Bovine γ-globulin, lactoferrin, and lactoperoxidase are relevant bovine milk allergens in patients with α-Gal syndrome.

BACKGROUND: Mammalian meat is the most common trigger of the allergic reactions in patients with α-Gal syndrome (AGS). Milk and dairy, although less often, also cause a significant number of allergic manifestations. The aim of this study was to identify α-Gal-containing bovine milk proteins with allergenic properties among AGS patients. METHODS: Thirty-eight AGS patients with IgE to milk were included in the study. Milk proteins were analyzed for the presence of α-Gal and for binding by patients' IgE using immunoblot, ImmunoCAP, and inhibition ELISA. Allergenicity of milk and milk proteins was assessed by basophil activation test. RESULTS: More than half of the AGS patients reported allergic reactions to milk or dairy products. Bovine γ-globulin (BGG), lactoferrin (LF), and lactoperoxidase (LPO) were identified as α-Gal carrying proteins which were recognized by AGS patients' IgE. Whey mirrored the anti-α-Gal and IgE reactivity of BGG, LF, and LPO. Eighty-nine percent of the patients displayed IgE to BGG, 91% to LF, and 57% to LPO. Inhibition of α-Gal-specific IgE binding was achieved by BGG, LF, LPO, and whey. These proteins also activated AGS patients' basophils. Interestingly, at lower concentrations, LF was the most potent inhibitor of IgE binding, and the most potent activator of basophils. CONCLUSION: BGG, LF, and LPO were all found to be relevant milk α-Gal-containing glycoproteins that bound AGS patients' IgE antibodies and activated their basophils. These proteins are probably involved in the allergic reactions to milk in AGS patients. LPO was for the first time shown to be an allergen.

Two patients with rituximab associated low gammaglobulin levels and relapsed covid-19 infections treated with convalescent plasma.

Patients with haematological malignancies are considered to be a risk group for developing severe Coronavirus disease (Covid-19). Because of the limitations of therapeutic options, the development of new treatment strategies is mandatory, such as convalescent plasma (CP). Herein we report the use of CP therapy as an off-label indication in two lymphoma patients with relapsed COVID-19 in the setting of low gammaglobulin levels because of previous rituximab chemo-immunotherapy. Both were PCR positive for SARS-CoV-2 but had an absence of antibodies to the virus more than one month later of symptoms initiation. They developed important respiratory and neurological complications. After CP infusion, neutralising antibodies were detected and viral load dissapeared in both patients leading to clinical improvement with no more Covid-19 relapse.

Effect of Anti-Glutamate Antibodies in Modeled Parkinsonian Syndrome.

We studied the effect of single and repeated intranasal administration of antibodies to glutamate in experimental parkinsonian syndrome induced by injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to C57BL/6J mice. Intranasal administration of anti-glutamate antibodies to mice in parallel with administration of MPTP over 10 days alleviated parkinsonian symptoms (oligokinesia and rigidity). In the serum of mice injected with antibodies to glutamate and/or MPTP, the titers of autoantibodies to glutamate and dopamine were higher than in control animals receiving saline. Single intranasal administration of anti-glutamate antibodies to mice with established parkinsonian syndrome did not affect the severity of parkinsonian symptoms.

Abatacept induced long-term non-progressive reduction in gamma-globulins and autoantibodies: dissociation from disease activity control.

