Abstract
The binding of [3H]cyclosporine A (CsA) to BALB/c mouse spleen cells was examined with a novel centrifugation assay which rapidly removes free [3H]CsA from cell surfaces with a minimal loss of low affinity specifically bound [3H]CsA. A single class of specific and saturable CsA binding sites was found under equilibrium binding conditions. Scatchard analysis of the data resulted in a straight line with KD and Bmax values of 95 nM and 2.4 million binding sites/cell, respectively. Kinetic studies conducted with a wider range of [3H]CsA concentrations revealed two distinct binding sites, with KD's of 290 nM and 9.6 microM, respectively. [3H]CsA bound only nonspecifically to phosphatidylcholine:cholesterol liposomes. Specific [3H]CsA binding sites were found in murine WEHI-5 B-lymphoma cells, murine N1E-115 neuroblastoma cells and human A204 rhabdosarcoma cells. We conclude from these results that there are at least two nonlipid CsA binding sites in BALB/c mouse spleen cells and that CsA binding sites are present in both lymphoid and nonlymphoid tissue.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|