Cyclosporine inhibition of CH series murine B-cell lymphomas

Ly-6 superfamily members Ly-6A/E, Ly-6C, and Ly-6I recognize two potential ligands expressed by B lymphocytes

Most hemopoietic cells express one or more members of the Ly-6 supergene family of small glycosylphosphatidylinositol-linked proteins. Although levels of Ly-6 proteins vary with stages of differentiation and activation, their function largely remains unknown. To ascertain whether ligands for Ly-6 proteins exist, chimeric proteins were constructed in which Ly-6E, Ly-6C, and Ly-6I were fused to the murine IgM heavy chain. These chimeras specifically stained both developing and mature B lymphocytes, as assessed by flow cytometry. Analysis of variants of the CH27 B cell lymphoma revealed that Ly-6A/E and Ly-6I recognized different molecules. CH27 cells with low levels of Ly-6A/E ligand activity also lost expression of CD22, and cells transfected with CD22 gained the ability to bind the Ly-6A/E chimera and, to a lesser extent, the Ly-6C and Ly-6I chimeric proteins. As many mature B cells coexpress Ly-6A/E and CD22, the function of Ly-6 molecules may be to associate with other membrane proteins, possibly concentrating these ligands in lipid rafts, rather than acting directly as cell:cell adhesion molecules.

A comparative study on immunosuppressive effects of cyclosporin A and FK 506 on peripheral blood lymphocytes in dogs

Immunosuppressive effects of cyclosporin A (CsA) and FK 506 (FK) on peripheral blood lymphocytes were studied in dogs in respect to mixed lymphocyte reaction, proliferative responses to recombinant interleukin-2 (rIL-2), phytohemagglutinin (PHA) and concanavalin-A (Con-A); phenotypes of OKIa1, CD3, CD8 and surface IgM; cytotoxic activity against xenogeneic tumor cells. CsA (2.0 or 5.0 mg/kg, intravenously) or FK (0.16 mg/kg, intramuscularly) was given to mongrel dogs every morning for serial 21 days. The blood concentrations of CsA, measured as trough levels by fluorescence polarization method, ranged from 37 to 350 ng/ml in dogs administered at 2.0 mg/kg and from 170 to 894 ng/ml in dogs administered at 5.0 mg/kg during treatment, respectively. In dogs treated with FK at a dose of 0.16 mg/kg, the drug concentrations in the plasma during treatment ranged from 0.16 to 1.8 ng/ml. Mixed lymphocyte reaction and proliferative responses to rIL-2, PHA and Con-A, which were declined by CsA, were not affected by FK. In contrast, the proportion of OKIa1+ cells was not affected by CsA, whereas FK decreased the proportion of OKIa1+ cells progressively during the course of treatment. Cytotoxic activity was suppressed by both CsA and FK. These results possibly indicate that CsA and FK exert their immunosuppressive effects via different mechanisms.

An immunohistochemical study on the effects of cyclosporin on the gut-associated lymphoid tissue of rats

The effect of Cyclosporin (CS) on the gut-associated lymphoid tissue (GALT) of inbred WKA rats was immunohistochemically studied by the immunoperoxidase method. CS in olive oil was orally administered daily for seven days at the dose of 25, 50 and 100 mg/kg/day. On days 1, 4 and 7 of CS administration, rats were sacrificed under ether anesthesia. By CS administration, the decrease and disappearance of Ia antigen expression were dose-dependently recognized on the epithelial cells and the overlaying cells of Peyer's patches. The reduced cellular population and Ia expression of lymphocytes of the follicle and the disappearance of the germinal center also occurred, and Ia-positive dendritic non-lymphoid cells in Peyer's patches and endothelial cells of capillaries in the lamina propria disappeared on day 7 of CS administration. In addition, a temporary increase of W3/25-positive cells and the appearance of Ia-positive intra-epithelial cells were observed on day 4. Simultaneously, interleukin 2 receptor (IL-2R)-positive cells gradually decreased on day 4, and almost disappeared on day 7. From these results, it is speculated that CS suppresses not only interleukin 2 (IL-2) production as previously reported, but also the expression of Ia antigens and IL-2R. It may well suppress the immune system at the point of recognition and presentation of alloantigen, and the proliferation and differentiation of B cells.

Effects of cyclosporin A on cell proliferation and collagen production by human skin fibroblasts

Cyclosporin A (CSA) is a potent immunosuppressive drug that has been used clinically for the treatment of organ rejection after transplantation as well as for patients with a wide variety of immune-mediated disorders. CSA has recently been reported to be effective in systemic sclerosis, which is a disease of the connective tissues leading to fibrosis of the skin and other involved organs. In this study, we investigated whether CSA affects the cell proliferation and collagen synthesis of human skin fibroblasts. CSA inhibited the DNA synthesis and cell growth of cultured fibroblasts at concentrations of 10(-8) M to 10(-5) M in a dose-dependent manner. The production of both collagen and non-collagenous protein at both the mRNA and protein levels was not affected by 10(-8) to 10(-6) M CSA, but was decreased in the presence of 10(-5) M CSA. These results suggest that CSA may inhibit the proliferation of fibroblasts, but not their synthesis of collagenous and non-collagenous proteins at therapeutic concentrations.

The effect of cyclosporin A on epidermal cells. II. Cyclosporin A inhibits proliferation of normal and transformed keratinocytes

Cyclosporin A (CSA) is a potent immunosuppressive drug that inhibits the proliferation of activated T cells by blocking the production of interleukin 2. Recent studies have demonstrated that CSA also inhibits the proliferation of neoplastic cells of hematopoietic and nonhematopoietic origin. CSA has also been reported to be effective in the treatment of psoriasis, which is characterized by epidermal hyperproliferation. As so many of the therapeutically effective agents in psoriasis are antiproliferative, we sought to determine whether CSA affects the proliferation of keratinocytes. We studied the effect of CSA on the proliferation of normal and transformed keratinocytes and demonstrated that CSA inhibits DNA synthesis and proliferation of keratinocytes. CSA also inhibits DNA synthesis of other neoplastic cells of hematopoietic and nonhematopoietic origin. These findings indicate the CSA inhibits the proliferation of various cell types.