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Results for “Immunity, Mucosal”

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PubMed2026

m6A RNA methylation modulates IFN-γ-stimulated intestinal epithelial cell-intrinsic antiparasitic defense.

N6-methyladenosine (m6A) RNA methylation is one of the most prevalent reversible post-transcriptional RNA modifications and has been recognized as a crucial regulator of host immune responses. Intestinal epithelial cells (IECs) constitute an important component of gastrointestinal mucosal immunity. Interferons (IFNs) play a central role in maintaining intestinal homeostasis, and m6A methylation status influences IFN-mediated cell-intrinsic defense. In this study, we investigated the potential role of m6A RNA modifications in IFN-γ-stimulated IEC-intrinsic defense. We observed significant alterations in the topology of the m6A mRNA methylome in murine IECs following IFN-γ stimulation. A subset of IFN-γ-stimulated immune gene transcripts exhibited increased m6A RNA methylation, including several members of the immunity-related GTPase family M (IRGM) genes. In addition, IFN-γ-responsive long non-coding RNAs may modulate the m6A methylation levels of multiple IFN-γ-stimulated immune transcripts. Enhanced m6A methylation of the Irgm2/3 transcripts was associated with strengthened cell-intrinsic defense against infection by the protozoan parasite Cryptosporidium. Notably, Cryptosporidium infection altered the host m6A mRNA methylome in IECs, thereby counteracting the IFN-γ-mediated defense response. Although the RNA levels of Irgm2/3 genes were upregulated, their m6A RNA methylation levels and protein expression were reduced in infected cells. This effect was associated with host delivery of dsRNAs derived from Cryptosporidium parvum virus 1, a virus harbored in the parasite. Collectively, our findings suggest that m6A methylation of RNA transcripts enhances IFN-γ-mediated IEC-intrinsic antiparasitic defense, while Cryptosporidium has evolved mechanisms to evade this response by suppressing m6A RNA methylation of IFN-γ-stimulated immune genes.

Animals↗

PubMed2026

Biofilm formation during pneumococcal carriage imprints naturally acquired humoral immunity.

Streptococcus pneumoniae (Spn) colonization of the nasopharynx is a prerequisite for transmission and invasive disease. To investigate how repeated asymptomatic colonization shapes immunity and influences bacterial traits, we developed the Repeated Asymptomatic Murine Pneumococcal Colonization (RAMPC3) model using strains belonging to serotypes: 2 (D39), 3 (WU2), and 4 (TIGR4). Sequential colonization revealed strain- and exposure-order-dependent effects on bacterial burden, with initial colonization yielding robust carriage and subsequent exposures resulting in diminished burden and rapid clearance. Humoral profiling demonstrated antigenic imprinting: the first colonizing strain largely determined IgG and IgA specificity against bacterial proteins, with minimal diversification or expansion after repeated exposures. Reactivity was strongest for biofilm-associated antigens correlating with each strain's biofilm-forming capacity. Notably, experiments using human sera from naturally colonized adults mirrored these findings, with reactivity favoring biofilm antigens independent from capsule. Partial protection as result of colonization was demonstrated as triple-colonized mice had reduced mortality following pneumococcal pneumonia challenge. Likewise, mice colonized with biofilm deficient versions of TIGR4 and then challenged intratracheally with a serotype 6A (6A-10) strain were more likely to develop bacteremia, underscoring the contribution of the biofilm-associated host response to immunity. Finally, IgA responses in nasal-associated lymphoid tissue paralleled serum IgA patterns, validating systemic measurements as a proxy for mucosal immunity. These results reveal that biofilm formation during colonization is a key determinant of humoral immunity and contributes to systemic protection, providing insight into pneumococcal biology and informing strategies to design next-generation interventions.

Animals↗

PubMed2026

Parasites and allergies: a complex bidirectional relationship from evolutionary origins to modern therapeutics.

