T cell recruitment from the thymus to the spleen in tumor-bearing mice. I. Analysis of recruited cells by surface markers.

After inoculation of tumor cells (methylcholanthrene-induced sarcoma), the number of Thy 1+ cells and PNA (peanut agglutinin) binding cells, which were shown to be different subpopulations were increased in the spleen of thymus-intact mice, in contrast this increase was not observed in adult thymectomized mice. In experiments performed concurrently with splenic cell analysis, we found that the plasma PGE2 levels declined in parallel with the tumor growth. Prevention of such a decline of plasma PGE2 level by replenishment with exogenous PGE2 inhibited the splenic cell increase in tumor bearers. In the tumor-bearing mice, cell traffic systems from the thymus to the periphery was ascertained by injecting fluorescein diacetate (FDA) into the thymus and observing fluorescein positive cells in the periphery. We suggest that increased recruitment of thymic cells to the periphery may be mediated by PGE2 in the presence of a tumor.