Unbound FS was measured in 96-well plates that were coated with 4 ^g/ml of the monoclonal antibody 6FS7. Standards and samples were added coincident with a bio-tinylated secondary antibody, monoclonal 7FS30. The an-tibody-antigen mixture was allowed to incubate overnight on a shaker at room temperature. After an overnight incubation, the plate was washed and incubated with HRP-streptavidin. The enzyme was incubated for 2 h and the plate was then washed; substrate (orthophenylene diamine) was added, and the samples were read at 490 nm. Recombinant human FS was recovered (>95%) in buffer or urine. Total FS was measured using an assay previously described. Both assays used rh-FS288 as standard. buy cipro
Inhibin A and inhibin B assay kits were purchased from Serotec (Oxford, England); the characteristics of these dimer-specific assays have been previously described. The assays were validated within the laboratory using rh-inhibin A, rh-inhibin B, rh-activin A, and rh-activin B. The inhibin A standard was the World Health Organization-National Institute for Biological Standards and Control (91/ 624).