A chemotactic factor for rat thymocytes may regulate T-lymphocyte migration toward the thymic microenvironment.
Using a modified Boyden chamber assay, extracts or culture supernatants of rat thymic stromal cells, or thymocytes were examined by chemotactic activity to rat leukocytes. Rat thymocytes responded chemotactically to the aqueous extract as well as to culture supernatants of thymic stromal cells. However, neither the extract and culture medium from concanavalin A-stimulated thymocytes nor any component of rat serum has shown such an activity. The thymic extract was fractionated into three molecular species with chemotactic activity for thymocytes. The thymocyte chemotactic factor(s) (TCFs) in the extract was distinct from known lymphocytic chemotactic factors, such as interleukin-1 (IL-1), IL-2, C5a, and the culture supernatant of stimulated thymocytes. In vitro, TCFs could attract, in addition to thymocytes, bone marrow cells, fetal liver cells, and nylon-wool nonadherent lymphocytes from peripheral blood and spleen. Lymph node cells, neutrophils, macrophages, and B cells from peripheral blood could not respond to TCFs. Thymocytes also responded to the extract of splenic stromal cells. Unlike the thymic extract, however, the splenic extract was chemotactically active for lymphocytes from lymph nodes but not for bone marrow cells. These results indicate that thymic stromal cells secrete a chemotactic factor(s) for a relatively immature type of T-lineage cells, which may by a thymus-homing progenitor T cell, while spleen may contain an attractant for a relatively mature type of T-lineage cells.
D000818:Animals; D002630:Chemotactic Factors / Q000302:isolation & purification* / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D002850:Chromatography, Gel; D003470:Culture Media / Q000032:analysis; D005260:Female; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000502:physiology; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D009928:Organ Specificity; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D013950:Thymus Gland / Q000032:analysis*
D002630:Chemotactic Factors; D003470:Culture Media