CIRCULATING BIOACTIVE AND IMMUNOREACTIVE RECOMBINANT HUMAN FOLLICLE-STIMULATING-HORMONE (ORG-32489) AFTER ADMINISTRATION TO GONADOTROPIN-DEFICIENT SUBJECTS

Objective: To study the bioactivity of recombinant and urinary human F SH after single IM injection into gonadotropin-deficient subjects. Des ign: Serum FSH levels were measured by immature rat granulosa cell bio assay and immunofluorometric assay. The isohormone distributions of in jected FSH materials were analyzed by chromatofocusing. Serum samples were collected before, and 6, 24, and 72 hours after 300 IU of recombi nant or urinary FSH. Volunteers: Fifteen gonadotropin-deficient subjec ts (8 women and 7 men) received recombinant FSH and 8 of them (4 women and 4 men) received an equal dose of urinary FSH. Result(s): No signi ficant differences were apparent between the bioactive FSH levels afte r recombinant and urinary FSH treatments (n = 8). The immunoreactive F SH levels at 72 hours after urinary FSH were significantly higher than after recombinant FSH injection with values (median and range) of 3.8 0 (2.76 to 5.75) IU/L (IRP 78/549) and 3.10 (1.78 to 4.95) IU/L, respe ctively. There were no significant changes in the bioactive to immunor eactive ratios of FSH within time and between sexes after either recom binant FSH (n = 15) or urinary FSH (n = 8). However, the bioactive to immunoreactive ratio of the FSH material injected and of the post-trea tment serum samples were both higher after recombinant FSH than after urinary FSH injection. Chromatofocusing revealed that injected recombi nant FSH contained more activity in the basic fractions than urinary F SH. Conclusion(s): Recombinant human FSH maintains its biological acti vity when injected into gonadotropin-deficient subjects. The bioactive to immunoreactive ratio of recombinant FSH was higher than that of ur inary FSH indicating that recombinant FSH contains relatively more bas ic isohormones, and this finding was strengthened by chromatofocusing. (C) 1994 by American Society for Reproductive Medicine.