Post-SARS-CoV-2 infection and post-vaccine-related neurological complications share clinical features and the same positivity to anti-ACE2 antibodies.

Introduction: A potential overlap in symptoms between post-acute COVID-19 syndrome and post-COVID-19 vaccination syndrome has been noted. We report a paired description of patients presenting with similar manifestations involving the central (CNS) or peripheral nervous system (PNS) following SARS-CoV-2 infection or vaccination, suggesting that both may have triggered similar immune-mediated neurological disorders in the presence of anti-idiotype antibodies directed against the ACE2 protein. Patients and methods: Four patients exhibited overlapping neurological manifestations following SARS-CoV-2 infection or vaccination: radiculitis, Guillain-Barré syndrome, and MRI-negative myelitis, respectively, sharing positivity for anti-ACE2 antibodies. Autoantibodies against AQP-4, MOG, GlyR, GAD, and amphiphysin, onconeural antibodies for CNS syndromes, and anti-ganglioside antibodies for PNS syndromes tested negative in all patients. Discussion: Anti-idiotype antibodies against ACE2 have been detected in patients who recovered from COVID-19 infection, and it has been hypothesized that such antibodies may mediate adverse events following SARS-CoV-2 infection or vaccination, resulting in the activation of the immune system against cells expressing ACE2, such as neurons. Our data reveal clinically overlapping syndromes triggered by SARS-CoV-2 infection or vaccination, sharing positivity for anti-ACE2 antibodies. Their presence, in the absence of other classic autoimmune markers of CNS or PNS involvement, suggests that they might play an active role in the context of an aberrant immune response. Conclusion: Anti-idiotype antibodies directed against ACE2 may be triggered by both SARS-CoV-2 infection and vaccination, possibly contributing to neurological autoimmune manifestations. Their pathogenic role, however, remains to be demonstrated in large-scale, more structured studies.

Belimumab concentration measurements using a homologous anti-idiotype immunoassay.

Monitoring belimumab concentrations in patients can be a valuable tool for assessing treatment response and for personalizing drug doses. Various assay formats may be used to measure concentrations of therapeutic monoclonal antibodies. A particularly useful format involves the use of anti-idiotype monoclonal antibodies, selected to be highly specific to the antibody of interest. Here, we describe the development of a specific, high-affinity anti-idiotype antibody to belimumab, and the application of this antibody in a homologous sandwich ELISA to measure belimumab concentrations.

The immunobiology of SARS-CoV-2 infection and vaccine responses: potential influences of cross-reactive memory responses and aging on efficacy and off-target effects.

Immune responses to both SARS-CoV-2 infection and its associated vaccines have been highly variable within the general population. The increasing evidence of long-lasting symptoms after resolution of infection, called post-acute sequelae of COVID-19 (PASC) or "Long COVID," suggests that immune-mediated mechanisms are at play. Closely related endemic common human coronaviruses (hCoV) can induce pre-existing and potentially cross-reactive immunity, which can then affect primary SARS-CoV-2 infection, as well as vaccination responses. The influence of pre-existing immunity from these hCoVs, as well as responses generated from original CoV2 strains or vaccines on the development of new high-affinity responses to CoV2 antigenic viral variants, needs to be better understood given the need for continuous vaccine adaptation and application in the population. Due in part to thymic involution, normal aging is associated with reduced naïve T cell compartments and impaired primary antigen responsiveness, resulting in a reliance on the pre-existing cross-reactive memory cell pool which may be of lower affinity, restricted in diversity, or of shorter duration. These effects can also be mediated by the presence of down-regulatory anti-idiotype responses which also increase in aging. Given the tremendous heterogeneity of clinical data, utilization of preclinical models offers the greatest ability to assess immune responses under a controlled setting. These models should now involve prior antigen/viral exposure combined with incorporation of modifying factors such as age on immune responses and effects. This will also allow for mechanistic dissection and understanding of the different immune pathways involved in both SARS-CoV-2 pathogen and potential vaccine responses over time and how pre-existing memory responses, including potential anti-idiotype responses, can affect efficacy as well as potential off-target effects in different tissues as well as modeling PASC.

