Secondary Ab Responses Research Articles

Coexpression of B7-1 and antigen blocks tolerance induction to antigen presented by resting B cells.

To investigate a role for B cells as tolerogenic APCs in peripheral lymphoid organs, we have developed a system in which B cells from mice transgenic for the membrane-bound form of human mu-chain are transferred into nontransgenic recipients. Mice injected with B cells expressing human mu-chain became profoundly tolerant to human mu-chain, as shown by greatly reduced Ab responses following challenge with human mu-chain in adjuvant. Adoptive transfer experiments showed that the recipient's Th cell response to human mu-chain was impaired. When the human mu transgenic spleen cells were activated with LPS before transfer, they no longer induced tolerance. Spleen cells from double-transgenic mice expressing both human mu-chain and the costimulatory molecule B7-1 (CD80) also failed to induce tolerance to human mu-chain. However, neither human mu transgenic LPS blasts nor double-transgenic B cells induced an Ab response or primed for a secondary Ab response to Ag in adjuvant. Therefore, we find that expression of B7-1 together with Ag can interfere with tolerance induction without inducing Ab formation or priming for a secondary Ab response.

Induction of autoantibody responses to GM-CSF by hyperimmunization with an Id-GM-CSF fusion protein.

Fusion proteins consisting of an Ig containing xenogenic constant regions and granulocyte-macrophage colony stimulating factor (Id-GM-CSF) are potent immunogens capable of inducing anti-idiotypic Abs after two immunizations, without the usual need for adjuvants or carrier proteins. In this study, we investigated the effects of hyperimmunization with Id-GM-CSF and found that it induces anti-GM-CSF Abs that could bind to GM-CSF and neutralize its bioactivity in vitro. However, no detrimental effects of the anti-GM-CSF activity were apparent on the general health of the animals or on their base line white blood cell counts. Mice with the anti-GM-CSF activity reconstituted their peripheral white blood cells with identical kinetics as control mice after high dose cyclophosphamide treatment, sublethal irradiation, or lethal irradiation followed by syngeneic bone marrow transplantation. Primary and secondary Ab responses to a variety of protein Ags, including an unrelated Ig Id, were not affected. However, the anti-Id response induced by an unrelated GM-CSF fusion protein that is dependent upon the GM-CSF bioactivity was impaired. To avoid any potential problems associated with inducing anti-GM-CSF Abs, we show that priming with the Id-GM-CSF protein and boosting with the Id protein alone were sufficient to induce comparable anti-Id titers without inducing anti-GM-CSF Abs. We conclude that although hyperimmunization of mice with the GM-CSF fusion protein induced neutralizing anti-GM-CSF Abs, this was of little consequence to the animals. Nevertheless, we have devised a strategy to overcome this potential limitation on the use of GM-CSF fusion proteins for immunization.

Oligomeric IgD augments and monomeric IgD inhibits the generation of IgG memory antibody responses in normal, but not in IgD-deficient, mice.

Dimeric or aggregated IgD causes augmentation of primary and secondary Ab responses in mice when injected a few days before or together with the primary dose of Ag. This effect is mediated by Th cells and seems to be linked to the up-regulation of receptors for IgD on CD4+ T cells. IgD-R cross-linking is needed for receptor up-regulation. Here we show that addition of monomeric IgD to dimeric or aggregated IgD blocks IgD-R up-regulation on T cells in vitro and in vivo, as well as their immunoaugmenting effect in vivo. More importantly, monomeric IgD injected 6 to 24 h before a primary Ag injection also inhibits 1) the up-regulation of IgD-R on T cells induced by Ag injection alone, and 2) the generation of IgG memory, as shown in the response to a second dose of Ag injected on day 10. These results suggest that IgD-R on T cells contribute to the T-B cell interaction involved in the priming for a secondary response. The augmenting effect of oligomeric IgD and the inhibiting effect of monomeric IgD on secondary Ab responses are not observed in IgD-/- (IgD-deficient) mice, although injection of oligomeric IgD leads to IgD-R up-regulation on T cells in these mice. These results indicate that IgD presented in the form of immune complexes, most likely on the surface of B cells, is a prerequisite for the immunoaugmenting effects exerted by IgD-R+ T cells. Thus, IgD is the only physiologic ligand for IgD-R on T cells.