OBJECTIVES: To evaluate long-term effects on gamma-globulins and autoantibodies of abatacept (ABA) versus tumor necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA) patients. METHOD: Eighteen RA patients undergoing abatacept (ABA-RA) and 18 age/sex-matched patients treated with TNFi (TNFi-RA) were compared regarding clinical data, total gamma-globulins (TGG), specific subtypes (IgG, IgM, IgA), free light chains (FLC), IgM/IgG rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP3), and anti-mutated citrullinated vimentin (anti-MCV), assessed before and every 6 months, up to 24 months. EXCLUSION CRITERIA: previous abatacept/rituximab or low TGG (< 0.7 g/dL). RESULTS: At baseline, female sex (78 vs. 78%), age (55 vs. 53 years), DAS28 (5.73 vs. 5.67), TGG (1.4 vs. 1.35 g/dL), IgG (1168 vs. 1079 mg/dL), IgM (107 vs. 113 mg/dL), IgA (333 vs. 322 mg/dL), kappa (342 vs. 249 mg/dL), lambda (170 vs. 150 mg/dL), IgM-RF (76 vs. 53 UI), IgG-RF (63 vs. 25 UI), anti-CCP3 (216 vs. 189 UI), and anti-MCV (202 vs. 102 UI) were comparable in ABA-RA and TNFi-RA (p > 0.05). Similar disease activity improvement was observed in both groups. In ABA-RA, significant decreases (p < 0.05) were observed in TGG (1.4 vs. 1.05 g/dL), IgG (1168 vs. 997), IgA (333 vs. 278 mg/dL), kappa (342 vs. 257 mg/dL), lambda (170 vs. 144 mg/dL), IgM-RF (76 vs. 37 UI), IgG-RF (65 vs. 24 UI), anti-CCP3 (216 vs. 183 UI), and anti-MCV (202 vs. 60 UI) at 6 months, without further decreases. In contrast, TNFi-RA showed no decrease in any of such parameters. ABA-RA also had more often transient IgG levels under the lower limit of normality (66.7% vs. 33.3%, p = 0.046). No severe infection occurred. DAS28, ESR, and CRP correlated significantly to gamma-globulins and FLC at baseline (p < 0.05), but these correlations were longitudinally lost in ABA-RA, but not in TNFi-RA. CONCLUSION: ABA, but not TNFi, induces a safe, persistent, long-term, and non-progressive reduction in gamma-globulins and autoantibodies, including anti-MCV. This pattern is dissociated from disease activity control.Key Points• ABA induces a long-term and non-progressive reduction in gamma-globulins and FLC, which occurs regardless of disease activity control.• ABA-induced reduction in gamma-globulins and FLC promotes a dissociation of such parameters and disease activity.• The same pattern of reduction is observed in autoantibodies: IgM-RF, IgG-RF, anti-CCP3, and anti-MCV.• Low transient IgG can be observed in RA patients treated with ABA, but does not correlate to infection.

Selective depletion of plasma cells in vivo based on the specificity of their secreted antibodies.

Antibody-mediated diseases affect more than 10% of the human population. For most, no cure is available, particularly when the pathogenic antibodies are secreted by long-lived plasma cells resistant to conventional immunosuppressive therapies. Current therapeutic approaches target not only the plasma cells that secrete pathogenic antibodies, but also those providing protective antibodies. Here, in a murine model bearing long-lived plasma cells secreting anti-OVA and -chicken gamma globulin (CGG) antibodies, we describe the first-time use of an antigen-antibody (OVA/anti-CD138 antibody) conjugate for in vivo labeling and selective ablation of plasma cells that secrete antibodies specific for the antigen OVA. The selective depletion also led to a stable reduction of the corresponding serum anti-OVA antibody levels. In contrast, CGG-specific plasma cells and circulating anti-CGG antibody levels remained unchanged. The method described here should enable the development of unique causative treatment strategies for established antibody-mediated diseases sparing humoral immunity.

Immune Complexes Impaired Glomerular Endothelial Cell Functions in Lupus Nephritis.

Lupus nephritis (LN) is one of the most common and severe complications of lupus. However, the mechanisms for renal damage have not been well elucidated. There are evidences show that glomerular endothelial cells (GECs) are damaged in LN. Immune complexes can deposit in subendothelial area and could affect GEC functions. In the present study, we used heat-aggregated gamma globulin (HAGG) to simulate immune complexes and investigated their effects on GEC functions. Our results revealed that HAGG impaired different aspect of the GEC functions. HAGG changed cell morphology, upregulated the expression of active caspase-3, inhibited angiogenesis, and increased NO production in GECs. These results provide new clues for the mechanisms of renal damage and the pathology of LN.

Antigen Complexed with a TLR9 Agonist Bolsters c-Myc and mTORC1 Activity in Germinal Center B Lymphocytes.

