In vitro bone marrow cell migration to supernatants prepared from thymic epithelial cell cultures.

Thymic epithelial cell cultures were established from neonatal CBA/J mice by inhibition of fibroblast overgrowth. Epithelial cells were identified by their cobblestone appearance in culture, by the presence of keratin, and by ultrastructural analysis demonstrating desmosomes. Supernatants were prepared by incubation of confluent cultures of these cells in serum-free media. Using blind well chambers, these supernatants were chemoattractive to murine bone marrow cells, enriched for immature lymphoid cells, and decreased the myeloid to lymphoid ratio in the migrating cell population. Interleukin 2 had no effect as a modulator of this chemoattraction, nor did it possess chemoattractive properties. Supernatants prepared from epidermal growth factor stimulated thymic epithelial cells possessed significantly enhanced chemoattractive properties to bone marrow cells, and was found to be a thymic epithelial cell mitogen. Supernatants from serum-free cultures of thymocytes also induced a significant migration of bone marrow cells but were found to enrich for mature myeloid cells.