Publication: New approaches to immunological contraception
Issued Date
1979-12-01
Resource Type
ISSN
03063356
Other identifier(s)
2-s2.0-0018615378
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Mahidol University
Rights Holder(s)
SCOPUS
Bibliographic Citation
Clinics in Obstetrics and Gynaecology. Vol.6, No.3 (1979), 531-548
Suggested Citation
P. Matangkasombut New approaches to immunological contraception. Clinics in Obstetrics and Gynaecology. Vol.6, No.3 (1979), 531-548. Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/13219
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Title
New approaches to immunological contraception
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Abstract
Substances exist which are unique to the reproductive system and active or passive immunization of experimental animals with some of these substances has led to antifertility effects. Although these results have been encouraging, attempts to develop a contraceptive vaccine have met with several difficulties. A high degree of antifertility efficacy is necessary and this has proved difficult to achieve. Several potential candidate antigens have had to be dropped because of poor immunogenicity; other substances with reasonable immunogenicity in heterologous models may prove to be poorly immunogenic in homologous immunization. Apparently, a natural state of immunological tolerance may exist at least in relation to some of these substances, particularly those which are present during ontogenic development of the immune system. Potential immunological hazards of immunization with material derived from human sources necessitate the exercise of extreme caution in the development of a contraceptive vaccine. In order to eliminate these hazards, the principle has been established to avoid the use of material as target antigens which are normally present in tissue constituents or which contain determinants common to normal tissue antigens. This requires detailed knowledge of the exact chemical nature of potential antigens. In addition, exhaustive safety testing in experimental animals including subhuman primates must be carried out before proceeding to clinical trials in humans. Despite these obstacles, considerable progress has been made. The problem of potential immunological hazards has been circumvented by selecting truly unique substances of the gametes or early conceptus and encouraging results have been obtained with LDH-X and hCG. Although hCG shares antigenic determinants with pituitary hormones - which precludes the use of the whole hormone or its β subunit - it possesses a unique peptide at its C-terminus. This small peptide is poorly immunogenic even in heterologous species such as the baboon; however, significant progress has been made in improving its immunogenicity by conjugating it to suitable carrier molecules and by using appropriate adjuvants. Whether these current efforts will overcome the problem of immunogenicity in homologous immunization in man and also satisfy the stringent safety criteria for a contraceptive vaccine remains to be seen. Progress in the characterization of membrane antigens of the sperm, ovum and trophoblast has been slow. However, current efforts may eventually reveal that these and other target antigens are suitable for an immunological attack.