Studies on human placental proteins

Kukulska-Langlands, Beata Maria (1980) Studies on human placental proteins. PhD thesis, University of Glasgow.

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Abstract

Maternal antibodies to placental-specific antigens were not detected in third trimester maternal sera or in concentrated material adsorbed from maternal sera on a placental affinity column using immuno-fluorescence and gel precipitation techniques, A method was described for the dissociation of antigens of less than 100,000 daltons from soluble antibody-antigen complexes. This method was applied successfully to the dissociation of albumin-anti-albumin complexes formed in antigen excess. Application of this method to pregnancy serum followed by immunisation of rabbits with the dissociated material resulted in anti-SP1 response detectable on AACE. The molecular weight of SP1 is approx, 100,000 daltons and the bulk of SP1 was detectable in the retentate at the end of the dissociation. This argued against a conclusion that SP1 had been dissociated from immune complexes. Immunisation of rabbits uith soluble extract of a placenta which had been adsorbed over anti-human serum column induced AACE-detectable responses to very few serum proteins, PAPP-A, HPL, SP1 and several unidentified antigens found in placental tissue. Placental soluble extract which had in addition been adsorbed over anti-human lung column and anti-human amniotic fluid column induced responses to very few serum proteins, PAPP-A and HPL, Using these latter antisera two other antigens were identified in placental soluble extract (antigens a and b) which were not detectable in lung soluble extract or in non-pregnant serum. Antigen was also detected in pregnancy serum. By contrast, immunisation with unfractionated placental soluble extract induced extensive anti-serum response, anti-HPL and anti-SP1 but no detectable anti-PAPP-A response. The extent to which several serum proteins were denatured by a variety of commonly used dissociants of antibody-antigen complexes UBS assessed by changes in the protein's precipitating behaviour on one-dimensional AACE. AACE was found to be superior for this to double immunodiffusion. The smaller proteins studied were more resistant to irreversible denaturation, but the sample size was too small to seek a general relationship between molecular weight and denaturation. All proteins examined proved resistant to one hour exposure to 1o5 n KI-PBS and to pH 11 buffer. 1o5 n KI-PBS was used in the purification of PAPP-A by antibody affinity chromatography followed by DEAE-cellulose ion exchange and Sepharose 6B gel filtration. Double AACE arcs formed by PAPP-A in term maternal serum were also formed by partially-purified PAPP-A indicating that the antigenic variants had not been separated. The purification product contained PAPP-A which was 427-fold purified in terms of immunological reactivity on AACE, The high degree of purity was also suggested by studies with the radiolabelled purification product, 125I-PAPP-A was shown to have similar molecular weight and electro-phoretic mobility to maternal serum PAPP-A, Immune-precipitated [125]I-PAPP-A was analysed by 5% and 3% SDS-PAGE and found to contain a major radioactive component of approx, 180,000 daltons and a minor component of between 74,-93,000 daltons. The nature of the minor component has not been determined. It may be tentatively concluded that PAPP-A (mol. wt. 750,000) contains polypeptide subunits of approx. 180,000 daltons and may therefore be composed of up to four such subunits, A collaborative clinical study in which PAPP-A was assayed in the blood of women during the third trimester of pregnancy by AACE suggested that fetal sex may affect PAPP-A levels with males giving rise to higher levels than females. No significant difference in the levels of PAPP-A was detected when patients with babies affected with intrauterine growth retardation were compared with controls. No significant change in the mean concentration of PAPP-A was detected in the group of patients with gestational diabetes, but some very high values were found in this group. In the group of patients with insulin-controlled diabetes the mean concentration of PAPP-A was significantly reduced.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QH Natural history > QH426 Genetics
Q Science > QR Microbiology
Colleges/Schools: College of Medical Veterinary and Life Sciences
Supervisor's Name: Sutcliffe, Dr. Roger
Date of Award: 1980
Depositing User: Mrs Marie Cairney
Unique ID: glathesis:1980-40979
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2019 13:03
Last Modified: 30 Jan 2019 13:21
URI: http://theses.gla.ac.uk/id/eprint/40979

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