Agaricus blazei as a Vaccine Adjuvant: Research

Agaricus blazei and Immune Function

2x Vaccine Boost

When co-administered with DNA vaccines in mice, Agaricus blazei extract significantly increased both antibody production and T cell proliferation compared to vaccine alone, across two independent vaccine models.

Chen et al., International Immunopharmacology, 2004

HBV + FMDV

two vaccine models showed enhanced responses

PFC p<0.01

antibody-producing cells increased in spleen

No Human Data

all vaccine adjuvant studies are in mice

Chen et al., International Immunopharmacology, 2004

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Vaccine adjuvants are compounds added to vaccines to strengthen the immune response. Without adjuvants, many vaccines produce weak or short-lived immunity. The most widely used adjuvant in human vaccines is aluminum salts (alum), which has been used since the 1920s. But alum primarily boosts antibody responses (humoral immunity) and does a poor job of activating T cell responses (cellular immunity). This limitation has driven a search for new adjuvants that can activate both arms of the immune system.

Beta-glucans from mushrooms, including Agaricus blazei Murill (ABM), are among the candidates being studied. ABM beta-glucans activate dendritic cells through Dectin-1 receptors, triggering both innate and adaptive immune responses. In mouse studies, co-administering ABM extract with DNA vaccines significantly boosted both antibody production and T cell proliferation. No human vaccine adjuvant trial has been conducted with ABM. The evidence is entirely preclinical, but the mechanism is well-mapped. For the broader picture of how ABM activates NK cells, the NK cell pathway builds on the same dendritic cell biology.

What Makes a Good Vaccine Adjuvant

Adjuvants work by mimicking danger signals that tell the immune system a real threat is present. Pattern recognition receptors (PRRs) on dendritic cells and macrophages evolved to detect conserved molecular patterns from pathogens: bacterial cell wall components, viral RNA, fungal polysaccharides. When these receptors are activated, dendritic cells mature, migrate to lymph nodes, and present antigens to T cells with full co-stimulatory signals.

An ideal adjuvant activates both:

• Humoral immunity: B cells producing antibodies that neutralize pathogens
• Cellular immunity: CD4+ T helper cells that coordinate the response, and CD8+ cytotoxic T cells that kill infected cells directly

Most current adjuvants favor one arm over the other. Alum drives Th2 responses (antibodies). Some newer adjuvants (like AS01 in the shingles vaccine) activate Th1 responses (cellular immunity). Beta-glucans are interesting because they activate dendritic cells in a way that theoretically supports both arms.

ABM and Antibody-Producing Cells

The earliest evidence for ABM's adjuvant potential came from Nakajima and colleagues in 2002.^[1] They tested hot water-soluble extracts from dried ABM on antibody production against sheep red blood cells (SRBC), a standard immunological test antigen.

Key findings:

• ABM extract administered intraperitoneally at 25 mg/kg significantly increased plaque-forming cells (PFC) in the spleen (p < 0.01), meaning more B cells were actively producing antibodies
• Mac-1-positive cells (macrophages) increased significantly (p < 0.01)
• CD25-positive cells (activated T cells) increased significantly (p < 0.001)
• CD19-positive cells (B cells) showed no difference, suggesting ABM did not expand B cell numbers but rather increased their antibody secretion per cell
• ABM extract upregulated IL-6 and IL-1beta mRNA in both peritoneal macrophages and spleen cells

The mechanism: ABM stimulates macrophages to produce IL-6 and IL-1beta. IL-6 is a critical B cell differentiation factor that drives antibody-secreting plasma cell development. IL-1beta activates T cells and enhances antigen presentation. The result is more antibody production without simply expanding B cell populations. The Toll-like receptor biology underlying this macrophage activation is explored in a dedicated article.

DNA Vaccine Enhancement: Hepatitis B

Chen, Shao, and Su published the first vaccine-specific adjuvant study with ABM in 2004.^[2] They co-administered ABM extract with a DNA vaccine encoding hepatitis B virus core antigen (HBcAg) in BALB/c mice.

