Lack of involvement of auto-anti-idiotypic antibody in the regulation of oscillations and tolerance in the antibody response to levan

T-Independent IgA Responses to Microbial Polysaccharides

There is accumulating evidence indicating the presence in vivo of T-independent routes of IgA response in addition to the conventional T-dependent IgA response. Factors influencing these alternative pathways of IgA responses may include the structural characteristics of a stimulating antigen, the nature of responding B cells, and the microenvironment. The structural complexity of polysaccharide antigens has made it difficult to summarize a general scheme for the antibody responses they induce. Instead, one may expect that each individual polysaccharide may be able to create a unique microenvironment by activation of specific cell populations in the repertoires of non-T cell types. A specific pattern of B cell response may thus be elicited by TI stimulation. Recognition of such a unique property of a TI antigens is necessary for us to better understand the T-independent IgA response. Information obtained may have an impact on the development of vaccination strategies directed at the mucosal immunity mediated by IgA antibodies.

Detection of autologous antiidiotypic antibody-forming cells by a modified enzyme-linked immunospot (ELISPOT)

We describe here the utilization of a modified enzyme-linked immunospot assay (ELISPOT) in order to detect an autologous antiidiotypic response in mice at the level of single antibody-forming cells (AFC). Severals assays have been routinely used to detect anti-Id producing cells; however, these approaches often produce contrasting data. We present results obtained with the modified ELISPOT, using as a model system the antiidiotypic response in mice after immunization with a vaccine from Streptococcus pneumoniae R36a, expressing the immunodominant epitope phosphorylcholine (PC). The response to PC is mediated by a large fraction of antibodies bearing the public idiotype T15. Mice of different genetics make up were immunized with a single injection of the vaccine. We observed that one mouse strain (D1.LP) out of three was able to mount a significant anti-T15 response during the primary anti-phosphorylcholine response. BALB/c and C57BL/6 mice did not produce significant levels of anti-T15 antibody following a single injection of the antigen. In contrast, BALB/c mice which were repeatedly stimulated showed a specific anti-Id response. Experimental controls were performed using either specific anti-T15 monoclonal antibodies (mAb) or splenocytes from mice immunized with TEPC15 myeloma protein in complete Freund's adjuvant.

Behavior of the idiotypic network in conventional immune responses. I. Kinetics of idiotypic and anti-idiotypic antibodies following immunization with T-independent and T-dependent antigens

A minimal requirement in investigations of the behavior of the idiotypic network during immunization is the ability to quantitate both the idiotypic (Ab1) and anti-idiotypic (Ab2) responses. Quantitation of Ab2 in serum is complicated by the simultaneous presence of Ab1, so that Ab1-Ab2 immune complexes escape detection. In contrast, immune complexes should not complicate the enumeration of Ab2-producing lymphocytes in a hemolytic plaque assay. This study utilizes a procedure that allows detection of Ab2-producing cells in such an assay. The procedure relies upon the insertion of the appropriate antibody (Ab1) into the membrane of indicator SRBC through a covalently attached dipalmitoyl phosphatidylethanolamine (DPPE) tail. When the Ab2 response following murine immunization with DNP-Ficoll was analyzed using such an assay, peak plaque-forming cell (PFC) numbers were found to coincide with peak Ab1 PFC numbers in both the primary and secondary response. In addition, this Ab2 response was found to be T independent. The murine immune response to DNP-HGG demonstrated a peak Ab2 PFC response which followed the peak Ab1 PFC response after both primary and secondary immunization. This Ab2 response appeared to be T dependent. The secondary responses to both DNP-Ficoll and DNP-HGG showed increased levels of Ab2 PFC and decreased levels of Ab1 PFC in comparison to the primary responses to the same antigens, suggesting that immunoregulation may occur within these idiotypic networks.

A study of autologous anti-idiotypic antibody-forming cells in mice of different ages and genetic backgrounds

Antibody response to phosphorylcholine, an immunodominant epitope of Streptococcus pneumoniae R36a (Pn), is characterized by a public idiotype, T15, that is expressed on a large proportion of antibody molecules produced by all mouse inbred strains. The ability of the immune system to produce an autologous antibody to T15 upon immunization with Pn vaccine was investigated using a modified ELISA plaque assay for detection of single antibody-forming cells (AFC). The limit of ELISA assay for detection of specific anti-T15 AFC is approximately 300 cells/spleen. However, our studies failed to detect any autologous anti-T15 AFC in the course of the primary antibody response to Pn vaccine in young/adult (2-4 months) BALB/c and C57BL/6 mice. Aged mice (20-22 months) also failed to develop any specific auto-anti-T15 AFC upon the primary Pn immunization, despite the fact that the anti-Pn response in these animals changes both quantitatively and qualitatively. In order to generate specific anti-T15 AFC, BALB/c mice had to be immunized repeatedly with Pn vaccine (four weekly injections) or immunized directly with T15 protein in CFA. Different results were obtained with D1.LP mice that are low responders to Pn and express lower levels of T15 Id as compared to BALB/c. Young D1.LP mice produced high numbers of auto-anti-T15 AFC of both IgM and IgG isotypes following a single immunization with Pn vaccine. The kinetics of auto-anti-T15 response in D1.LP mice was similar to that of the antigen-specific response. These results demonstrate that the ability of the immune network to produce autologous antibody to a shared Id depends on the genetic makeup of the host, and that this response may be regulated by the level of Id expression.

Characterization of the immunodeficiency of RIIIS/J mice: immune response to polysaccharide antigens

RIIIS/J mice lack an autosomal dominant gene(s) that influences the magnitude of the antibody response to several polysaccharide antigens of bacterial origin. Low responsiveness is demonstrable whether polysaccharide is administered as a T-helper-cell-independent or -dependent antigen conjugated to an immunogenic carrier; however, RIIIS/J mice make good anti-hapten antibody responses to haptenated polysaccharides. The low antibody responses of RIIIS/J mice to type III pneumococcal polysaccharide do not appear to be the results of an imbalance in the activity of regulatory T lymphocytes. Compared with other strains of mice, RIIIS/J mice elicit low antibody responses to lipopolysaccharide (LPS). They do not develop a cyclic primary or secondary antibody response to Escherichia coli O113 LPS; the latter is not due to a lack of mitogenic response to E. coli O113 LPS. They also produce auto-anti-idiotypic antibody after being immunized with trinitrophenyl-Ficoll.

The immune response to pneumococcal polysaccharide type III is followed by increased production of an antibody antifactor

The study shows that serum from pneumococcal polysaccharide type III (SSSIII)-immunized and nonimmunized mice that has been absorbed until devoid of anti-SSSIII antibodies inhibits anti-SSSIII plaque-forming cells (PFC) but not antisheep red blood PFC in antibody plaque assay. A large fraction of the inhibitions activity can be absorbed by and eluted from anti-SSSIII-Sepharose, but not normal mouse serum-Sepharose. It has low or no affinity for protein A and concanavalin A. The titre of the inhibitor increases with repeated immunizations and inhibits the anti-SSSIII PFC of rats or mice of different allotypes. On the basis of these characteristics, I classify the inhibitor as an anti-idiotypic nonimmunoglobulin factor directed against a common determinant of anti-SSSIII antibodies of mouse and rat, with an immuno-regulatory function.