Idiotype and anti-idiotype specific T cell responses on transplantation with hybridomas reactive to viral hemagglutinin and human tumor antigen

Biological mechanism and clinical effect of protein-bound polysaccharide K (KRESTIN(®)): review of development and future perspectives

The mechanism of action of protein-bound polysaccharide K (PSK; KRESTIN(®)) involves the following actions: (1) recovery from immunosuppression induced by humoral factors such as transforming growth factor (TGF)-β or as a result of surgery and chemotherapy; (2) activation of antitumor immune responses including maturation of dendritic cells, correction of Th1/Th2 imbalance, and promotion of interleukin-15 production by monocytes; and (3) enhancement of the antitumor effect of chemotherapy by induction of apoptosis and inhibition of metastasis through direct actions on tumor cells. The clinical effectiveness of PSK has been demonstrated for various cancers. In patients with gastric or colorectal cancer, combined use of PSK with postoperative adjuvant chemotherapy prolongs survival, and this effect has been confirmed in multiple meta-analyses. For small-cell lung carcinoma, PSK in conjunction with chemotherapy prolongs the remission period. In addition, PSK has been shown to be effective against various other cancers, reduce the adverse effects of chemotherapy, and improve quality of life. Future studies should examine the effects of PSK under different host immune conditions and tumor properties, elucidate the mechanism of action exhibited in each situation, and identify biomarkers.

Structural basis for the function of anti-idiotypic antibody in immune memory

We had earlier proposed a hypothesis to explain the mechanism of perpetuation of immunological memory based on the operation of idiotypic network in the complete absence of antigen. Experimental evidences were provided for memory maintenance through anti-idiotypic antibody (Ab(2)) carrying the internal image of the antigen. In the present work, we describe a structural basis for such memory perpetuation by molecular modeling and structural analysis studies. A three-dimensional model of Ab(2) was generated and the structure of the antigenic site on the hemagglutinin protein H of Rinderpest virus was modeled using the structural template of hemagglutinin protein of Measles virus. Our results show that a large portion of heavy chain containing the CDR regions of Ab(2) resembles the domain of the hemagglutinin housing the epitope regions. The similarity demonstrates that an internal image of the H antigen is formed in Ab(2), which provides a structural basis for functional mimicry demonstrated earlier. This work brings out the importance of the structural similarity between a domain of hemagglutinin protein to that of its corresponding Ab(2). It provides evidence that Ab(2) is indeed capable of functioning as surrogate antigen and provides support to earlier proposed relay hypothesis which has provided a mechanism for the maintenance of immunological memory.

Immunization of mice with DNA coding for the variable regions of anti-idiotypic antibody generates antigen-specific response

Understanding the mechanisms of generation and maintenance of immunological memory is crucial for rational vaccine design. A hypothesis known as relay hypothesis was earlier proposed which explains the maintenance of immunological memory through interaction of idiotypic and anti-idiotypic lymphocytes. In the present study, we have shown that immunization with rinderpest virus hemagglutinin protein specific anti-idiotypic antibody (Ab(2)v(beta)) DNAs coding for heavy and light chains generates antigen-specific antibody and T cell responses as well as Ab1 specific T cell response. We further show that boosting with the recombinant Ab(2)-vbeta proteins generates B and T cell memory response specific for antigen in anti-id DNA primed mice. This study provides experimental evidence for perpetuation of immunological memory through idiotypic network interactions.

Maintenance of antigen-specific immunological memory through variable regions of heavy and light chains of anti-idiotypic antibody

Immunological memory is characterized by a quick and enhanced immune response after re-exposure to the same antigen. To explain the mechanism involved in generation and maintenance of immunological memory, we had earlier proposed a hypothesis involving the relay of memory by idiotypic and anti-idiotypic B cells. The peptidomimic present in the hypervariable region of anti-idiotypic antibody was hypothesized to carry forward immunological memory. In the present work, we provide evidence supporting a role for the anti-idiotypic antibody in eliciting antigen-specific B-cell and T-cell responses. Employing the idiotypic monoclonal antibody (Ab(1)) specific for haemagglutinin (H) protein of rinderpest virus, Ab(2beta) was generated, which possesses an internal image of the H protein in the region between amino acids 527 and 556. We demonstrate that antigen-specific memory is perpetuated by immunization with Ab(2), as shown by maintenance of antigen-specific T-cell responses upon restimulation in vitro of Ab(2) immune splenocytes by antigen-presenting cells expressing H protein or pulsed with H-protein-derived peptides. We have also shown that boosting with antigen-specific anti-idiotypic B cells generates a memory response in antigen-primed mice. Evidence has been provided for the existence of an antigen-specific B-cell idiotypic network in the body that supports the perpetuation of immunological memory as proposed in the relay hypothesis.