The germinal center (GC) is the anatomical site where humoral immunity evolves. B cells undergo cycles of proliferation and selection to produce high-affinity Abs against Ag. Direct linkage of a TLR9 agonist (CpG) to a T-dependent Ag increases the number of GC B cells. We used a T-dependent Ag complexed with CpG and a genetic model for ablating the TLR9 signaling adaptor molecule MyD88 specifically in B cells (B-MyD88- mice) together with transcriptomics to determine how this innate pathway positively regulates the GC. GC B cells from complex Ag-immunized B-MyD88- mice were defective in inducing gene expression signatures downstream of c-Myc and mTORC1. In agreement with the latter gene signature, ribosomal protein S6 phosphorylation was increased in GC B cells from wild-type mice compared with B-MyD88- mice. However, GC B cell expression of a c-Myc protein reporter was enhanced by CpG attached to Ag in both wild-type and B-MyD88- mice, indicating a B cell-extrinsic effect on c-Myc protein expression combined with a B cell-intrinsic enhancement of gene expression downstream of c-Myc. Both mTORC1 activity and c-Myc are directly induced by T cell help, indicating that TLR9 signaling in GC B cells either enhances their access to T cell help or directly influences these pathways to further enhance the effect of T cell help. Taken together, these findings indicate that TLR9 signaling in the GC could provide a surrogate prosurvival stimulus, "TLR help," thus lowering the threshold for selection and increasing the magnitude of the GC response.

Hirudin ameliorates immunoglobulin A nephropathy by inhibition of fibrosis and inflammatory response.

Immunoglobulin A nephropathy (IgAN) is characterized by mesangial IgA and IgG co-deposition. As the clinical course of IgAN is highly variable, a lot of patients will eventually develop to end-stage renal disease (ESRD) within years. Hirudin, a potent and specific thrombin inhibitor, has been reported to treat IgAN with hematuria, but the mechanism is unclear. Our study aims to explore the potential of hirudin and the underlying mechanism in the treatment of IgAN. The establishment of IgAN model was set up in rats through oral and intravenous immunization with bovine gamma-globulin (BGG). Results suggested that hirudin could reduce the increased level of proteinuria, serum creatinine and urea nitrogen in IgAN models. Besides that, hirudin ameliorated the elevated number of apoptotic bodies and expressions of apoptosis-related proteins (caspase-3 and caspase-9) in IgAN model. The fibrosis indexes (transforming growth factor ß-1 (TGF-ß1), Collagen-IV (CoI-IV) and Fibronectin-1) of kidney were remarkably suppressed in IgAN rats treated with hirudin compared with IgAN rats with no further treatment. IgAN rats exhibited remarkably increased inflammatory factors (IL-1ß, IL-6, and IL-18), while hirudin treatment significantly alleviated these alterations. Moreover, the reduced levels of CD4+CD25+Foxp3+ Treg and CD4+IFN-γ+ Th1/CD4+IL-4+ Th2 could be reversed by hirudin in IgAN model. Furthermore, in the process of IgAN, hirudin could inactivate various pathways (IκBα, NF-κB, TNF-α, and VCAM-1) compared with IgAN model group. Taken together, our study indicated that hirudin could ameliorate IgAN through suppressing fibrosis and inflammatory response. These findings provide a new therapeutic method to treat IgAN.

Autoantibody Profile of Adult Patients With Childhood Onset Type 2 Autoimmune Hepatitis.

BACKGROUND: Anti-liver kidney microsome (anti-LKM) autoantibodies are a distinguishing feature of type II autoimmune hepatitis (AIH-2). However, the levels of anti-LKM-1 in adult AIH-2 patients and their role in liver immunopathology remain equivocal. The aim of the study was to survey the autoantibody profile and the activity of liver disease in adult patients diagnosed with AIH-2 at childhood. METHODS: The autoantibody profile of adults was compared with the autoantibodies of the pediatric period. Liver function test, Immunoglobulin G (IgG), and gamma globulins were evaluated at the AIH presentation, at the age of 18 years, and at the current adult visit. RESULTS: All ten patients tested positive for LKM-1 at least once during the pediatric period. At the adult visit, four patients lost autoantibody positivity. LKM-1 was positive in four, liver cytosol antigen 1 (LC-1) in two, soluble liver antigen in one, and antinuclear antigen in one patient. Additionally three patients with LKM-1 and one patient without LKM-1 were positive for AMA-M2 (where AMA is antimitochondrial antibodies) Immunoglobulin M (IgM). Liver function markedly improved at 18 years and adult visit compared with initial diagnosis of AIH with only a mild decrease of IgG. The six adult patients positive for at least one autoantibody had statistically lower aspartate aminotransferase (AST) and gamma-glutamyltranspeptidase (GGTP) than the four patients autoantibody negative (AST: 52 vs. 88 IU/l, P < 0.05; GGTP 19 vs. 163 IU/l, P < 0.05). CONCLUSION: LKM-1 positivity is not a stable condition in all patients with AIH-2. Patients who remained autoantibody positive had better liver function tests than those who lost their positivity. The presence of AMA-M2 autoantibodies suggest that development of AIH/Primary Biliary Cirrhosis (PBC) overlap syndrome should be considered.

