Restricted entry of IgG into male and female rabbit reproductive ducts following immunization with recombinant rabbit PH-20.
OBJECTIVE
Successful immunocontraception using sperm antigens is dependent on achieving sufficient sperm-specific antibody in the reproductive ducts to prevent fertilization. The blood: luminal barrier of the male and female reproductive ducts must be overcome for this to occur. We have, therefore, investigated the relative titers of antigen-specific immunoglobulin G (IgG) in luminal fluids collected from male and female rabbit reproductive ducts following immunization with recombinant rabbit PH-20 (rPH-20).


METHODS
Male and female rabbits were immunized subcutaneously with rPH-20 in Freund's adjuvant. Reproductive tract fluids and plasma were collected and assayed for specific IgG by enzyme-linked immunoabsorbent assay (ELISA). Plasma anti-rPH-20 antibodies were tested for their ability to inhibit in vitro fertilization.


RESULTS
Plasma rPH-20-specific IgG titers of > 21 x 106 were induced in bucks. Antibody levels in the rete testis and cauda epididymidis fluids were only 0.026 and 0.168% of plasma levels, respectively. Plasma IgG titers were > 30 x 10(6) in does, but antibody levels in free flow vaginal fluid, free flow uterine fluid and free flow oviduct fluid were only 0.016, 0.078 and 0.072% of plasma levels, respectively. Induction of ovulation by administration of human chorionic gonadotrophin (hCG) significantly increased rPH-20-specific IgG only in free flow vaginal fluids. Plasma antibody from immunized rabbits inhibited in vitro fertilization but conception rates following mating of rPH-20 immunized male to untreated female rabbits were not affected.


CONCLUSIONS
The IgG antibody entry into the reproductive ducts of both male and female rabbits is restricted to less than 0.2% of levels induced in plasma following subcutaneous immunization. This finding raises doubts about the suitability of rPH-20 to induce immunocontraception in rabbits using strategies optimized for induction of a serum antibody response. Whether mucosal immunization strategies can achieve this remains to be tested.
Pomering
M
M
Department of Biological Sciences, Faculty of Science and Mathematics, The University of Newcastle, Australia.
Jones
Russell C
RC
Holland
Michael K
MK
Blake
Anita E
AE
Beagley
Kenneth W
KW
D000818:Animals; D015815:Cell Adhesion Molecules / Q000276:immunology*; D003269:Contraception, Immunologic / Q000379:methods*; D005260:Female; D005835:Genitalia / Q000276:immunology*; D006821:Hyaluronoglucosaminidase; D007114:Immunization; D007074:Immunoglobulin G / Q000378:metabolism*; D008297:Male; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology; D012737:Sex Factors; D014614:Vaccines, Synthetic / Q000276:immunology*
D015815:Cell Adhesion Molecules; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; D006821:Hyaluronoglucosaminidase; C066852:hyaluronidase PH-20