Activated mouse T cells downregulate, process and present their surface TCR to cognate anti-idiotypic CD4+ T cells

The ability of activated T cells to present foreign antigens through the MHC class II pathway has been shown in the case of human, rat and mouse T cells. In the present study, the ability of activated T cells to present their endogenous TCR in association with MHC class II molecules to CD4+ T cells was shown. Upon activation mouse T cells downregulate their surface TCR, which are degraded into peptides in endosomal/lysosomal compartments. The idiopeptides (peptides derived from the variable region of the TCR) are presented to cognate anti-idiotypic CD4+ T cells, resulting in activation and proliferation of these cells. Interaction of idiotypic and anti-idiotypic T cells brought about by presentation of TCR idiopeptide may have important implications for T-cell vaccination and perpetuation of T-cell memory not requiring persisting antigen or long-lived memory cells.

Recombinant idiotypic TCRβ chain immunization in mice generates antigen specific T cell response

Vaccination remains the most cost-effective means of preventing infectious diseases. Success of vaccination depends on generation of effective memory response. Understanding the mechanism of generation and maintenance of immunological memory would help in the design of rational vaccines. T lymphocytes play a central role in the generation of protective immune response against many microbial infections. A hypothesis known as relay hypothesis was earlier proposed, which explains the maintenance of immunological memory through interaction of idiotypic and anti-idiotypic lymphocytes. In the present study, we have shown that immunization with a model antigen, chicken ovalbumin specific T cell receptor beta chain (idiotypic TCR) generates TCR specific antibody and anti-idiotypic T cell responses as well as ovalbumin specific T cell response. We further show that boosting of ovalbumin primed mice with ovalbumin specific idiotypic TCRbeta DNA or TCRbeta protein gives memory response for ovalbumin. This study provides experimental evidence for perpetuation of immunological memory through idiotypic network interactions.

Autoantigen complementarity: a new theory implicating complementary proteins as initiators of autoimmune disease

Autoimmune diseases affect approximately 1 in 21 persons in the United States. Treatment often requires long-term cytotoxic therapy. How and why these deleterious diseases occur is unclear. A serendipitous finding in our laboratory using serum from patients with autoimmune vasculitis led us to develop the theory of autoantigen complementarity, a novel concept that may elucidate the etiological and pathogenetic mechanisms underlying autoimmune disease in general. The theory proposes that the inciting immunogen that elicits a cascade of immunological events is not the self-antigen (the autoantigen) or its mimic but rather a protein that is complementary in surface structure to the autoantigen; that is, a protein homologous or identical to the amino acid sequence of translated antisense RNA from the noncoding strand of the autoantigen gene. The cascade begins when this complementary protein initiates the production of antibodies that in turn elicit an anti-antibody or anti-idiotypic response. These anti-idiotypic antibodies can now react with the autoantigen. Strikingly, homology search of complementary proteins yields microbial and fungal proteins, thus indicating that invading micro-organisms can deliver the inciting immunogen. Curiously, approximately 50% of our patients transcribe the complementary protein's antisense RNA. If it transpires that these aberrant RNAs are translated, the complementary protein would be produced by the individual. Here we review published research investigating complementary proteins, anti-idiotypic immune responses, and antisense transcripts, all of which support complementary proteins as initiators of autoimmune disease. In addition, we provide possible microbial and/or fungal organisms that may incite some of the most studied autoimmune diseases. Lastly, we propose mechanisms by which cell-mediated autoimmunity can be triggered by autoantigen complementarity. Based on our data and the contributions of the researchers described in this review, identification of proteins complementary to autoantigens is likely to be informative in most autoimmune diseases. This vein of study is in the early phases; however, we expect "autoantigen complementarity" is an underlying mechanism in many autoimmune diseases.