Biased anti-idiotype response in rabbits leads to high-affinity monoclonal antibodies to biologics.

Antibody formation to human(ized) therapeutic antibodies in humans is highly skewed toward anti-idiotype responses, probably because the idiotype is the only 'foreign' part of the antibody molecule. Here, we analyzed antibody responses to F(ab')2 fragments of a panel of 17 human(ized) therapeutic antibodies in rabbits. Homology between the rabbit germline and the human(ized) antibodies is moderate not only for the variable domains (both the complementarity-determining regions and the framework regions), but also for the constant domains (66% or less). Nevertheless, we observed a highly skewed anti-idiotype response in all cases, with up to >90% of the antibodies directed toward the idiotype. These results indicate that the idiotype may be inherently immunodominant. We used these biased responses to raise monoclonal rabbit anti-idiotype antibodies against secukinumab, ustekinumab, reslizumab, mepolizumab, palivizumab, and dupilumab and demonstrate the potential to develop sensitive pharmacokinetic assays with these antibodies.

Toward a New Kind of Vaccine: A Logical Extension of the Symmetrical Immune Network Theory.

BACKGROUND: The symmetrical immune network theory, developed in 1975, is based on the existence of specific T cell factors and hypothesizes that normal IgG immune responses comprise the production of 2 kinds of antibodies, namely antigen-specific antibodies and anti-idiotypic antibodies. OBJECTIVE: The aim of this study was to confirm the existence of specific T cells factors and to show that immunization of C3H mice with BL/6 skin or using nominal antigen for immunization (Tetanus Toxoid) induced production of antigen-specific (anti-BL/6 or antitetanus) antibodies plus anti-idiotypic antibodies (C3H anti-anti-C3H). Subsequently, we investigated the role of combinations of antigen-specific and anti-idiotype antibodies in a variety of animal models of clinical diseases. METHODS: Antigen-specific antibodies were produced by conventional immunization of mice (eg, with tetanus toxoid or by skin allografting). Subsequent anti-idiotypic antibodies were derived by exhaustive absorption of antigen-specific antibody, with confirmation of anti-idiotypic specificity by binding to relevant target antigen-specific antibodies in an enzyme-linked immunosorbent assay (ELISA). Antigen-specific plus anti-idiotypic antibodies were then used to modulate skin allograft survival, dextran sulfate sodium (DSS)-induced colitis, ovalbumin (OVA)-induced IgE production, and breast cancer growth in mice. RESULTS: Infusions of anti-BL/6 antibodies together with BL/6 anti-anti-BL/6 antibodies specifically suppressed (>85%) an immune response to BL/6 lymphocytes in C3H mice. The two kinds of antibodies with complementary specificity are hypothesized to stimulate 2 populations of T lymphocytes. Coselection of these 2 populations leads to a new stable steady state of the system with diminished reactivity to BL/6 tissue. A combination of anti-C3H and C3H anti­anti-C3H IgG antibodies down-regulated inflammation in a mouse model of inflammatory bowel disease (>75%) and attenuated anti-IgE production and sensitization to produce IL4 cytokines (>70%) in an OVA-allergy model. Combination of C3H anti­BL/6 and BL/6 anti-anti-BL/6 antibodies decreased tumor growth and metastases (>705) in an EMT6 transplantable breast cancer model. CONCLUSIONS: Use of a combination of antigen-specific and anti-idiotypic antibodies has potential as a new class of vaccines.

Plant-Made Vaccines in the Fight Against Cancer.

Immunotherapies constitute an important trend in developing new cancer treatments, and several promising candidates are under evaluation in clinical trials. Plants have entered the fight against cancer because they constitute low-cost and efficient hosts for biopharmaceutical production that can also serve as oral delivery vehicles. This review is focused on the knowledge gained through the development of anticancer plant-made vaccines reported thus far, and highlights the potential of this technology - its success being reflected in the number of candidates that are close to market. Future prospects for anticancer plant-made vaccines are also identified.

