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 immuno-fluorometric assay. The isohormone distributions of i njected FSH materials were analyzed by chromatofocusing. Serum samples were collected before, and 6, 24, and 72 hours after 300 IU of recomb inant or urinary FSH. Volunteers: Fifteen gonadotropin-deficient subje cts (8 women and 7 men) received recombinant FSH and 8 of them (4 wome n and 4 men) received an equal dose of urinary FSH. Results: No signif icant differences were apparent between the bioactive FSH levels after recombinant and urinary FSH treatments (n = 8). The immunroeactive FS H levels at 72 hours after urinary FSH were significantly higher than after recombinant FSH injection with values (median and range) of 3.80 (2.76 to 5.75) IU/L (IRP 78/549) and 3.10 (1.78 to 4.95) IU/L, respec tively. There were no significant changes in the bioactive to immunore active ratios of FSH within time and between sexes after either recomb inant FSH (n = 15) or urinary FSH (n = 8). However, the bioactive to i mmunoreactive ratio of the FSH material injected and of the post-treat ment serum samples were both higher after recombinant FSH than after u rinary FSH injection. Chromatofocusing revealed that injected recombin ant FSH contained more activity in the basic fractions than urinary FS H. Conclusions: Recombinant human FSH maintains its biological activit y when injected into gonadotropin-deficient subjects. The bioactive to immunoreactive ratio of recombinant FSH was higher than that of urina ry FSH indicating that recombinant FSH contains relatively more basic isohormones, and this finding was strengthened by chromatofocusing.