Parasites and allergic diseases are linked by a complex, bidirectional relationship shaped by long-term host-parasite coevolution. This review discusses how different parasites may either promote or attenuate allergic responses through immunological, epithelial, and microbiome-mediated mechanisms. IgE-mediated immunity, mast cell activation, eosinophilia, and pruritus may have evolved as protective responses against helminths and blood-feeding ectoparasites. In contrast, modern allergies may partly reflect misdirected responses to harmless environmental antigens. The effects of parasites on allergy are not uniform and depend on parasite type, infection site, exposure intensity and chronicity, host immune status, and the degree of host-parasite adaptation. Protozoa such as Giardia intestinalis may contribute to food allergy-related manifestations by disrupting the intestinal barrier, altering gut microbiota composition, and modifying mucosal immune responses, particularly in atopic individuals. In contrast, selected helminths may attenuate allergic inflammation by inducing regulatory T and B cells, anti-inflammatory cytokines, antigen-presenting cell modulation, and IgG4-associated mechanisms that can limit IgE-mediated effector responses. Molecular similarities between parasite-derived antigens and environmental allergens, including conserved protein families and carbohydrate epitopes, may contribute to cross-reactive IgE responses and complicate allergy diagnostics. Therefore, current research is shifting from live helminth therapy toward defined parasite-derived molecules and immunomodulatory pathways that may inspire safer and more controlled therapeutic strategies. A clearer understanding of parasite-allergy interactions may improve diagnostic interpretation and support the development of new approaches to the management of allergic disease.

Humans↗

PubMed2026

Bacterial Outer Membrane Vesicles in Colorectal Cancer: Interdomain Communication Hubs in Pathogenesis and Immunotherapy.

The complex interaction between the intestinal microbiota and host mucosal immunity plays a defining role in colorectal cancer (CRC) development and therapeutic outcomes. Recently, bacterial outer membrane vesicles (OMVs)-nano-sized, lipid-bilayered extracellular particulates released by both commensal and pathogenic microorganisms-have emerged as critical long-range signaling vehicles within the gut. This review provides a comprehensive synthesis of the dual functionalities of OMVs in CRC pathogenesis and oncology. Mechanistically, pathogenic OMVs cross compromised mucosal barriers to drive horizontal gene transfer (HGT) of chimeric episomes, such as SPHINX DNAs and Bovine Meat and Milk Factors (BMMFs), thereby promoting genomic instability and neoplastic transformation. Conversely, there is a paradigm shift toward exploiting next-generation probiotic and engineered OMVs as highly tunable therapeutic platforms. By combining cutting-edge bioengineering strategies-such as biomimetic mineralization to neutralize local tissue acidity and chemotherapeutic packaging-these nanovectors effectively reprogram the immunosuppressive tumor microenvironment (TME). Specifically, optimized OMVs modulate macrophage polarization from an M2 to an M1 phenotype and stimulate CXCL10-mediated CD8+ T-cell infiltration, effectively turning immunologically "cold" tumors "hot." Finally, the great translational challenges regarding systemic endotoxicity, scalability, and target delivery, providing a strategic approach for the integration of OMV-based platforms into synergistic immune checkpoint inhibition regimens.

Colon cancer↗

PubMed2025

Immunosuppressants Rewire the Gut Microbiome-Alloimmune Axis Through Time-Dependent and Tissue-Specific Mechanisms.

BACKGROUND: Lifelong immunosuppressive therapy is required to prevent allograft rejection in organ transplantation. Current immunosuppressants effectively suppress adaptive and innate immune responses, but their broad, antigen-non-specific effects often result in severe off-target complications. It remains a significant unmet medical need in transplant medicine. RESULTS: In this study we investigated immunosuppressant effects of four major immunosuppressant classes, including tacrolimus, prednisone, mycophenolate mofetil (MMF), and fingolimod (FTY), on the gut microbiome, metabolic pathways, lymphoid architecture and lymphocyte trafficking after up to 30-day chronic exposure. Despite their distinct mechanisms of action and not designed to target the gut, all immunosuppressive drugs induced profound and time-dependent alterations in both intestine gene expression and gut microbiome composition. Progressive alterations from moderate early, drug-specific changes to a strikingly convergent microbial dysbiosis, marked by significant expansion of pathobionts of Muribaculaceae, occurred across all drug classes. Concurrently, all drugs uniformly induced significant suppression of mucosal immunity including B cell, immunoglobulin, and antigen recognition. Time-dependent changes in lymph node (LN) reorganization and cellular composition were also observed, marked by a progressive shift toward pro-inflammatory phenotypes in gut-draining mesenteric LNs and a gradual loss of tolerogenic architecture in peripheral LNs. Drug-specific metabolic alterations and distinct phases of intestinal transcriptional responses were also characterized. Notably, MMF and FTY demonstrated the most robust immunomodulatory properties, and were able to suppress alloantigen-induced inflammation through mediating regulatory T cell distribution and LN remodeling. CONCLUSIONS: Together, these findings highlight the underappreciated complexity and temporal dynamics immunosuppressants effects, particularly their impact on the gut and compartmentalized regulation of alloimmune in lymphoid tissues. Understanding these relationships offers new opportunities for refining immunosuppressive strategies to reduce treatment-related off-target complications and improve long-term organ transplant outcomes.

