M Konishi

Analysis of cell surface antigens on glucocorticoid-treated rat thymocytes with monoclonal antibodies

The effects of glucocorticoid (GC) on thymocytes have been utilized to investigate the maturation and differentiation of thymocytes, but these experiments have mainly been performed on mouse thymocytes. We investigated the cell surface antigens expressed by LEW rat thymocytes during thymic reconstitution after GC treatment. Three-color flow cytofluorometric analysis of CD4, CD8 and the T cell antigen receptor (TCR alpha beta) clearly demonstrated that normal rat thymocytes contain CD4-8+ TCR alpha beta- and CD4+8- TCR alpha beta- cells. After GC treatment, we observed significant increases in the percentages of CD4-8+ TCR alpha beta- and CD4+8- TCR alpha beta- cells. The extent of the increase in the percentage of CD4-8+ TCR alpha beta- cells was greater than that of CD4+8- TCR alpha beta- thymocytes. Two-color analysis of TCR alpha beta and major histocompatibility complex (MHC) class I antigen showed that GC treatment significantly increased the percentage of TCR alpha beta- MHC class Ihi cells. Three-color analysis of CD4, CD8 and MHC class I demonstrated that normal rat thymocytes contain CD4-8- MHC class Ihi cells, which increased in number after GC treatment. These results indicate that rat thymocytes contain no fewer CD4-8+ TCR alpha beta- and CD4+8- TCR alpha beta+ cells than do mouse thymocytes, and that CD4-8+ TCR alpha beta- cells predominate over CD4+8- TCR alpha beta- cells in LEW rat thymus. Rat CD4-8- cells seemed to be divided into two subsets of TCR alpha beta- MHC class Ihi and TCR alpha beta- MHC class I- cells.

Effects of FK506 on rat thymic microenvironment in thymocyte maturation, proliferation, and mobilization

THYMOCYTES are divided into four major populations: CD4CD8, CD4CD8, CD4CD8, and CD4CD8 thymocytes. Immature thymocytes develop into mature thymocytes through the expression of T cell receptors (TCR). These developmental sequences in phenotypic and TCR expression are considered important for the production of mature thymocytes. FK506 or Tacrolimus, which is a macrolide antibiotic produced by Streptomyces tsukubaensis, is a strong immunosuppressant drug that has been widely used for renal and other organ transplantations. In several studies it has been observed that FK506 also affects the thymus in rodent models. We have analyzed and reported the effects of FK506 on rat thymocytes using immunohistochemical stainingand 3–color flow cytofluorometry. In this study we also investigated and presented the effects of FK506 on rat thymic tissues analyzing the vascular structures in the thymus.

Effect of Oral Adsorbent AST‐120 on Cyclosporin Absorption in Rats

The oral adsorbent AST‐120 is used to inhibit the progression of renal failure by adsorbing uraemic toxins in the gastrointestinal tract. When AST‐120 is administered to patients receiving immunosuppressive medicines, it is important to study the effect of AST‐120 on the amount of these and other drugs absorbed. We have, therefore, studied the in‐vitro adsorption of cyclosporin by AST‐120 and investigated the effect of oral administration of AST‐120 on the absorption of cyclosporin in rats.

Effects of tacrolimus on rat thymic epithelial cells.

FK506 is an immunosuppressive agent that was discovered in Japan. Many experiments on organ transplantation have shown the prolongation of allograft survival in animals by treatment with FK506. Previous studies have also shown that FK506 has a remarkable immunosuppressive effect and improves the outcome of liver transplantation. We recently analyzed the effect of FK506 on thymocyte differentiation by the immunoperoxidase technique and flow cytometry using monoclonal antibodies (MoAbs) for thymus and T-cell surface antigens, and we found a reduction of major histocompatibility complex (MHC) class II antigen expression on thymic epithelial cells. Our results have suggested that FK506 inhibited thymocyte differentiation in rats by not only directly but also by indirectly acting on thymic epithelial cells. In the present study, we investigated the effect of FK506 on rat thymic epithelial cells by immunohistochemistry using various MoAbs.