Antigen Presenting Cells Begin the Immune Response

An immune response is a specific sequence of events. One of the first cell types to respond to an antigen is the macrophage. These scavenger cells alert lymphocytes by displaying antigens from engulfed invaders. Each such foreign antigen is attached to the macrophage surface by

Blood transport

Lymph /node

-T cell

Blood transport

B cell

B cell

(4) Both T cells and B cells are transported through the blood to lymphatic organs, such as the lymph nodes, ducts, and spleen.

Figure 16.17

Scanning electron micrograph of a human circulating lymphocyte (8,600x).

Figure 16.17

Scanning electron micrograph of a human circulating lymphocyte (8,600x).

Shier-Butler-Lewis: I IV. Transport I 16. Lymphatic System and I I © The McGraw-Hill

Human Anatomy and Immunity Companies, 2001

Physiology, Ninth Edition a self protein that is encoded by a gene that is part of a cluster of proteins called the major histocompatibility complex (MHC). In this way the macrophage can display the foreign antigen, but be recognized as self by the T cell.

Displaying the foreign antigens, macrophages migrate to the nearest lymph nodes where they encounter many varieties of T and B cells. T cell recognition of and binding to the antigen-presenting cell begins a chain reaction of events and effects.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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