Benefits
Plasmacytoid dendritic cell activation
LC-Plasma uniquely activates pDCs — the innate immune cells most specialized for antiviral defense. Both live and heat-killed forms induce IFN-α production. The Kato 2025 meta-analysis confirmed significant pDC activation (CD86 and HLA-DR expression on pDCs) across multiple RCTs of healthy adults.
Reduced cold-like symptom days
Kato 2025 meta-analysis pooled data on common cold-like symptoms — sore throat, runny nose, cough, feverishness — and found reduction in cumulative symptom days for the LC-Plasma group vs placebo. Sugimura 2013 (foundational RCT) also reported fewer days of common cold-like symptoms during the yogurt consumption period.
Type I interferon induction
A 2025 confocal microscopy study confirmed LC-Plasma is uniquely internalized by pDCs (via phagocytosis) and induced significant IFN-α production (73.8 ± 2.5 pg/mL at recommended dose) — exceeding levels reported in serum of hospitalized COVID-19 patients. Other tested postbiotic strains showed no internalization or IFN-α response.
Postbiotic stability advantage
As a heat-killed paraprobiotic/postbiotic, LC-Plasma doesn't require cold-chain storage or live-cell viability. The activity is preserved through normal manufacturing and remains effective when incorporated into shelf-stable foods, beverages, and supplements — a practical advantage over conventional live probiotics for immune support.
Mechanism of action
TLR9 / pDC pathway activation
LC-Plasma is uniquely phagocytosed by plasmacytoid dendritic cells (pDCs) — a relatively rare immune cell population specialized for sensing viral nucleic acids and producing massive amounts of type I interferons. Most lactic acid bacteria activate myeloid DCs, not pDCs. LC-Plasma's distinctive cell wall components engage TLR9 and other intracellular pattern recognition receptors.
Type I interferon (IFN-α/β) cascade
Activated pDCs secrete IFN-α/β, which establish an antiviral state in surrounding cells: upregulating MHC class I, activating NK cells, priming cytotoxic T lymphocytes, and inducing antiviral effector proteins (PKR, OAS, Mx). This produces 'innate immune training' that primes defenses against viral pathogens including rhinovirus and coronaviruses.
Mucosal immune priming
Oral consumption of LC-Plasma provides direct contact with gut-associated lymphoid tissue (GALT), where pDCs can be activated and migrate to draining lymph nodes. This may explain the systemic immune effects from oral administration despite the heat-killed status precluding gut colonization.
Clinical trials
Individual participant data meta-analysis (Kato et al 2025, Frontiers in Immunology, doi:10.3389/fimmu.2025.1696989).
RCTs of oral LC-Plasma vs placebo in healthy adults. Searches through June 2024 across PubMed, Cochrane, J-Dream III, UMIN-CTR, and ICTRP.
Significant LC-Plasma effects on pDC activity (CD86 and HLA-DR expression on pDCs in peripheral blood). Reduced cumulative number of days with common cold-like symptoms (sore throat, runny nose, cough, feverishness). Authors concluded oral LC-Plasma activates pDCs and mitigates common cold-like symptoms in healthy adults — strongest pooled evidence for the immune mechanism translating to clinical outcomes.
Randomized, placebo-controlled, double-blind trial (Sugimura, Jounai, Ohshio, Tanaka, Suwa, Fujiwara 2013, Clin Immunol 149(3):509-518).
Healthy adult volunteers consuming yogurt fermented with L. lactis JCM5805 (LC-Plasma) vs placebo yogurt for 12 weeks.
Yogurt containing LC-Plasma activated pDC activity in vivo (peripheral blood pDC CD86 and HLA-DR expression). Effect was greater in subjects with low baseline pDC activity. IFN production capacity increased from baseline. Common cold morbidity risk was suppressed in the LC-Plasma group vs placebo. Established the foundational case that LC-Plasma activates pDCs in humans, not just in vitro.
Comparative postbiotic mechanism study (2025).
Five commercially available postbiotic products containing heat-killed bacterial strains tested for pDC activation and IFN-α induction. Confocal Z-stack imaging used to confirm bacterial internalization.
Among 5 tested postbiotic strains, ONLY LC-Plasma demonstrated significant internalization by pDCs and induced measurable IFN-α (73.8 ± 2.5 pg/mL at recommended dose). This effect was not observed with other strains, even at higher loads (1×10¹¹ cells). L. paracasei MCC1849 adhered to cell surface but was not internalized. IFN-α level induced by LC-Plasma exceeded serum levels in hospitalized COVID-19 patients, suggesting a meaningful antiviral immune contribution.
About this ingredient
Lactococcus lactis subsp. lactis JCM 5805 — strain Plasma (LC-Plasma) — is a heat-killed lactic acid bacterium developed by Kirin Holdings (Japan), commercially available as ImmuseLC-Plasma in dietary supplements and as iMUSE® branded foods/beverages in Japan. Importantly, LC-Plasma is administered in heat-killed (paraprobiotic / postbiotic) form — the immunological activity does not require live bacteria.
The strain was discovered through screening of lactic acid bacteria for the unusual property of activating plasmacytoid dendritic cells (pDCs), a rare immune cell population (~0.1-0.5% of peripheral blood mononuclear cells) specialized for antiviral defense via type I interferon production. Most other probiotic and postbiotic strains activate myeloid DCs but not pDCs. LC-Plasma was awarded the 2024 NIE New Ingredient Award, recognizing decades of Japanese research and the emerging postbiotic category.
EVIDENCE: 30+ studies, primarily Japanese. Kato 2025 meta-analysis of individual participant data is the strongest pooled evidence — confirms pDC activation effect translates to reduced cold-like symptom days. Sugimura 2013 established the pDC mechanism in humans.
The 2025 confocal imaging study provides striking mechanistic confirmation that LC-Plasma is uniquely internalized by pDCs and induces IFN-α at physiologically meaningful levels. 3/5 evidence rating reflects strong mechanism + meta-analysis support but limited US/European clinical trial replication. SAFETY: Heat-killed status eliminates the live-cell safety concerns of conventional probiotics.
Excellent tolerability across all reported trials. The postbiotic category positioning and shelf stability make LC-Plasma practical for functional foods, beverages, and supplements where cold-chain storage isn't feasible.