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Multiple forms of follicle stimulating hormone: Specific measurement and physiological significance of bioactive forms using monoclonal antibodies

Sesay, Abdul Karim; (1990) Multiple forms of follicle stimulating hormone: Specific measurement and physiological significance of bioactive forms using monoclonal antibodies. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Analytical techniques in clinical chemistry for the estimation of polypeptide hormone concentrations in biological fluids are changing from limited reagent, radioimmunoassay methods to excess reagent immunoradiometric methods, with a consequential improvement in sensitivity, precision and speed. With the advent of techniques for producing monoclonal antibodies, an additional principle could be added: production and selection of two or more antibodies directed against spatially distant sites on a single hormone or analyte. Monoclonal antibodies have successfully been raised to human glycoproteins. In this investigation, monoclonal antibodies to follicle stimulating hormone were carefully selected and produced in quantity. Their availability has allowed the development of a sensitive, non-competitive, sandwich type radioimmunoassay for human follicle stimulating hormone (hFSH). The same combination of monoclonal antibodies has been used to develop a more sensitive time resolved immunofluorometric assay for hFSH. Immunoassays for FSH have not been satisfactorily standardised. This is because FSH is not an homogeneous molecular species. It is now well known that the anterior pituitary gland of many species including man, synthesise and secrete FSH in multiple heterogeneous forms. These isohormones exhibit differences in carbohydrate composition, receptor binding activity, plasma half life and in-vitro and in-vivo bioactivity. A column isoelectric technique was standardised and this technique of chromatofocusing was used to separate the different isoforms of FSH according to their isoelectric point (pi). The biological activities of these different forms were determined using a sensitive and specific in-vitro bioassay developed in the course of this study. The assay is based on immature rat granulosa cells producing plasminogen activator in response to hFSH. The optimised bioassay has been demonstrated to result in increased specificity and sensitivity. I have utilised the assay in the measurement of FSH-like bioactivity in sera of normal volunteers and pathological samples. It has been shown in this thesis that the hFSH isoforms at a basic margin of distribution have a higher biological (as determined by the in-vitro bioassay), to immunological (as determined by a commercial RIA and an in house IRMA) ratio than the isoforms in the more acidic range of distribution. The monoclonal antibodies I have developed and characterised immunologically have been used, in association with the in-vitro bioassay, to neutralise or extract FSH bioactivity from serum samples and standards. These methods have been used to ascertain whether our monoclonal antibodies to hFSH are selective in binding predominantly to the biologically active isoforms of FSH. Our current knowledge of hFSH microheterogeneity and the assays available indicates the urgent need to select antibodies with specific binding to the biological active forms of the hormone. Assays using such bio-specific antibodies would be useful in allowing the measurement of circulating bioactive hFSH and will provide a convenient tool to advance the studies on the role of hFSH in the neuroendocrine control of gonadal maturation and reproductive cycles, and in optimisation of hFSH type and dosage used in the treatment of infertility

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Multiple forms of follicle stimulating hormone: Specific measurement and physiological significance of bioactive forms using monoclonal antibodies
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Pure sciences; Biological sciences; Hormone concentrations
URI: https://discovery.ucl.ac.uk/id/eprint/10110012
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