An asymmetric antibody repertoire is shaped between plasmablasts and plasma cells after secondary immunization with (4-hydroxy-3-nitrophenyl)acetyl chicken γ-globulin.

Studies on the structural basis of antibody affinity maturation have been carried out by measuring the affinity of secreted antibodies, and information on structures has often been obtained from nucleotide sequences of BCRs of memory B cells. We considered it important to establish whether the repertoire of secreted antibodies from plasma cells is really in accord with that of BCRs on memory B cells at the same time points post-immunization. We isolated plasma cells secreting antibodies specific to (4-hydroxy-3-nitrophenyl)acetyl (NP) hapten by affinity matrix technology using biotin-anti-CD138 and streptavidin-NP-allophycocyanin, to which anti-NP antibodies secreted by autologous plasma cells bound preferentially. We found that plasmablasts occupied >90% of the antibody-secreting cell compartment in the primary response and that they secreted antibodies whose VH regions were encoded by V186.2(+)Tyr95(+) sequences, which provided an increase in the medium level of affinity by somatic hypermutation (SHM) of heavy chains at position 33. After secondary immunization, a further increase in antibody affinity was observed, which was explained by the appearance of a number of plasma cells secreting V186.2(+)Gly95(+) antibodies that acquired high affinity by multiple SHMs as well as plasmablasts secreting V186.2(+)Tyr95(+) antibodies. However, we did not detect any plasmablasts secreting V186.2(+)Gly95(+) antibodies, showing that plasmablasts and plasma cells have a different antibody repertoire, i.e. their respective repertoires are asymmetric. On the basis of these findings, we discussed the relationship between the BCR affinity of memory B cells and plasmablasts as well as plasma cells as pertaining to their ontogeny.

Effect of poly(amidoamine) dendrimers on the structure and activity of immune molecules.

BACKGROUND: Poly(amidoamine) (PAMAM) dendrimers are widely used biomedical polymers, which are extensively applied in drug delivery, gene delivery, contrast agent, etc. In these biomedical applications, the bio-safety of the PAMAM dendrimers is a critical issue, which affects not only their toxicity to the host but also the expected in vivo biofunctions of the materials. To clarify the bio-safety of PAMAM dendrimers, the effects of generation 5 PAMAM dendrimers with amine, hydroxyl or carboxyl groups on immune molecules were explored in this work. METHODS: Specifically, the effect of the PAMAM dendrimers on the secondary structure and conformation of immune molecule γ-globulin was studied by using ultraviolet-visible, fluorescence, and circular dichroism spectroscopies. The effect of the PAMAM dendrimers on complement activation was determined by enzyme-linked immunosorbent assay. Further, the effect of the PAMAM dendrimers on antigen-antibody reaction was studied by using human red blood cell agglutination assay. RESULTS: The results showed that, the PAMAM dendrimers could affect the secondary structure and conformation of γ-globulin, and inhibited complement activation. Generation 5 PAMAM dendrimer with carboxyl group at 10mg/mL impaired red blood cell (RBC) antigen-antibody reaction. CONCLUSIONS: From these results, the effects of the PAMAM dendrimers on immune molecules depend on their bulk structure and surface groups. GENERAL SIGNIFICANCE: This work provides important information for the immunocompatibility evaluation, preclinical design, and clinical applications of PAMAM dendrimers.

Anti-thymocyte gamma-globulin may prevent antibody production after heart transplantation.