gut dysbiosis↗

PubMed2026

Immunogenicity and efficacy of a rabies-based vaccine against highly pathogenic influenza H5N1 virus.

The recent spillover of highly pathogenic influenza A/H5N1 (HPAI-H5N1) viruses to cattle, other mammals, and humans poses a major risk to animal and human health. Virus adaptation to new species highlights the need for effective vaccines for animals and humans. We recently developed a rabies virus-based H5 vaccine encoding the HPAI-H5 antigen and presenting it on the surface of the rabies virus particle. To test the immunogenicity and efficacy of the vaccine in eliciting systemic and mucosal immune response, we vaccinated mice intramuscularly or intranasally with either live or inactivated and adjuvanted vaccine. The vaccine elicited neutralizing antibodies against RABV and H5N1 Influenza virus and protected mice from a lethal challenge with PR8 recombinants reassorted with the HA of clade 1 (Viet Nam 1203) or clade 2.3.4.4b HPAI-H5N1 viruses, highlighting its potential use in mitigating the risk of HPAI-H5N1 pandemic.

Influenza A Virus, H5N1 Subtype↗

PubMed1976

Atopic disorders and adult coeliac disease.

A history of asthma, hay fever, and flexural eczema was significantly more common in patients with adult coeliac disease (A.C.D.) than in normal controls. Autoantibodies were also more common in A.C.D. First-degree relatives of A.C.D. patients were more likely than controls to have atopic disorders. A deficiency of local mucosal immunity due to abnormal IgA responses may underly this association between A.C.D. and atopy.

Adult↗

PubMed1978

IgA protease production as a characteristic distinguishing pathogenic from harmless neisseriaceae.

IgA proteases are extracellular enzymes of bacteria that have human immunoglobulin A of the IgA1 subclass as their only known substrate. The identification of this enzyme in neisseria prompted us to determine whether IgA protease production correlates with pathogenicity within this genus. Multiple clinical isolates of Neisseria gonorrhoeae, N. meningitidis and eight species of non-pathogenic neisseria that commonly colonize the normal human nasopharynx were examined for IgA protease activity. All N. gonorrhoeae and N. meningitidis strains were enzyme positive; all non-pathogenic strains were negative. Among meningococci, the enzyme occurred in strains carried harmlessly in the nasopharynx as well as those isolated from systemic infections. Because mucosal immune defense is largely mediated by antibodies of the IgA isotype, the finding that IgA protease activity is linked specifically to the pathogenic neisseria suggests that the enzyme may be involved in the pathogenesis of neisserial infection.

Gonorrhea↗

PubMed2025

Bacteriophages as vaccine platforms: Opportunities and challenges in translation.

Bacteriophages (phages) have recently received increased interest as versatile candidates for vaccine development. Their inherent characteristics, such as ease of genetic manipulation, high-density antigen display, intrinsic immunostimulatory properties, demonstrated human safety, and scalability in bacterial hosts, make them attractive as next-generation vaccine platforms. Additionally, their cost-effective production, stability, and existing regulatory approval for food and compassionate phage therapy provide a strong foundation for further development of phage-based vaccines. This commentary summarizes the types of phages, the strategies used, and current advances in phage-based vaccine development for viral and bacterial targets, and discusses the promises and challenges of this platform for novel vaccine development. Phage-based vaccines represent an innovative and promising platform for vaccine development to address significant medical and public health challenges, particularly in antimicrobial resistance, pandemic preparedness, and One Health. Accumulative experimental data have demonstrated that phage-based vaccines induce specific cellular, humoral, and mucosal immune responses at magnitudes comparable to those induced by other vaccine platforms. However, a better understanding of phage biology (interactions with the human immune system and microbiome), more carefully designed preclinical studies, Good Manufacturing Practice production development, the regulatory framework, and ultimately clinical trials are needed before the full potential of this platform is realized.

