Evidence that luteinizing hormone-releasing hormone statin from ovine rete testis fluid is immunologically related to alphaC inhibin

A new method to discriminate immunogen-specific heavy-chain homodimer from heterotetramer immunoglobulin G directly in immunized dromedary whole plasma proteins: Western ligand blotting

The variable domain of heavy-chain camelid antibodies (VHH), exclusively present in the homodimer IgGs (HC IgG), provides valuable ligands for diagnosis, imaging and therapy. These VHHs are efficiently produced from lymphocytes of immunized animals through phage display and recombination biotechnology. For VHH development it is desirable to identify animals with high affinity HC IgG response by monitoring antigen-binding in the course of immunization. The aim of this study was to propose a direct approach on whole plasma samples to distinguish between homodimer IgG and heterotetramer (IgG(1)) responses, and quantify them, using western ligand blotting (WLB). WLB consists here in electrophoretic separation of the target IgG subclasses on the basis of molecular size and binding of (125)I labeled antigen. First, we established the WLB parameters for titration of antigen-binding homodimers in relation to antigen-binding total IgGs in ovalbumin-immunized dromedary plasma samples and demonstrated that the WLB is an alternative to ELISA for IgG subclass titration. As purification of IgG subclasses or availability of IgG subclass-specific antibodies is not necessary, WLB is more direct and practical for screening a large number of samples. Second, WLB was applied to study the pattern of homodimer and heterotetramer responses during the time-course of immunizations against three different types of immunogens. As these patterns can differ between animals and immunogens, the method may be useful for identifying animals displaying the desired antigen-specific homodimer IgG response. Lastly, WLB was also described in its variant form of dot ligand blotting for identifying antigen-binding phages at the final step of a phage display experiment.

Plasma LH, FSH, testosterone, and age at puberty in ram lambs actively immunized against an inhibin alpha-subunit peptide

Active immunization against inhibin has been shown to advance puberty and increase ovulation rate in ewe lambs; but in ram lambs, effects on puberty and sperm production are equivocal. The objective of the present study was to determine whether active immunization against an inhibin alpha-subunit peptide advances the onset of puberty in ram lambs. St. Croix hair sheep ram lambs were assigned to inhibin-immunized (n = 7) and control (n = 8) treatment groups. Lambs in the inhibin-immunized group were immunized against a synthetic peptide-carrier protein conjugate, alpha-(1-25)-human alpha-globulin (halpha-G), and control lambs were immunized against halpha-G. Lambs were immunized at 3, 7, 13, 19, 25, 31, and 37 weeks of age. On the day of immunization a blood sample was collected and lambs were weighed. Another blood sample was collected 1 week following each immunization. At 20 weeks of age additional blood samples were collected at 20 min intervals for 8h. Beginning at 20 weeks of age and at weekly intervals thereafter, scrotal circumference (SC) was measured and semen was collected using electroejaculation. A subsequent ejaculate was collected 1 week following onset of puberty, which was defined as the week of age when an ejaculate first contained > or =50 x 10(6) sperm cells. In control lambs, plasma alpha-(1-25)-antibody (Ab) was nondetectable. In inhibin-immunized lambs, alpha-(1-25)-Ab titer increased from 7 to 25 weeks of age and then plateaued at a level that varied (P<0.001) among animals. Body weight and SC of control and inhibin-immunized lambs were similar at the onset of puberty. At pubertal onset inhibin-immunized lambs were older than control lambs (31.9+/-0.5 vs. 29.5+/-0.7 weeks of age, P<0.05). Plasma FSH concentrations were similar in control and inhibin-immunized lambs from 3 to 38 weeks of age. Plasma LH levels were lower (P<0.01) in inhibin-immunized than control lambs. During the 8-h blood sampling period at 20 weeks of age, LH and testosterone concentrations were lower (P<0.05) in inhibin-immunized than control ram lambs, and the LH pulse frequency was similar in the two groups of animals. The decreased LH secretion is consistent with the immunoneutralization of a putative inhibin alpha-subunit-related peptide that stimulates LH secretion in ram lambs. Present findings show that active immunization against an inhibin alpha-peptide delays rather than advances puberty in ram lambs.