Intravenous immunoglobulin: pharmacological properties and use in polyneuropathies.

INTRODUCTION: Intravenous immunoglobulin (IVIg) is increasingly used for the treatment of autoimmune and systemic inflammatory diseases with both licensed and off-label indications. The mechanism of action is complex and not fully understood, involving the neutralization of pathological antibodies, Fc receptor blockade, complement inhibition, immunoregulation of dendritic cells, B cells and T cells and the modulation of apoptosis. Areas covered: First, this review describes the pharmacological properties of IVIg, including the composition, mechanism of action, and adverse events. The second part gives an overview of some of the immune-mediated polyneuropathies, with special focus on the pathomechanism and clinical trials assessing the efficacy of IVIg. A literature search on PubMed was performed using the terms IVIg, IVIg preparations, side effects, mechanism of action, clinical trials, GBS, CIDP. Expert opinion: Challenges associated with IVIg therapy and the treatment possibilities for immune-mediated polyneuropathies are discussed. The availability of IVIg is limited, the expenses are high, and, in several diseases, a chronic therapy is necessary to maintain the immunomodulatory effect. The better understanding of the mechanism of action of IVIg could open the possibility of the development of disease-specific, targeted immune therapies.

Using monoclonal antibodies as an international standard for the measurement of anti-adalimumab antibodies.

Comparing studies investigating anti-drug antibody (ADA) formation is hampered by the lack of comparability between study protocols, assay formats, and standardized reference materials. In this respect, the use of an international standard would mean a major step forward. Here we compared 11 fully human monoclonal antibodies against adalimumab in two assays commonly used for ADA measurement; the bridging ELISA and the antigen binding test (ABT). Our results show non-parallel titration of the monoclonal antibodies in both assays, which we also find for polyclonal ADA sources. Moreover, we observed that the output of the bridging ELISA depends to a large degree on the affinity of the monoclonal antibody. For the ABT, results reflect a combination of affinity and avidity. This suggests that rather than reporting ADA values in nanogram per milliliter, arbitrary units may be more appropriate. Together our data highlight the difficulty of ADA standardization by identifying several pitfalls that should be taken into account when selecting a standard for ADA testing.

Anti-idiotype antibodies in immune regulation of anca associated vasculitis.

BACKGROUND: Anti-idiotype antibodies (anti-ids) have a potential role in the immunomodulation of various autoimmune disorders. The immunoregulatory role of anti-idiotypic antibodies in ANCA-associated vasculitis needs to be studied. This study was conducted in clinically and histopathologically diagnosed ANCA-associated vasculitis (AAV) patients. METHODS: Anti-ids were tested in 100 AAV patients of which 80 had anti-MPO and 20 had anti-PR3 antibodies at various stages of disease over a period of 2-3 years. The disease activity was estimated by the Birmingham vasculitis activity score (BVAS). The affinity-purified ANCA F(ab')2 fragments were prepared using three each of anti-MPO and anti-PR3 high titer sera and were used as idiotype coats for anti-idiotype antibody detection by ELISA. Positivity was confirmed by fluid phase inhibition ELISA. RESULTS: Patients who went into remission showed 53.8% anti-ids to anti-MPO and 52.9% to anti-PR3 with low BVAS values (0-8), whereas in patients with active disease, only 12.5% had anti-ids to anti-MPO and 10% had anti-ids to anti-PR3 with comparatively high BVAS (18-32), while five cases who had relapse (BVAS 18-20) did not have anti-ids to anti-MPO or anti-PR3. An inverse correlation was noted between ANCA and anti-ids (r = -0.901). CONCLUSIONS: High prevalence of anti-ids in remission cases and low prevalence in active cases with absence of anti-ids in relapse cases as well as an inverse correlation of ANCA and anti-ids indicate its beneficial effect on the disease process, thus suggesting the dynamic role of anti-idiotype networks in the immunoregulation of AAV.