Animals↗

PubMed2025

ITIH4 alleviates OVA-induced asthma by regulating lung-gut microbiota.

BACKGROUND: Inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4), a Type 2 acute phase protein, is critical for resolving inflammation and promoting tissue repair. While its role in chronic respiratory diseases is recognized, its effects on asthma remain unclear. This study investigated the effects of ITIH4 on the modulation of lung and gut microbiota, the attenuation of allergic inflammation, and the improvement of respiratory outcomes in an asthma mouse model. METHODS: Six-week-old male Balb/c mice were divided into five groups: control, ITIH4, ovalbumin (OVA), and two OVA + ITIH4 treatment groups at different doses. Lung function and oxygen saturation were measured, and bronchoalveolar lavage fluid (BALF) was analyzed for white blood cell counts and cytokines. Lung and gut microbiota were profiled using 16 S rRNA gene sequencing, and short-chain fatty acids (SCFAs) were measured using gas chromatography-mass spectrometry (GC-MS). Proteomic profiling of intestinal tissues was conducted to identify ITIH4-associated signaling pathways. RESULTS: ITIH4 administration significantly mitigated OVA-induced asthma symptoms by reducing weight loss, airway resistance, and tissue damping (p < 0.05). Histological analysis showed decreased airway wall thickening and lung injury scores (p < 0.05). ITIH4 also lowered BALF eosinophils and lymphocytes, IgE, and Th2 cytokines (IL-4, IL-5, and IL-13) (p < 0.05). ITIH4 treatment modulated microbiome composition, enriching Gram-positive taxa (Nocardioidaceae and Acholeplasmataceae) and depleting Gram-negative Helicobacteraceae (p < 0.05). SCFAs correlated with microbiome alterations, notably reduced 4-methylpentanoic acid levels (p < 0.05). Proteomic analysis revealed a dose-dependent activation of granzyme A signaling and suppression of metabolic and solute transport pathways. CONCLUSIONS: ITIH4 ameliorates asthma symptoms by modulating lung and gut microbiota, dampening Th2-driven inflammation, and restoring mucosal immune balance. These findings support ITIH4 as a potential candidate for microbiome-targeted asthma therapy.

Animals↗

PubMed1978

Prevention of bacterial infections of mucosal surfaces by immune secretory IgA.

1) Colonization and diarrhea in the rabbit due to RDEC-1 strain E. coli elicits an immune response that prevents subsequent infection with the same bacterium. 2) RDEC-1 and InvEC strain colonization of the gut of pregnant rabbits is followed by the appearance, post-delivery, of anti-InvEC or RDEC-1 strain s-IgA in the milk, some of which was able to agglutinate as many as 3.4 X 10(11) bacteria per mg of s-IgA. 3) Immune s-IgA, given by the orogastric route to rabbits, is able to survive the digestive enzymes of the gastrointestinal tract to prevent the colonization and diarrhea that follows the inoculation of InvEC and RDEC-1 strains. One possible explanation for the protective effect of s-IgA is the in vivo agglutination of bacteria in the lumen of the gastrointestinal tract.

Animals↗

PubMed1978

Induction of a mucosal antitoxin response and its role in immunity to experimental canine cholera.

The induction of a jejunal antitoxin response was studied in dogs immunized with cholera toxin or toxoid. Single doses of toxoid given subcutaneously (s.c.) or of toxin given intraluminally (i.l.) were each effective in priming the mucosal immune system, whereas toxoid given i.l. was much less effective. In contrast, toxin and toxoid given i.l. were each effective as booster antigens. The local secondary response was rapid and brief, the peak occurring at about 7 days after i.l. boosting and declining by 90% after 2 more weeks. After s.c. priming and i.l. boosting with toxoid, antitoxin-containing plasma cells appeared predominantly in the portion of jejunum exposed to the i.l. booster. The appearance of antitoxin-containing plasma cells in jejunal lamina propria correlated with the amount of antitoxin recovered in jejunal washings which, in turn, correlated with protection against challenge with cholera toxin. Thus, lamina propria antitoxin-containing plasma cells appeared to be the source of protective antitoxin. However, after sequential s.c.-oral immunization with toxoid, protection against challenge with Vibrio cholerae far outlasted the major systemic and local antitoxin responses and was not obviously explained by either. These studies reveal methods for induction of a mucosal antitoxin response, but leave in question the mechanism of prolonged protection induced by s.c.-oral immunization of dogs.

