Advanced Course in Immunology On Demand Lecture Recordings-Anatomy of the Immune Response

Video Transcription

Video Summary

The lecture introduced the immune system as a highly mobile network of cells that must constantly solve three problems: where to go, what to do, and how to act once there. Using dramatic microscopy videos, the speaker showed neutrophils chasing and engulfing bacteria, illustrating how essential innate immune cells are for host defense.<br /><br />A major theme was leukocyte trafficking from blood into tissues. Because blood flow in microvessels is fast and physically demanding, immune cells need specialized adhesion molecules to exit circulation safely. The key process occurs mainly in post-capillary venules, where endothelial cells become “Velcro-like” during inflammation. Leukocyte recruitment follows a multistep cascade: rolling via selectins, activation by chemokines through GPCRs, and firm arrest via integrins. This mechanism is tissue-specific and can be targeted therapeutically, as in drugs for multiple sclerosis or inflammatory bowel disease.<br /><br />The lecture then shifted to T cells. Naive T cells recirculate through blood and secondary lymphoid organs to find rare antigen on dendritic cells. High endothelial venules in lymph nodes enable homing, while sphingosine-1-phosphate signaling controls exit. Once activated, T cells proliferate, become effector cells, and later form memory subsets with distinct migratory behaviors. Imaging revealed that T cell-dendritic cell interactions proceed in phases, from brief scanning to stable contact and eventually proliferation.<br /><br />Finally, the talk covered B cells and lymph-borne antigen capture by subcapsular sinus macrophages, which present intact virus to B cells and initiate antibody responses. The speaker emphasized that histology often misrepresents living cell behavior, making intravital imaging essential for understanding immune dynamics.

Asset Subtitle

Lecture 1: Ulrich H. von Andrian, Harvard Medical School and Ragon Institute of MGH, MIT and Harvard

Asset Caption

Ulrich H. von Andrian, Harvard Medical School, Ragon Institute of MGH, MIT and
Harvard Anatomy of the Immune Response

Keywords

immune system

leukocyte trafficking

neutrophils

innate immunity

post-capillary venules

selectins

chemokines

integrins

T cells

dendritic cells

high endothelial venules

sphingosine-1-phosphate

B cells

intravital imaging