MOUSE THYMUS DENDRITIC CELLS - KINETICS OF DEVELOPMENT AND CHANGES INSURFACE-MARKERS DURING MATURATION

The early thymus precursor population of adult mice has the capacity t o generate T cells, B cells and dendritic cells (DC). These precursors were injected into the thymus of irradiated recipients in order to fo llow the kinetics of thymic DC development. The resultant cohort of T- lineage cells developing in the thymus was accompanied by a parallel c ohort of DC, present at 10(3)-fold lower frequency. The intrathymic li fespan of these DC was as short as that of T-lineage thymocytes. As th e thymic DC matured, some markers characteristic of the original precu rsor population gradually declined (Ly-5, c-kit, Sca-2) whereas marker s characteristic of thymic DC appeared and were maintained (major hist ocompatibility complex class II, CD11c, NLDC-145 and CD8 alpha). Some thymic DC expressed the early B-cell marker BP-1, and BP-1 mRNA, throu ghout their maturation. The surface markers on thymic DC could be divi ded into two groups. Some markers, including class I and class II MHC, CD8 alpha and BP-1, appeared to be integral components of the DC surf ace. In contrast, other markers, including Thy-1, CD4 and CD8 beta, ha d probably been picked up from associated thymocytes.