BACKGROUND: Rabbit anti-thymocyte globulin (RATG) has been used as induction therapy in heart transplantation. RATG is polyclonal and has been postulated to have anti-humoral properties by preventing the production of circulating antibodies after heart transplant. Thus, we reviewed our patients who received RATG induction therapy and compared them with those who did not receive therapy for post-transplant de novo antibody production. METHODS: Between January 1, 2006, and January 1, 2013, we assessed 196 non-sensitized heart transplant recipients and divided them into those who received 3 to 5 days of RATG induction therapy mostly due to renal insufficiency (n = 35) versus patients who did not receive therapy (n = 161). All patients were given tacrolimus, mycophenolate mofetil, and corticosteroids. Post-transplant circulating antibodies were routinely monitored at 1, 3, 6, and 12 months after heart transplantation; 1-year and 3-year end points were assessed. RESULTS: The RATG-treated group had a significantly higher 12-month freedom from de novo antibody production compared with the patients who did not receive RATG induction (89% vs 71%, log-rank P = .043); however there was no significant difference for 12-month freedom from de novo donor-specific antibody production (91% vs 88%, log-rank P = .541). Treated rejection rates in the first-year were comparable in both groups; 3-year actuarial survival, freedom from cardiac allograft vasculopathy, and freedom from non-fatal major adverse cardiac events were also similar between both groups. CONCLUSIONS: RATG induction therapy appears to reduce the production of de novo circulating antibodies in non-sensitized patients during the first year after heart transplantation. Although there were no short-term clinical differences between groups, there were imbalances in group characteristics and relatively short follow-up, which are limitations to this study. A randomized, clinical trial with longer follow-up in a larger cohort of patients is warranted.

gp49B-mediated negative regulation of antibody production by memory and marginal zone B cells.

The rapid Ab responses observed after primary and secondary immunizations are mainly derived from marginal zone (MZ) and memory B cells, respectively, but it is largely unknown how these responses are negatively regulated. Several inhibitory receptors have been identified and their roles have been studied, but mainly on follicular B cells and much less so on MZ B, and never on memory B cells. gp49B is an Ig superfamily member that contains two ITIMs in its cytoplasmic tail, and it has been shown to negatively regulate mast cell, macrophage, and NK cell responses. In this study, we demonstrate that gp49B is preferentially expressed on memory and MZ B cells. We show that gp49B(-/-) mice produce more IgM after a primary immunization and more IgM and IgG1 after a secondary immunization than gp49B(+/+) mice in T cell-dependent immune responses. Memory and MZ B cells from gp49B(-/-) mice also produce more Abs upon in vitro stimulation with CD40 than those from gp49B(+/+) mice. The in vitro IgM production by MZ B cells from gp49B(+/+), but not gp49B(-/-), mice is suppressed by interaction with a putative gp49B ligand, the integrin αvß3 heterodimer. In addition, gp49B(-/-) mice exhibited exaggerated IgE production in the memory recall response. These results suggest that plasma cell development from memory and MZ B cells, as well as subsequent Ab production, are suppressed via gp49B. In memory B cells, this suppression also prevents excessive IgE production, thus curtailing allergic diseases.

Quinoline-3-carboxamides modulate primary T cell-dependent B cell responses but do not inhibit functional immunity.

The effect of a quinoline-3-carboxamide on the T cell-dependent B cell response was investigated in C57BL/6 mice after NP-CGG immunization. The primary serum response to the hapten was slightly inhibited by treatment with a quinoline-3-carboxamide. This inhibition was paralleled by reduced numbers of germinal centre (GC) B cells and follicular T cells in the spleen up to 21 days after immunization. Also, both the number of GCs formed and their size were reduced by quinoline-3-carboxamide treatment. In contrast to the observation in the primary immune response, there was no inhibitory effect on the secondary immune response. These data could help to explain how quinoline-3-carboxamides can modulate immune function in autoimmune diseases without being immunosuppressive.

Pivotal role of HIV and EBV replication in the long-term persistence of monoclonal gammopathy in patients on antiretroviral therapy.

A high prevalence of monoclonal gammopathy (MG) has been observed in HIV-infected patients. We explored the conditions associated with long-term persistence of serum monoclonal protein (M protein) in HIV-infected patients on antiretroviral therapy (ART). Of 21 patients with MG, M protein disappeared in 12 patients (58%) over 5 years of ART. Higher level of serum γ-globulin and higher percentages of circulating plasmablasts and plasma cells were observed in patients with persistent MG compared with patients with transient MG. MG persistence was associated with the cumulative time of detectable plasma HIV RNA after ART initiation, detection of Epstein-Barr virus (EBV) DNA in plasma, and a high level of EBV DNA in B cells. Poor control of HIV replication and detectable EBV replication in plasma were both associated with long-term MG persistence in patients on ART. In the case of viral control, MG associated with HIV infection is usually transient.