Escherichia coli heat-labile enterotoxin B subunits supplemented with a trace amount of the holotoxin as an adjuvant for nasal influenza vaccine.

Escherichia coli heat-labile enterotoxin B subunit (LTB) (2 micrograms), supplemented with a trace amount of the holotoxin (LT) (0.02-20 ng), was examined for the adjuvant effect on antibody (Ab) responses against influenza inactivated haemagglutinin (HA) vaccine in Balb/c mice. Each mouse received a primary intranasal (i.n.) inoculation with the vaccine (1.5 micrograms), prepared from PR8 (H1N1) virus, together with LT-containing LTB and in 4 weeks a second i.n. inoculation of the vaccine alone. The inoculation of the vaccine with the LT-containing LTB induced significantly high primary and secondary anti-HA IgA and IgG Ab responses in the nasal wash and the serum, while the vaccine with LTB or less than 2 ng of LT induced little response. The synergistic adjuvant effect was maximal in the concentration of LTB supplemented with 0.2-2 ng of LT. Under these conditions, the augmented IgA and IgG Ab responses, which are cross-protective to PR8 HA molecules, provided complete cross-protection against PR8 virus challenge in mice immunized with heterologous vaccine within the same subtype. These results suggest that LTB containing a trace amount of LT can be used as a potent adjuvant for nasal vaccination of humans against influenza.

Antibody responses to protein, polysaccharide, and ΦX174 antigens in the hyperimmunoglobulinemia E (hyper-IgE) syndrome

To investigate whether an underlying defect in antibody (Ab)-forming capacity could contribute to the infection susceptibility of patients with hyper-IgE syndrome, we evaluated 11 such patients for their responses to bacteriophage ΦX174 (ΦX174), diphtheria and tetanus toxoids, and pneumococcal (Pneumovax) and Hemophilias influenzae vaccines. Three of nine patients immunized with ΦX174 had normal primary and secondary Ab responses, five had accelerated declines in their titers after initially normal primary Ab responses and lower than normal secondary Ab responses, and two of the latter patients failed to switch normally from IgM to IgG Ab production. Only one of 10 patients tested had normal Ab responses to diphtheria toxoid, and postimmunization antitetanus titers were abnormally low in five of the 10 patients tested. Serum Abs to H. influenzae polyribose phosphate were protective in seven of the eight immunized patients. Five of the nine patients administered Pneumovax had poor Ab responses to at least one of the pneumococcal serotypes 7, 9, or 14. Abnormal antipolysaccharide responses did not correlate with IgG 2 deficiency. All patients responded with protective Ab levels to type 3. Thus, patients with hyper-IgE syndrome are heterogeneous with respect to their Ab-forming capacities. Ab deficiency may contribute to infection susceptibility in some of these patients.

Humoral response and memory formation in carp after injection of [formula omitted][formula omitted] bacterin

The humoral immune response of carp ( Cyprinus carpio ) upon a bacterial fish pathogen Aeromonas hydrophila was studied in relation to memory formation. After a single intramuscular (i.m.) injection of formalin killed A. hydrophila cells (F-Ah), maximum serum Ab (Ab) titers were observed at day 20. Distinct titers were still seen at day 360 in the groups injected with a medium or high antigen (Ag) dose (10 7 respectively 10 9 F-Ah). The effect of a second immunization with a high Ag dose was studied in fish primed 1, 3, 8 or 12 months earlier with 10 5, 10 7 or 10 9 F-Ah. The height of the secondary Ab response was positively correlated with the height of the priming Ag dose. Challenge with a low Ag dose (10 6 F-Ah) gave the best results with 10 7 F-Ah primed animals. The highest secondary responses were obtained with combinations of corresponding priming and challenge dosages. It is concluded that fish are able to form immunological memory to this bacterial Ag. However, optimal memory levels are reached after a relative long period (3 – 8 months).

Immunogens consisting of oligosaccharides from the capsule of Haemophilus influenzae type b coupled to diphtheria toxoid or the toxin protein CRM197.

