Immunology: How is external antigen shown?

This simplified antigen-presentation lesson follows external protein uptake, processing into peptides, display with MHC class II and CD4-associated helper T-cell recognition. The T-cell receptor recognises the peptide–MHC combination; CD4 supports interaction with MHC II. Recognition is only one step: the video does not show the full requirements for T-cell activation. Original silent 36-second lesson. Silent caption-led lesson; no narration or music. Original AI-assisted diagrams; AI source review 16 October 2026, not clinician certification. Sources: https://openstax.org/books/anatomy-and-physiology-2e/pages/21-2-barrier-defenses-and-the-innate-immune-response https://openstax.org/books/anatomy-and-physiology-2e/pages/21-3-the-adaptive-immune-response-t-lymphocytes-and-their-functional-types https://openstax.org/books/anatomy-and-physiology-2e/pages/21-4-the-adaptive-immune-response-b-lymphocytes-and-antibodies Create a review prompt: https://meyshan.com/app/recall?utm_source=meyshantube&utm_medium=video&utm_campaign=student_daily_202610&utm_content=d11_c Transcript: on-screen text from this silent video; no spoken narration.