DNA vaccines work by injecting plasmid DNA encoding a pathogen protein. Host cells take up the DNA, transcribe and translate it, and present the resulting protein to the immune system. DNA vaccines are attractive because they are cheap, stable, and easy to produce. Their weakness is that they often produce weak immune responses in larger animals and humans, which is why adjuvants are critical.

Compared to mice receiving HBcAg DNA vaccine alone:

• Mice receiving vaccine plus ABM extract showed significantly increased HBcAg-specific antibody responses
• T cell proliferation in response to HBcAg restimulation was also significantly increased
• Both humoral (antibody) and cellular (T cell) arms of the immune response were enhanced

This dual enhancement is the most important feature. DNA vaccines typically induce good T cell responses but weak antibody responses. ABM extract improved both, which aligns with its mechanism of activating dendritic cells that can prime both B cells (for antibodies) and T cells (for cellular immunity).

DNA Vaccine Enhancement: Foot-and-Mouth Disease

Chen and Shao followed up in 2006 with the same approach applied to a veterinary vaccine.^[3] They co-administered ABM extract with a DNA vaccine against foot-and-mouth disease virus (FMDV) in BALB/c mice.

The results replicated the hepatitis B findings:

• FMDV-specific antibody response was significantly increased in mice receiving vaccine plus ABM extract
• T cell proliferation against FMDV antigens was significantly increased
• The enhancement was consistent across both humoral and cellular immunity

Two independent vaccine models (hepatitis B and FMDV) showing the same pattern of enhancement strengthens the evidence that ABM extract has genuine adjuvant properties rather than antigen-specific effects. The mechanism is nonspecific immune activation through beta-glucan-mediated dendritic cell priming, which would theoretically boost responses to any co-administered antigen.

The Dendritic Cell Connection

Forland and colleagues demonstrated in 2010 why ABM extract acts as an adjuvant at the cellular level.^[4] When human monocyte-derived dendritic cells were incubated with the ABM-based extract AndoSan, they produced dose-dependent increases in multiple pro-inflammatory cytokines.

The dendritic cell response to ABM exceeded that of bacterial lipopolysaccharide (LPS), one of the most potent known immune activators:

• G-CSF production: 10-fold higher with ABM than LPS
• TNF-alpha production: 2-fold higher with ABM than LPS
• IL-2, IL-8, IFN-gamma: comparable between ABM and LPS

Dendritic cells are the critical link between innate and adaptive immunity. They are the primary antigen-presenting cells that activate naive T cells and B cells. When dendritic cells are strongly activated (as ABM achieves), they present antigens more effectively, express more co-stimulatory molecules, and produce more cytokines that drive T cell differentiation. This is precisely what a vaccine adjuvant needs to do. The question of whether ABM is the most immunostimulating mushroom rests partly on these dendritic cell activation data.

Beta-Glucans as a Class of Adjuvants

Jin and colleagues reviewed the broader evidence for beta-glucans as vaccine adjuvants in 2018.^[5] Beta-glucans are recognized by multiple receptors on innate immune cells:

• Dectin-1: The primary beta-glucan receptor. Binding activates Syk kinase, CARD9, and NF-kB signaling
• Complement receptor 3 (CR3): Recognizes iC3b-opsonized beta-glucans
• CD5: A scavenger receptor that binds fungal beta-glucans
• Lactosylceramide: A glycosphingolipid receptor on neutrophils

The adjuvanticity of beta-glucans depends on their structure. Molecular weight, branching ratio, and solubility all affect receptor binding and immune activation. Water-insoluble beta-glucans (particulate, as found in whole mushroom preparations) generally have stronger immunostimulating activity than water-soluble forms.^[6]

This structural dependence explains why different ABM preparations show different potency. An aqueous extract may have weaker adjuvant properties than a whole mushroom preparation or an organic extract, because the water-insoluble beta-glucans with the strongest Dectin-1 binding are removed during aqueous extraction.