Haemophilus influenzae type b (Hib) capsular polysaccharide (PRP) was selectively hydrolyzed to reducing oligosaccharides, and the fraction containing 3-10 ribosylribitolphosphate repeating units (VS) was conjugated by reductive amination to diphtheria toxin (DTx), its nontoxic derivative CRM197 (Dcr), or diphtheria toxoid (DTd). Conjugate DTx-VS retained approximately 1% of native toxicity, which was eliminated by treatment with formalin. Immunization of rabbits with the conjugates elicited antibody (Ab) to PRP and to DTx but not to a model for the linkage determinant. Human adults given single subcutaneous injections had rises in serum Ab to PRP and in bactericidal activity in vitro; the Ab protected infant rats challenged with Hib. Adults had rises also in Ab to DTd, and these Ab protected rabbits against DTx. A series of two injections of the conjugates Dcr-VS and DTd-VS was tested in infants beginning at 19-23 mo of age. Rises in anti-PRP Ab after the primary resembled the rises after PRP vaccine. In contrast to PRP, the conjugates elicited large rises after the secondary vaccinations and a substantial IgG component. Development of bactericidal activity paralleled the rises in anti-PRP Ab. Secondary rises after Dcr-VS were higher than after DTd-VS. In infants 12-16 mo of age, Dcr-VS (but not DTd-VS) elicited strong primary and secondary Ab responses that included IgG and bactericidal activity. Both conjugates produced consistent rises in Ab to DTd.

The reaction of the immune system of fish to vaccination: development of immunological memory in carp, Cyprinus carpio L., following direct immersion in Aeromonas hydrophila bacterin

Abstract. The development of immunological memory was investigated in carp following direct immersion in Aeromonas hydrophila bacterin. A single bath did not induce an increase in serum antibody (Ab) levels. A second bath at 1, 3 or 8 months resulted in clear secondary Ab responses. The highest Ab levels were reached in the group boosted after 3 months. However, at 12 months a second bath gave no further significant response. When a booster was given at the same intervals by intramuscular injection, instead of immersion, the induced memory was not expressed as a clear secondary response. It is concluded that direct immersion in a bacterial antigen did induce immunological memory. The duration of this slowly developing memory is limited in time (less than 12 months) and was only demonstrated following a second immersion. This last feature suggests the existence of a local or mucosal activity during the immune response after bath vaccination.

Idiotype profile of an immune response. II. Reversal of the relative dominance of major and minor cross-reactive idiotypes in arsonate-specific T-independent responses.

Two different cross-reactive idiotype (CRI) groups are distinguishable in the Ab response of A/J mice to the p-azobenzenearsonate (ABA) hapten: CRIA and CRIm. These two groups showed distinct patterns of relative dominance in the ensuing response depending on whether the inducing Ag was a T cell-dependent (TD) form of ABA, such as ABA-KLH or ABA-CGG, or a T-independent type 1 (TI-1) form, such as ABA-Brucella abortus or ABA-lipopolysaccharide (LPS), and on whether the response was elicited in vivo or in vitro. The CRI+ component of primary in vivo plaque-forming cell (PFC) responses to TD ABA Ags was largely (greater than 90%) CRIA+ as was, to a slightly lesser extent (greater than 75%) the CRI+ portion of secondary or hyperimmune serum Ab or PFC responses to the same Ags. In contrast, in vivo primary and hyperimmune PFC responses to ABA-Bru or ABA-LPS showed a significantly lower CRIA/CRI ratio, averaging 0.5-0.6, with some individual mice giving figures as low as 0.2, indicating predominance of CRIm over CRIA. Serological analysis of hyperimmune anti-ABA Abs from a group of 5 A/J mice immunized with ABA-Bru gave a figure of less than 0.5 for the CRIA/CRI ratio. The most striking disparity from the TD pattern was seen in primary in vitro PFC responses to the TI ABA Ags; here ratios of less than 0.2 were generally seen. Since T cell removal did not alter the Id pattern in the TI responses, CRIA-specific Ts cells do not account for the weak expression of CRIA in such responses. We propose a model that explains these results on the basis of differential expression of IdX dominance by two distinct B cell subpopulations--equatable to the Lyb-5+ and Lyb-5- B cell subsets--along with differential relative activation of these subsets in different types of responses. Examination of anti-ABA PFC responses of F1 progeny of CBA/N and A/J mice to ABA-Bru lends support to this hypothesis since CRIA expression was significantly lower in mice with the xid defect.