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An indirect ELISA with peptides containing the GP5 neutralization epitope was used to measure the time courses of formation of neutralizing antibodies in sera of groups of 10 pigs infected with seven different strains of porcine reproductive and respiratory syndrome virus (PRRSV) generated in an earlier study (Johnson et al., Vet.Immunol. Immunopath. 102:233-247. 2004). The neutralizing antibody responses varied greatly between individual pigs infected with each PRRSV strain. Some pigs generated high titers of neutralizing antibodies between 7 and 28 days post infection (p.i), whereas other pigs had not generated a significant response by 42 days p.i. The heterogeneity in antibody formation in individual pigs also pertained to anti-N-protein antibody formation as measured by both HerdCheck and peptide ELISAs and there was no correlation between anti-N-protein and neutralizing antibody formation. Also, viremia was disconnected from neutralizing antibody formation. Viremia peaked 7-15 days p.i. and then precipitously declined to undetectable levels in most infected pigs by 21-28 day p.i. whether or not they had generated neutralizing antibodies. Furthermore, contrary to an earlier conclusion from this study the formation of neither neutralizing nor anti-N-protein antibodies was related to viral load as measured by infectious virus levels in serum.
Antiphospholipid antibodies (APA) and anti-idiotypic antiphospholipid antibodies (AiAPA) were studied in 148 women subjected to IVF. APA (IgG aCL, aPS,) levels in serum have been defined. Sera IgG fraction was also examined for the presence of AiAPA by three different methods: 1) binding of AiAPA with mouse monoclonal cofactor-independent APA (mAPA) immobilized on plate; 2) AiAPA neutralization of human affinity isolated APA and 3) mAPA binding with phospholipids. Significant difference in AiAPA levels between APA+ and APA- women subjected to IVF have been found. The mean level of AiAPA was lower in APA women subjected to IVF than in APA- women from the same group (p < 0.05). IV infusion of Ig decreased the APA level significantly as well as increased the AiAPA level in APA+ women subjected to IVF. Ig application to incubation in vitro results in decrease of APA levels in serum. Results of this study confirmed possibility of AiAPA participation in down regulation of cofactor-independent APA production in women undergoing to IVF.
The formation of 19S antibody to poliovirus by rabbit spleen cells in vitro was interrupted by adding actinomycin D (1 to 10 micrograms per milliliter) for 30 minutes or longer. Shorter treatment (5 to 15 minutes) caused partial suppression. Antibody formation was slowly renewed upon removal of the drug. These results suggest that 19S antibody formation is contingent upon DNA-dependent RNA synthesis and that the genetic messenger has an average lifetime of one-half day or less. Treatment with chloramphenicol (20 to 50 micrograms per milliliter) for 3 days caused the cessation of 19S antibody formation.
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Injection of a small bacteriophage phiX 174 into guinea pigs results in an accelerated elimination of phage detectable as early as 24 hours after injection. The immune nature of the accelerated elimination is indicated by its specificity, by the appearance of excess specific serum antibody after phage elimination, and by the prevention of accelerated elimination by 400 r whole body x-irradiation of guinea pigs prior to injection of phage. The early antibody response is considered to be a primary one since an analogous response occurs in newborn guinea pigs, antibody is not detectable in the sera of non-immunized animals, and the second challenge with phiX stimulates a serum antibody response 100-fold greater than that after primary immunization. The early detection of immune elimination appears to be due, in part, to the small amounts of phage employed, since larger doses of phage delay the time of onset of detectable immune elimination. The early rise of serum antibody in the primary and secondary response appears exponential with a similar rate constant of antibody formation. The rate constant is also independent of dose. These findings have led to the suggestion that during this exponential phase, the relative rate of antibody formation at a cellular level may be constant for a given antigen.
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The IgE antibody response of NIH mice to ovalbumin was suppressed by in vivo complement depletion with cobra factor. This observation extends to IgE the finding that complement participates in thymus-dependent antibody formation. Control mice producing IgI anti-ovalbumin antibody after boosting all developed marked peripheral eosinophilia, whereas mice in which the IgE antibody response had been suppressed by cobra factor did not. Administration of cobra factor itself had no effect on peripheral eosinophil levels.
