Studies on thymocyte subpopulations in guinea pigs. X. Rosette-forming ability of thymocyte subpopulations before and after incubation in vitro.
Thymocytes spontaneously proliferating in vitro were labelled with 3H-thymidine, and the distribution of label among rosette-forming cells (RFC+) and nonrosetting cells (RFC-), as well as in populations differing in buoyant density, was measured by liquid scintillation counting and autoradiography before and after incubation for 24 h. Initially most labelled cells (88%) belonged to the low-density (1a) subpopulation, the majority being RFC+. After incubation for 24 h, low-density nonrosetting thymocytes (1a, RFC-) contained the highest amount of label. A decreased rosette formation occurred not only in labelled cells but also in the population as a whole, and in separately incubated high-density cells. The decreased rosette formation was mainly caused by a change in rosette-forming ability of viable high-density cells, however in part also by decreased viability. A shift from low to high density occurred among labelled cells during incubation and was shown to occur in both RFC+ and RFC-. The decreased rosette formation of labelled cells during in vitro culture contrasts with the increase earlier observed in vivo and may therefore represent affinity alterations or a down-regulation of the rosette receptor in vitro. We conclude that the observed changes in density, but not in rosette-forming ability, may reflect normal differentiation.
Kölare
S
S
Department of Histology and Neurobiology, Karolinska Institute, Stockholm, Sweden.
Sandberg
G
G
D000818:Animals; D002450:Cell Communication / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002469:Cell Separation; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D006224:Cricetinae; D008297:Male; D012397:Rosette Formation; D013950:Thymus Gland / Q000166:cytology* / Q000502:physiology