Expression of Y7 Cross‐Reactive Idiotope on Human IgM Molecules

The effect of influenza vaccine immunization on natural antibodies

Natural, polyreactive, low-affinity antibodies are known to play an important role not only in the immediate defense against pathogens, but also in shaping the acquired immune response. On the other hand, antigen specific, high-affinity antibodies can affect the balance of natural antibodies and lead to autoimmune diseases. In this study, we have analyzed the changes that occur in the IgM and IgG pool of natural antibodies after immunization with split or whole virion influenza vaccine. For this purpose, "in-house" developed ELISAs were used. The subjects were divided, according to the vaccination status, into those who had been immunized with the influenza vaccine in previous years and those who had been immunized for the first time. The analysis indicated that the pool of natural antibodies was not impaired by the immunization, evidenced by the lack of changes in any of the groups, and that certain fluctuations were induced in order to maintain the homeostasis of the immune system.

Anti-non-Gal-specific combination treatment with an anti-idiotypic Ab and an inhibitory small molecule mitigates the xenoantibody response

BACKGROUND

B-cell depletion significantly extends survival of α-1,3-galactosyltranferase knockout (GTKO) porcine organs in pig-to-primate models. Our previous work demonstrated that the anti-non-Gal xenoantibody response is structurally restricted. Selective inhibition of xenoantigen/xenoantibody interactions could prolong xenograft survival while preserving B-cell-mediated immune surveillance.

METHODS

The anti-idiotypic antibody, B4N190, was selected from a synthetic human phage display library after enrichment against a recombinant anti-non-Gal xenoantibody followed by functional testing in vitro. The inhibitory small molecule, JMS022, was selected from the NCI diversity set III using virtual screening based on predicted xenoantibody structure. Three rhesus monkeys were pre-treated with anti-non-Gal-specific single-chain anti-idiotypic antibody, B4N190. A total of five monkeys, including two untreated controls, were then immunized with GTKO porcine endothelial cells to initiate an anti-non-α-1,3-Gal (non-Gal) xenoantibody response. The efficacy of the inhibitory small molecule specific for anti-non-Gal xenoantibody, JMS022, was tested in vitro.

RESULTS

After the combination of in vivo anti-id and in vitro small molecule treatments, IgM xenoantibody binding to GTKO cells was reduced to pre-immunization levels in two-thirds of animals; however, some xenoantibodies remained in the third animal. Furthermore, when treated with anti-id alone, all three experimental animals displayed a lower anti-non-Gal IgG xenoantibody response compared with controls. Treatment with anti-idiotypic antibody alone reduced IgM xenoantibody response intensity in only one of three monkeys injected with GTKO pig endothelial cells. In the one experimental animal, which displayed reduced IgM and IgG responses, select B-cell subsets were also reduced by anti-id therapy alone. Furthermore, natural antibody responses, including anti-laminin, anti-ssDNA, and anti-thyroglobulin antibodies were intact despite targeted depletion of anti-non-Gal xenoantibodies in vivo indicating that selective reduction of xenoantibodies can be accomplished without total B-cell depletion.

CONCLUSIONS

This preliminary study demonstrates the strength of approaches designed to selectively inhibit anti-non-Gal xenoantibody. Both anti-non-Gal-specific anti-idiotypic antibody and small molecules can be used to selectively limit xenoantibody responses.

Vaccine model of antiphospholipid syndrome induced by tetanus vaccine

Successful induction of antiphospholipid syndrome (APS) in two different non-autoimmune prone mouse strains, BALB/c and C57BL/6, was achieved by tetanus toxoid (TTd) hyperimmunization using different adjuvants (glycerol or aluminium hydroxide), and different adjuvant pretreatments (glycerol or Complete Freund’s Adjuvant (CFA)). APS had different manifestations of reproductive pathology in BALB/c and C57BL/6 mice: fetal resorption (as a consequence of extreme T-cell activation obtained in the course of pretreatment), and lowering of fecundity (as a consequence of polyclonal B-cell stimulation), respectively. In BALB/c mice fetal resorption coincided with glycerol and CFA pretreatments, while in C57BL/6 mice lowering of fecundity was most obvious in CFA-pretreated mice immunized with TTd in aluminium hydroxide. Both molecular mimicry and polyclonal B-cell activation occur in APS induction, with molecular mimicry effects being dominant in BALB/c mice, and polyclonal cell activation being dominant in C57BL/6 mice. Confirmation of molecular mimicry effects, which in the condition of T-cell stimulation generated fetal resorptions in the BALB/c strain, was achieved by passive infusion of monoclonal antibody (MoAb) T-26 specific for TTd and anti-β2-glycoprotein I obtained after TTd hyperimunization. High polyclonal B-cell activation in C57BL/6 mice prevented fetal resorption but induced fecundity lowering, as was the case in passive administration of MoAb T-26 in this mouse strain. Passive infusion of anti-idiotypic MoAb Y7 into C57BL/6 mice induced fetal resorptions and confirmed the above suggestion on the protective role of polyclonal B-cell stimulation in fetal resorptions.

Changes in pools of autoantibodies and anti-bacterial antibodies in patients suffering from recurrent infections of the urinary tract and undergoing bacterial immunization treatment

Antibodies (Abs) (IgM, IgA, IgG and IgG subclasses) specific for several uropathogenic strains (Escherichia coli, Pseudomonas sp. and Klebsiella sp.) as well as anti-phospholipids, anti-beta2-glycoprotein I and anti-laminin antibodies were analyzed in the sera of 20 patients with long-lasting uncomplicated recurrent infections of the lower urinary tract who underwent immunization treatment with a mixture of heat-inactivated bacteria. Immunization had a dual effect: a marked prolongation of the infection-free period in more than half of tested patients (which could be related to the profiles of anti-bacterial antibodies), and the induction of a significant decrease in autoreactivity. The results obtained showed that prolonged infections resulted in a significant rise in IgG specific for phospholipids, beta2-glycoprotein I and mouse laminin. However, irrespective of the effect on urinary tract infection per se, immunization induced a noticeable decrease in reactivity toward those antigens (Ag). The most abundant autoantibodies prior to immunization treatment were of IgG2 subclass. A statistically significant decrease in phospholipid specific antibodies belonging to this subclass, and in the concentration of Y7 cross-reactive idiotope, registered only in the responder group; this indicates the significance of natural antibody pool involvement in a proper anti-bacterial immune response.