Anti-idiotypic antibodies have been used to mimic antigen in the mouse antiphosphorylcholine response in order to investigate the induction of precursors of antibody-forming cells. We have shown that interaction of anti-idiotype antibody with receptor antibody molecules induces the formation of antibodies that are specific for phosphorylcholine and carry the idiotypic determinants. This induction is dependent on the recognition of carrier determinants on the anti-idiotype antibody by helper T cells. We conclude that receptor antibody molecules on the surface of the precursors of antibody-forming cells deliver the antigenic signal for the induction of these cells.
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Monoclonal IgY have the potential to become unique tools for diagnostic research and therapeutic purposes since avian antibodies provide several advantages due to their phylogenetic difference when compared to mammalian antibodies. The mechanism of avian immunoglobulin gene diversification renders chicken an excellent source for the generation of recombinant scFv as well as Fab antibody libraries of high diversity. One major limitation of these antibody fragments, however, is their monovalent format, impairing the functional affinity of the molecules and, thereby, their applicability in prevalent laboratory methods. In this study, we generated vectors for conversion of avian recombinant antibody fragments into different types of bivalent IgY antibody formats. To combine the properties of established mammalian monoclonal antibodies with those of IgY constant domains, we additionally generated bivalent murine/avian chimeric antibody constructs. When expressed in HEK-293 cells, all constructs yielded bivalent disulfide-linked antibodies, which exhibit a glycosylation pattern similar to that of native IgY as assessed by lectin blot analysis. After purification by one step procedures, the chimeric and the entire avian bivalent antibody formats were analyzed for antigen binding and interaction with secondary reagents. The data demonstrate that all antibody formats provide comparable antigen binding characteristics and the well established properties of avian constant domains.
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A fraction stimulating antibody formation in neonatal animals was obtained in separation of the calf thymus extract (1A) prepared by the method of Goldstein et al. on a column with Sephadex G-25 (fine). Testing of the activity of analogous fractions of the extracts of calf tonsils, spleen, lymph nodes and the liver led to a supposition that the thymus was the only source of specific humoral factor stimulating antibody formation, which could accumulate in the peripheral lymphoid formations. Low activity of tonsillar extracts failed to confirm the hypothesis on the role played by the tonsils as the central immunity organ similar to the bursa Fabricii.
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Reaginic antibodies to the benzylpenicilloyl determinant (BPO) and ovalbumin (OA) were induced readily in B6D2F1 mice by a single i.p. injection of either 1 or 10 mug of BPO4-OA suspended with 1 mg of Al(OH)3 in 0.5 ml of saline. Administration of conjugates consisting of the hapten coupled to the isologous, nonimmunogenic murine gamma-globulins (MgammaG), i.e., BPO9-MgammaG, BPO11-MgammaG, or BPO12-MgammaG, resulted in complete and specific suppression of the induction of the anti-BPO reaginic antibody response without affecting, however, the level of reaginic antibodies to OA. Further study of the effect of epitope density on the immunologic properties of BPOX-MgammaG revealed that a) the lightly haptenated conjugated, BPO1-MgammaG and BPO2.9-MgammaG, were not immunosuppressive, b) the conjugates, BPO4.3-MgammaG and BPO19-MgammaG, were partially tolerogenic, and c) the heavily haptenated conjugate, BPO31-MgammaG, was nontolerogenic. Moreover, most importantly, the ongoing anti-BPO response in sensitized mice was readily abrogated by either four daily or four weekly injections of BPO9-MgammaG. The immunosuppressive effect of BPO12-MgammaG conjugates was dose dependent, complete suppression being achieved with 200 mug of the tolerogen. The unresponsiveness to BPO of spleen cells from immunosuppressed donors was also maintained in adoptive cell transfer experiments in spite of the additional administration of the immunizing antigen under conditions expected to yield a secondary IgE response. Hence, it is suggested that, with special precautions to prevent unleashing an anaphylactic shock, treatment of penicillin-sensitive individuals with polyvalent conjugates of an appropriate number of BPO groups per human gamma-globulin molecule would constitute a rational immunotherapeutic procedure for the abrogation of the allergic response to BPO.