The classical complement pathway: molecular mechanisms & dependencies

How nutrients influence it

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Human evidence only

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

Where it participates (unsigned role)

At the end of infusion free serum antibody levels decreased, circulating immune complex levels increased and complement activation was observed, at approximately 1 to 4 hours after end of infusion increased expression of cytokines and chemokines, a 1.5 to 4-fold increase in neutrophil and monocyte counts and a broad activation of innate immune genes were observed, low-antibody subjects with levels below 20 micrograms per millilitre typically showed minimal changes except when their levels rose above 20 micrograms per millilitre after repeated dosing, mild-to-moderate infusion-related reactions occurred in subjects with antibody at or above 20 micrograms per millilitre, and premedications alleviated some of the infusion-related reactions but also inhibited cytokine responses.
Naturally occurring anti-beta-glucan IgG antibodies → Imprime PGG / BTH1677, a soluble yeast beta-(1->3)/(1->6)-glucan source_derived_draftungraded
Experimental context and source evidence
availability_state
biomarker_context Imported condition classification; unverified.
evidence_span
{"source_cache": "artifacts/glucan-research/30988115.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "bd9bd1b314472b30b2e3513ecb5e048178de145217473fa87379e0977d21f90d", "start_char": 0, "end_char": 1787, "text_sha256": "bd9bd1b314472b30b2e3513ecb5e048178de145217473fa87379e0977d21f90d"}
experimental_model
Single and multiple intravenous infusions in healthy volunteers stratified by pre-treatment antibody level, with and without premedication
exposure
Imprime PGG 4 milligrams per kilogram intravenously, with antihistamine and corticosteroid premedication in some subjects
limitations
Healthy volunteers and pharmacodynamic endpoints only. Nothing here measures a tumour outcome, so the antibody strata are not validated treatment-selection thresholds.
nutrient_topic
Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. · Beta-glucan
organism
Human
plain_language
Below a certain antibody level almost nothing happened; above it, the drug worked and also caused the infusion reactions.
primary_references
[bg-p30988115] Immune Pharmacodynamic Responses of the Novel Cancer Immunotherapeutic Imprime PGG in Healthy Volunteers. (2019). https://pubmed.ncbi.nlm.nih.gov/30988115/ DOI: 10.4049/jimmunol.1801533
tissue_or_cell_type
Peripheral blood
trigger_kind
biomarker_context Imported condition classification; unverified.
Beta-glucan: a structural family rather than an agent, what decides whether a bound glucan actually signals, the complement route that a cereal and a yeast preparation share, and the unequal human evidence behind each (2026-09-22) · lines 281–292
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single and multiple intravenous infusions in healthy volunteers stratified by pre-treatment antibody level, with and without premedication · source_derived_draft · unverified_draft
### bg-antibody-level-gates-the-response At the end of infusion free serum antibody levels decreased, circulating immune complex levels increased and complement activation was observed, at approximately 1 to 4 hours after end of infusion increased expression of cytokines and chemokines, a 1.5 to 4-fold increase in neutrophil and monocyte counts and a broad activation of innate immune genes were observed, low-antibody subjects with levels below 20 micrograms per millilitre typically showed minimal changes except when their levels rose above 20 micrograms per millilitre after repeated dosing, mild-to-moderate infusion-related reactions occurred in subjects with antibody at or above 20 micrograms per millilitre, and premedications alleviated some of the infusion-related reactions but also inhibited cytokine responses. Condition category: biomarker_context nutrient_topic: Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. plain_language: Below a certain antibody level almost nothing happened; above it, the drug worked and also caused the infusion reactions. organism: Human tissue_or_cell_type: Peripheral blood experimental_model: Single and multiple intravenous infusions in healthy volunteers stratified by pre-treatment antibody level, with and without premedication limitations: Healthy volunteers and pharmacodynamic endpoints only. Nothing here measures a tumour outcome, so the antibody strata are not validated treatment-selection thresholds. exposure: Imprime PGG 4 milligrams per kilogram intravenously, with antihistamine and corticosteroid premedication in some subjects evidence_span: {"source_cache": "artifacts/glucan-research/30988115.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "bd9bd1b314472b30b2e3513ecb5e048178de145217473fa87379e0977d21f90d", "start_char": 0, "end_char": 1787, "text_sha256": "bd9bd1b314472b30b2e3513ecb5e048178de145217473fa87379e0977d21f90d"} [bg-p30988115] Immune Pharmacodynamic Responses of the Novel Cancer Immunotherapeutic Imprime PGG in Healthy Volunteers. (2019). https://pubmed.ncbi.nlm.nih.gov/30988115/ DOI: 10.4049/jimmunol.1801533
Complete structured claim and evidence