Animals↗

PubMed2024

Tuft cell acetylcholine is released into the gut lumen to promote anti-helminth immunity.

Upon parasitic helminth infection, activated intestinal tuft cells secrete interleukin-25 (IL-25), which initiates a type 2 immune response during which lamina propria type 2 innate lymphoid cells (ILC2s) produce IL-13. This causes epithelial remodeling, including tuft cell hyperplasia, the function of which is unknown. We identified a cholinergic effector function of tuft cells, which are the only epithelial cells that expressed choline acetyltransferase (ChAT). During parasite infection, mice with epithelial-specific deletion of ChAT had increased worm burden, fitness, and fecal egg counts, even though type 2 immune responses were comparable. Mechanistically, IL-13-amplified tuft cells release acetylcholine (ACh) into the gut lumen. Finally, we demonstrated a direct effect of ACh on worms, which reduced their fecundity via helminth-expressed muscarinic ACh receptors. Thus, tuft cells are sentinels in naive mice, and their amplification upon helminth infection provides an additional type 2 immune response effector function.

Animals↗

PubMed2011

Mucosal memory CD8⁺ T cells are selected in the periphery by an MHC class I molecule.

The presence of immune memory at pathogen-entry sites is a prerequisite for protection. Nevertheless, the mechanisms that warrant immunity at peripheral interfaces are not understood. Here we show that the nonclassical major histocompatibility complex (MHC) class I molecule thymus leukemia antigen (TL), induced on dendritic cells interacting with CD8αα on activated CD8αβ(+) T cells, mediated affinity-based selection of memory precursor cells. Furthermore, constitutive expression of TL on epithelial cells led to continued selection of mature CD8αβ(+) memory T cells. The memory process driven by TL and CD8αα was essential for the generation of CD8αβ(+) memory T cells in the intestine and the accumulation of highly antigen-sensitive CD8αβ(+) memory T cells that form the first line of defense at the largest entry port for pathogens.

Animals↗

PubMed2026

The Potential Link Between Eosinophilic Esophagitis and Food Allergy: Inflammatory Pathogenesis and Management.

Eosinophilic esophagitis (EoE) has transitioned from an isolated gastrointestinal disorder to a recognized type 2 immune-mediated allergic disease, most likely representing a late manifestation of the atopic march. This comprehensive review examines the complex inflammatory pathogenesis linking EoE and food allergy, and critically discusses the mechanisms of disease induction, dietary treatments, and emerging clinical challenges. While genome-wide association studies identify shared susceptibility loci with classic atopy, EoE exhibits distinct tissue-specific pathways, particularly dominated by the local interleukin (IL)-13 axis and highly esophagus-selective proteases like Calpain-14. This unique immunological interplay is clinically epitomized by food oral immunotherapy (OIT)-induced EoE. During OIT, systemic immune reprogramming successfully drives immune tolerance-marked by a robust increase in plasma food-specific IgG4-but fails at the local level, due to the persistence of pathogenic Th2 cells and aberrant mucosal IgG4 immune complex deposition within the esophageal lamina propria. Regarding therapeutic management, conventional skin and serum allergy testing remain highly inaccurate in identifying dietary triggers, rendering test-guided diets ineffective. Conversely, empiric elimination diets achieve robust histological remission, ranging from standardized six-food restrictions to pragmatic single-food approaches targeting cow's milk. Furthermore, novel insights into industrial milk processing (such as UHT sterilization and homogenization) and specific beta-casein genetic variants (A1 vs A2) highlight how altered protein structures generate neoantigens that accelerate esophageal immunogenicity. In conclusion, decoding the divergent immunological mechanisms operating in the refractory esophagus is essential to move beyond trial-and-error dietary interventions towards non-invasive monitoring tools, precision medicine, and optimized biological therapies in EoE management.

Calpain14↗

PubMed2026

Identification and functional characterization of a novel antiviral chicken interferon-υ.

