{"id":"8bfb7b72-66a4-5192-822d-c1056c8e0294","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-abs-if-antibody-blocking","predicate":"inhibits","statement":"Type I antibodies from pernicious-anemia sera blocked radiocobalamin binding when mixed with intrinsic factor before the vitamin, whereas prior IF-B12 formation prevented this blocking effect.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"31107fdc-a3a6-5bf6-8b0f-54b2a2fc6bf8","mechanism_event_label":"Some antibodies stop intrinsic factor from loading B12.","subject":{"id":"035bf373-f6b9-5a96-8f08-9b54360c6105","slug":"human-if-type-i-autoantibodies","display_name":"Human type I intrinsic-factor blocking autoantibodies","entity_type_key":"protein_family"},"object":{"id":"57dd611e-efa2-597d-9d58-4e1fe9cf3234","slug":"if-cobalamin-binding-function","display_name":"Human intrinsic factor cobalamin-binding function","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"31107fdc-a3a6-5bf6-8b0f-54b2a2fc6bf8","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-abs-if-antibody-blocking-event","event_type":"biochemical_relationship","label":"Some antibodies stop intrinsic factor from loading B12.","description":"Type I antibodies from pernicious-anemia sera blocked radiocobalamin binding when mixed with intrinsic factor before the vitamin, whereas prior IF-B12 formation prevented this blocking effect.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"b6d9b937-895d-5e0a-8cc5-0454a0b7d373","slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"},"role":"nutrient","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"490161eb-b7f8-56b6-82bc-77c8c0bdc1ca","slug":"gif","display_name":"Human gastric intrinsic factor / GIF","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"035bf373-f6b9-5a96-8f08-9b54360c6105","slug":"human-if-type-i-autoantibodies","display_name":"Human type I intrinsic-factor blocking autoantibodies","entity_type_key":"protein_family"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"57dd611e-efa2-597d-9d58-4e1fe9cf3234","slug":"if-cobalamin-binding-function","display_name":"Human intrinsic factor cobalamin-binding function","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human pernicious-anemia sera; ordered-addition binding assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"IF plus type I antibody followed by radioactive B12 versus IF-B12 formed first","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Sera cohort contained 79 patients; the abstract does not give functional-assay subset size. This is not every mechanism of autoimmune gastritis.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Some antibodies stop intrinsic factor from loading B12.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[schade-1967-if-antibody] Studies on antibody to intrinsic factor. (1967). https://pubmed.ncbi.nlm.nih.gov/6021209/ DOI: 10.1172/jci105563","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human gastric intrinsic factor binding system","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"63baa1b7-3c97-55be-8554-314733f7c429","evidence_kind":"source_excerpt","locator":"Lines 504-515","start_line":504,"end_line":515,"excerpt":"### b12-abs-if-antibody-blocking\nType I antibodies from pernicious-anemia sera blocked radiocobalamin binding when mixed with intrinsic factor before the vitamin, whereas prior IF-B12 formation prevented this blocking effect.\nCondition category: machinery_impairment\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Some antibodies stop intrinsic factor from loading B12.\norganism: Homo sapiens\ntissue_or_cell_type: Human gastric intrinsic factor binding system\nexperimental_model: Human pernicious-anemia sera; ordered-addition binding assays\nlimitations: Sera cohort contained 79 patients; the abstract does not give functional-assay subset size. This is not every mechanism of autoimmune gastritis.\nexposure: IF plus type I antibody followed by radioactive B12 versus IF-B12 formed first\ncross_nutrient: false\n[schade-1967-if-antibody] Studies on antibody to intrinsic factor. (1967). https://pubmed.ncbi.nlm.nih.gov/6021209/ DOI: 10.1172/jci105563","model_system":"Human pernicious-anemia sera; ordered-addition binding assays","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [schade-1967-if-antibody] Studies on antibody to intrinsic factor. (1967). https://pubmed.ncbi.nlm.nih.gov/6021209/ DOI: 10.1172/jci105563","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"73145023-2982-5848-aff2-8d8875d6b9c5","stable_key":"import-7fc92b9e-9cbf-556e-8719-6b5244625250","title":"Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"ad5b3a51d36e856aa7fdfd1cc23f690b094689bad87d28e1a621a54675a01c92","revision_id":"118bd616-0c13-549f-bfeb-bc439715b89c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}