PT  - JOURNAL ARTICLE
AU  - J E Low
AU  - I Jardine
TI  - A novel cyclosporine binding assay.
DP  - 1986 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 39--45
VI  - 238
IP  - 1
4099  - http://jpet.aspetjournals.org/content/238/1/39.short
4100  - http://jpet.aspetjournals.org/content/238/1/39.full
SO  - J Pharmacol Exp Ther1986 Jul 01; 238
AB  - 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.