RESUMO
The presence of androgen binding sites [five alpha dihydrotestosterone [5%-DHT]] on NZB/BALBc mouse peritoneal macrophages [M phi] was identified. Cells were incubated with different concentrations of [3H]-5 alpha-DHT in the presence or absence of a 100 fold excess of unlabelled 5 alpha-DHT to correct for nonspecific binding. Labelled cells were separated from unbound steroid by immunomagnetic beads coated with rat anti-mouse M phi antibody [rat anti-mouse F4/80 Ag]. The binding identified in the mouse M phi was highly selective towards androgenic compounds. Little competition was seen from 17 beta oestradiol [17beta E2] or the synthetic glucocorticoid triamcinolone acetonide. Binding data derived from Scatchard analysis showed the presence of a high affinity androgen binding species. The dissociation constant [Kd] value for the receptor was calculated to be 4.7x10[-9]M. The number of receptors per cell was 2950