is an inescapable event in the development and maintenance of the immune system. Utilization of the athymic Nude mouse is a valuable asset in the elucidation of the mechanisms influencing the migration of bone marrow cells into the thymus. Its aberration enables investigators to examine the effect of thymic factors on cells previously devoid of thymic influence. In an attempt to understand the migration of normal prothymocytes into the thymus, we analyzed the in vitro migration of athymic bone marrow cells towards newborn thymus supernatant. Adult athymic murine bone marrow cells were incubated in either thymus supernatant or media and allowed to migrate toward one or the other. Similar control experiments were performed using CBA adult mice. Results indicate that athymic bone marrow migration towards both supernatant and media can be restored to control levels after incubation in thymus supernatant.