Human Evidence: Indirect

No human trial has tested ABM specifically as a vaccine adjuvant. The closest human evidence comes from the Tangen 2015 randomized trial in 40 multiple myeloma patients, where the ABM-based extract AndoSan increased expression of immunoglobulin genes and KIR genes on whole genome microarray.^[7]

Immunoglobulin gene upregulation suggests enhanced B cell activation and antibody production capacity, which is relevant to vaccine responses. KIR gene upregulation reflects NK cell priming. Both are consistent with the adjuvant mechanism demonstrated in mice, but this trial was not designed as a vaccine study and the patients were undergoing chemotherapy, which fundamentally alters immune function.

Yuminamochi and colleagues mapped the IL-12/IFN-gamma pathway by which ABM activates NK cells, showing that dendritic cells are the initiating cell type.^[8] This same dendritic cell activation is the basis for adjuvant function. The pathway is conserved across species, which provides biological plausibility for human translation, but mouse immune responses to beta-glucans are often stronger than human responses.

Limitations and Open Questions

The adjuvant evidence for ABM has specific gaps:

All vaccine studies are in mice. BALB/c mice are a standard model but have immune responses that do not always predict human responses. Mouse dendritic cells may respond more strongly to beta-glucans than human dendritic cells.

DNA vaccines are not the dominant platform. The ABM adjuvant studies used DNA vaccines, which are a minor vaccine platform in human medicine. Whether ABM would enhance responses to protein subunit vaccines, mRNA vaccines, or viral vector vaccines is untested.

Dose and timing are not optimized. The mouse studies co-administered ABM extract with the vaccine. Whether ABM would work as a pre-treatment (priming innate immunity before vaccination) or post-treatment (boosting responses after vaccination) is unknown.

No comparison to established adjuvants. ABM extract has not been compared head-to-head with alum, AS01, MF59, or other licensed adjuvants in terms of antibody titer, T cell responses, or protection against challenge. Without these comparisons, ABM's relative adjuvant potency is unknown.

Extract standardization is absent. Hetland noted that ABM extracts from different sources show "highly different biological potency."^[9] Without standardized extracts, results from one laboratory cannot be assumed to generalize. Approaches for immune-compromised patients face the same standardization challenge.

The Bottom Line

Agaricus blazei extract enhanced both antibody and T cell responses when co-administered with DNA vaccines against hepatitis B and foot-and-mouth disease in mice. The mechanism works through beta-glucan activation of dendritic cells via Dectin-1 receptors, producing cytokines that bridge innate and adaptive immunity. ABM extract stimulated dendritic cells more potently than bacterial LPS for several cytokines. No human vaccine adjuvant trial has been conducted with ABM, and all evidence remains preclinical.

Frequently Asked Questions

Can Agaricus blazei improve vaccine response?

In mice, ABM extract co-administered with DNA vaccines against hepatitis B and foot-and-mouth disease significantly increased both antibody production and T cell proliferation compared to vaccine alone (Chen et al., 2004; 2006). No human study has tested ABM as a vaccine adjuvant. The mechanism, dendritic cell activation via beta-glucan-Dectin-1 binding, is conserved across species but not yet validated in human vaccination.

How do beta-glucans work as vaccine adjuvants?

Beta-glucans bind to Dectin-1, CR3, and CD5 receptors on dendritic cells and macrophages, activating NF-kB signaling and cytokine production. This enhances antigen presentation to T cells and drives B cell differentiation into antibody-producing plasma cells. The result is stronger humoral (antibody) and cellular (T cell) immune responses to co-administered antigens (Jin et al., Vaccine, 2018).

Does Agaricus blazei increase antibody production?

