Surface characteristics of thymocytes in glucocorticoid treated rats using rosette-formation technique and surface marker analysis.

Glucocorticoid (GC) treatment is known to induce destruction of cortical thymocytes and then their reconstitution. By using the rats treated with GC, we examined the relationship between rosette-formation and surface markers (CD4 and CD8) for clarifying the processes of differentiation and maturation in rat thymocytes. Thymus weight and thymocyte count began to decrease immediately after GC administration and became minimal on 5-7 days, followed gradual recovery. The percentage of rosette-forming thymocytes began to decrease immediately after GC treatment and became minimal on 5 days, followed by recovery to the normal level by the 10th to 14th day after treatment. During the analysis of the changes in the percentage of 4 subsets (CD4-8-, CD4+8+, CD4+8+, CD4-8+) of rat thymocytes after GC treatment, the percentage of CD4+8+ cells was found to change in close relation to the change in the percentage of rosette-forming lymphocytes, suggesting that rosette-forming thymocytes are CD4+8+ cells. These results suggest that the treatment induces destruction of GC-sensitive thymocytes, possibly rosette-forming cells, followed by migration of precursor T cells (CD4-8- cells) in the thymus, and that the precursors change into rosette-forming cells (CD4+8+ cells) in the thymus, followed by differentiation and maturation into non-rosette-forming cells (CD4+8- or CD4-8+ cells).