Interferons are critical mediators of antiviral immunity in vertebrates. While type IV interferon (IFN-υ) has been identified in fish and amphibians, its existence and function in chickens remained unknown. Through systematic genomic screening, we identified and cloned a novel chicken interferon gene, designated ChIFN-υ. Phylogenetic analysis placed ChIFN-υ within a distinct clade alongside zebrafish and clawed frog IFN-υ, confirming its identity as a type IV interferon, with minimal homology to classical type I, II, or III IFNs. Expression profiling revealed constitutive ChIFN-υ expression in mucosal and immune tissues of healthy chickens, exhibiting a distinct developmental shift: highest in trachea and small intestine in 1-day-old chicks, shifting to spleen and lung in 4-week-old chickens. ChIFN-υ expression was strongly upregulated following H9N2 AIV infection. Functionally, recombinant ChIFN-υ protein activated the interferon-stimulated response element (ISRE) and Mx promoter in a dose-dependent manner and significantly inhibited the replication of both vesicular stomatitis virus (VSV) and H9N2 AIV in DF-1 cells. In vivo, early treatment with exogenous ChIFN-υ significantly reduced pulmonary and tracheal viral loads and decreased oropharyngeal and cloacal virus shedding in H9N2-infected chickens. In conclusion, this study identifies and functionally characterizes the type IV interferon in chickens, elucidating the evolutionary status, regulated expression, and antiviral efficacy of ChIFN-υ. These findings highlight its potential as a candidate for developing interferon-based therapies against avian viral diseases.

Animals↗

PubMed2024

Intranasal neomycin evokes broad-spectrum antiviral immunity in the upper respiratory tract.

Respiratory virus infections in humans cause a broad-spectrum of diseases that result in substantial morbidity and mortality annually worldwide. To reduce the global burden of respiratory viral diseases, preventative and therapeutic interventions that are accessible and effective are urgently needed, especially in countries that are disproportionately affected. Repurposing generic medicine has the potential to bring new treatments for infectious diseases to patients efficiently and equitably. In this study, we found that intranasal delivery of neomycin, a generic aminoglycoside antibiotic, induces the expression of interferon-stimulated genes (ISGs) in the nasal mucosa that is independent of the commensal microbiota. Prophylactic or therapeutic administration of neomycin provided significant protection against upper respiratory infection and lethal disease in a mouse model of COVID-19. Furthermore, neomycin treatment protected Mx1 congenic mice from upper and lower respiratory infections with a highly virulent strain of influenza A virus. In Syrian hamsters, neomycin treatment potently mitigated contact transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In healthy humans, intranasal application of neomycin-containing Neosporin ointment was well tolerated and effective at inducing ISG expression in the nose in a subset of participants. These findings suggest that neomycin has the potential to be harnessed as a host-directed antiviral strategy for the prevention and treatment of respiratory viral infections.

Animals↗

PubMed1975

Immunologic and virologic aspects of secretory immune system in human respiratory tract.

Many external mucosal surfaces in man are replete with immunoglobulin containing plasma cells and thymic dependent (T) lymphocytes. Immunization with viral vaccines administered via different routes have indicated that viral specific secretory immunoglobulins particularly of gamma A class are synthesized locally in the external mucosal surfaces. Local availability of viral antigens especially after local mucosal immunization appears to be the most effective means of inducing viral specific secretory antibody responses in the respiratory tract. Similarly, local induction of specific cellular immune responses in the respiratory tract and tonsilar lymphoid cells has been demonstrated after intranasal immunization with viral vaccines. Generally, the locally induced secretory antibody and cell-mediated immune responses in the respiratory tract appear to be independent of the immune response in the systemic sites, with little or no contribution from circulating immunoglobulins and T-cells. Information obtained after natural or vaccine induced infections with polio, influenza, measles, rubella and other viruses suggest that the outcome of a reinfection challenge in the respiratory and alimentary tracts is determined to a major extent by the presence and level of pre-existing secretory antibody. Although the precise role of locally induced cellular immunity in protection against viral infection remains to be determined, these observations suggest that the mechanism of immunologic defence in external surfaces may be mediated largely through specific secretory immunoglobulin and cellular immune response.

Agammaglobulinemia↗