Imprime-induced anti-cancer functionality is dependent on immune complex formation with naturally-occurring anti-beta glucan antibodies, the formation of Imprime-antibody complexes activates complement primarily via the classical complement pathway and is opsonised by iC3b, immune complex binding depends upon Complement Receptor 3 and Fc gamma Receptor IIa eliciting phenotypic activation of and enhanced chemokine production by neutrophils and monocytes enabling these effector cells to kill antibody-opsonized tumour cells, and importantly these innate immune cell changes were not evident in subjects with low antibody levels but could be rescued with exogenous antibody supplementation.
Naturally occurring anti-beta-glucan IgG antibodies → Imprime PGG / BTH1677, a soluble yeast beta-(1->3)/(1->6)-glucan source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/glucan-research/27812183.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "949fc5939bec2e3fab259b6b6161fba8cdd7779c7efa0261a1e7dbf1cab111cf", "start_char": 0, "end_char": 1493, "text_sha256": "949fc5939bec2e3fab259b6b6161fba8cdd7779c7efa0261a1e7dbf1cab111cf"}
experimental_model
Whole blood from healthy human subjects with antibody-depleted and antibody-supplemented conditions
exposure
Imprime PGG in whole blood across a range of naturally occurring anti-beta-glucan antibody levels
limitations
Ex vivo whole blood rather than treated patients. The antibody dependence is demonstrated both by absence in low-antibody donors and by rescue with added antibody.
nutrient_topic
Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. · Beta-glucan
organism
Human
plain_language
This soluble glucan does nothing on its own; it has to be caught by an antibody the person already had.
primary_references
[bg-p27812183] Imprime PGG-Mediated Anti-Cancer Immune Activation Requires Immune Complex Formation. (2016). https://pubmed.ncbi.nlm.nih.gov/27812183/ DOI: 10.1371/journal.pone.0165909
tissue_or_cell_type
Whole blood, neutrophil and monocyte
Beta-glucan: a structural family rather than an agent, what decides whether a bound glucan actually signals, the complement route that a cereal and a yeast preparation share, and the unequal human evidence behind each (2026-09-22) · lines 268–279
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Whole blood from healthy human subjects with antibody-depleted and antibody-supplemented conditions · source_derived_draft · unverified_draft
### bg-imprime-needs-an-antibody-first Imprime-induced anti-cancer functionality is dependent on immune complex formation with naturally-occurring anti-beta glucan antibodies, the formation of Imprime-antibody complexes activates complement primarily via the classical complement pathway and is opsonised by iC3b, immune complex binding depends upon Complement Receptor 3 and Fc gamma Receptor IIa eliciting phenotypic activation of and enhanced chemokine production by neutrophils and monocytes enabling these effector cells to kill antibody-opsonized tumour cells, and importantly these innate immune cell changes were not evident in subjects with low antibody levels but could be rescued with exogenous antibody supplementation. Condition category: normal nutrient_topic: Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. plain_language: This soluble glucan does nothing on its own; it has to be caught by an antibody the person already had. organism: Human tissue_or_cell_type: Whole blood, neutrophil and monocyte experimental_model: Whole blood from healthy human subjects with antibody-depleted and antibody-supplemented conditions limitations: Ex vivo whole blood rather than treated patients. The antibody dependence is demonstrated both by absence in low-antibody donors and by rescue with added antibody. exposure: Imprime PGG in whole blood across a range of naturally occurring anti-beta-glucan antibody levels evidence_span: {"source_cache": "artifacts/glucan-research/27812183.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "949fc5939bec2e3fab259b6b6161fba8cdd7779c7efa0261a1e7dbf1cab111cf", "start_char": 0, "end_char": 1493, "text_sha256": "949fc5939bec2e3fab259b6b6161fba8cdd7779c7efa0261a1e7dbf1cab111cf"} [bg-p27812183] Imprime PGG-Mediated Anti-Cancer Immune Activation Requires Immune Complex Formation. (2016). https://pubmed.ncbi.nlm.nih.gov/27812183/ DOI: 10.1371/journal.pone.0165909
Complete structured claim and evidence

The events it takes part in

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Situations it appears in

Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

Open hypotheses

Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.

This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

The classical complement pathway