Rat thymic dendritic cells: cell surface marker variations in culture

Rat thymic dendritic cells (DC) have been analyzed by flow cytometry in order to study the variations on the cell surface marker expression upon culture at 37 degrees C. Our results demonstrate that whereas expression of major histocompatibility complex (MHC) molecules, CD45, Mac-1, LFA-1, B-cell markers, macrophage markers and some T-cell markers (as CD2, CD4 and CD8) did not undergo changes in culture, the level of expression of the adhesion molecules VLA-4 and ICAM-1, and the T-cell markers CD5, CD25 and Thy-1 increased after 14 h incubation at 37 degrees C. VLA-4, ICAM-1 and Thy-1 expression was up-regulated from intermediate to high levels, the percentage of CD5+ cells increased from 20% to 50%, and the interleukin-2 (IL-2) receptor alpha chain (CD25) was induced in 50% of DC after the culture period. These results are discussed with regard to the functional significance of DC phenotypic variations, and their implications concerning the development of in vitro systems designed for T-cell differentiation studies involving purified DC.