Immunological properties of dinitrophenyl derivatives of beta-subunit of the human chorionic gonadotropin

Characterization of antibodies to a placenta-specific antigen cross-reacting with a choriocarcinoma cell line

Antibodies were raised in rabbits to purified human term placental villous plasma membrane. These were cytotoxic to human peripheral blood lymphocytes and manifested cross-reactivity to kidney and liver. After absorption with these tissues, reactivity was retained with placental villous plasma membrane. The placental-specific antiserum was fully reactive with BeWo choriocarcinoma cells, but was devoid of reaction with a human myeloma tumor cell line (GM2132). The antibodies were cytotoxic to BeWo in the presence of complement, as determined by trypan blue uptake, 51Cr release, and inhibition of uptake of 3H-thymidine.

Characterization of anti oLH beta-antibodies acting as contraceptives in rhesus monkeys. I. In vitro binding properties

Female monkeys actively immunized with oLHbeta are infertile when circulation antibody titers become sufficiently high to bind 30% of an iodinated hCG standard. We report here the extensive characterization of the oLHbeta antibodies. Their binding affinity and capacity for human and rhesus gonadotropins were determined. The affinity was high (Ka - 10(9) M-1) and was similar for high, medium and low titer antisera. In contrast, the binding capacity for hCG correlated well with antibody titers (n = 18, r = 0.888, P less than 0.001) and ranged from 0.09 to 8.3 x 10(-7)M. Column chromatographic analysis showed that anti-oLHbeta was mostly IgG. A temporal increase of affinity ('maturation') after booster was absent in the majority of monkeys. Cross-reaction between hCG and hLH as well as rhCG and rhLH was high. The latter, however, did not interfere with regular cycles and ovulation, suggesting that oLHbeta may be a useful antigen for human contraception.

Clinical and immunological responses with Pr- beta-hCG-TT vaccine

Six different batches of Pr-beta-hCG-TT vaccine have been evaluated in 23 women for the antibody response. The anti-sera formed against these conjugates were capable of reacting immunologically with the whole hCG in radioimmunoassays and also neutralized the biological activity of hCG in radioreceptor assays. The antibody titres attained peak levels 4-6 months after the first injection. The peak titres could not be sustained and most of the subjects showed a spiky pattern. One subject was considered as non-respective, two others had fairly low titres. Amongst the conjugates tested, batch 108 with SPLPS (sodium pthalate denatured with lipo-polysaccharides from S. entritides) seemed more promising, but the addition of the adjuvant was found to be pyrogenic and unlikely to be accepted clinically.

Immunogenicity of three C-terminal synthetic peptides of the beta subunit of human chorionic gonadotropin and properties of the antibodies raised against 45-amino acid C-terminal peptide

Immunological studies were carried out in rhesus monkeys and rabbits on three C-terminal synthetic peptides of beta-hCG (115-145; 111-145 and 101-145) after conjugating these to tetanus toxoid (TT). The immunogenicity of the peptide conjugates was comparatively poorer with reference to Pr-beta-hCG-TT conjugates at similar doses and immunization schedule. Amongst the three peptides, the best response was obtained with the 45-amino acid c-terminal peptide (45-CTP; 101-145). The anti-45-CTP recognized native hCG and was devoid of cross-reaction with hLH. hCG-induced testosterone production by mouse Leydig cells was inhibited by anti-45-CTP antiserum, although its neutralization capacity decreased more rapidly upon dilution than anti-beta-hCG sera of comparable titres. Immune complexes formed by the anti-45-CTP with hCG had a lower sedimentation value than those formed by anti-beta-hCG antisera with hCG, suggesting the presence of a limited number of immuno-determinant regions in the 45-amino acid C-terminal synthetic peptide.