ABM hot water extract significantly increased antibody-producing cells in mouse spleen (p < 0.01 at 25 mg/kg), with increased macrophage IL-6 and IL-1beta production driving the effect (Nakajima et al., 2002). In multiple myeloma patients, ABM-based extract AndoSan upregulated immunoglobulin genes on microarray (Tangen et al., 2015), suggesting enhanced antibody production capacity in humans.

Is Agaricus blazei better than alum as a vaccine adjuvant?

No head-to-head comparison between ABM extract and alum (or any licensed adjuvant) has been published. ABM theoretically offers an advantage by enhancing both Th1 (cellular) and Th2 (humoral) responses, while alum primarily boosts Th2 responses. Without direct comparison data on antibody titers, T cell activation, and protection against infection, relative potency is unknown.

Are there human studies on mushroom vaccine adjuvants?

No human clinical trial has tested any mushroom extract specifically as a vaccine adjuvant. The closest evidence comes from clinical trials showing that ABM extracts modulate immune biomarkers (NK cell activity, cytokine profiles, immunoglobulin gene expression) in cancer patients, but these were not vaccine studies. Beta-glucan vaccine adjuvant research remains at the preclinical stage for all mushroom species.

What types of vaccines could Agaricus blazei enhance?

ABM extract has only been tested with DNA vaccines in mice. DNA vaccines typically produce weak responses, so the adjuvant effect was notable. Whether ABM would similarly enhance protein subunit vaccines, mRNA vaccines, or inactivated virus vaccines is untested. The dendritic cell activation mechanism is antigen-nonspecific, suggesting it could theoretically boost responses to any vaccine platform.

Sources & References

1. 1RTHM-00048·Nakajima, A et al. (2002). “Effect of hot water extract from Agaricus blazei Murill on antibody-producing cells in mice..” International immunopharmacology.Study breakdown →PubMed →↩
2. 2RTHM-00068·Chen, L et al. (2004). “Coimmunization of Agaricus blazei Murill extract with hepatitis B virus core protein through DNA vaccine enhances cellular and humoral immune responses..” International immunopharmacology.Study breakdown →PubMed →↩
3. 3RTHM-00093·Chen, Liang et al. (2006). “Extract from Agaricus blazei Murill can enhance immune responses elicited by DNA vaccine against foot-and-mouth disease..” Veterinary immunology and immunopathology.Study breakdown →PubMed →↩
4. 4RTHM-00181·Førland, D T et al. (2010). “An extract based on the medicinal mushroom Agaricus blazei Murill stimulates monocyte-derived dendritic cells to cytokine and chemokine production in vitro..” Cytokine.Study breakdown →PubMed →↩
5. 5RTHM-00513·Jin, Yiming et al. (2018). “β-glucans as potential immunoadjuvants: A review on the adjuvanticity, structure-activity relationship and receptor recognition properties..” Vaccine.Study breakdown →PubMed →↩
6. 6RTHM-00333·Lee, Dong Hee et al. (2014). “Innate immunity induced by fungal β-glucans via dectin-1 signaling pathway..” International journal of medicinal mushrooms.Study breakdown →PubMed →↩
7. 7RTHM-00404·Tangen, Jon-Magnus et al. (2015). “Immunomodulatory effects of the Agaricus blazei Murrill-based mushroom extract AndoSan in patients with multiple myeloma undergoing high dose chemotherapy and autologous stem cell transplantation: a randomized, double blinded clinical study..” BioMed research international.Study breakdown →PubMed →↩
8. 8RTHM-00125·Yuminamochi, Eri et al. (2007). “Interleukin-12- and interferon-gamma-mediated natural killer cell activation by Agaricus blazei Murill..” Immunology.Study breakdown →PubMed →↩
9. 9RTHM-00133·Hetland, G et al. (2008). “Effects of the medicinal mushroom Agaricus blazei Murill on immunity, infection and cancer..” Scandinavian journal of immunology.Study breakdown →PubMed →↩