Specific Immune Defenses: Overview

<h1>Text Preview</h1> <p>Until recently, chickenpox was a common childhood illness. Chickenpox is caused by the varicella-zoster virus, which produces a blister-like rash on the skin and mucous membranes. Chickenpox is easily spread from one child to another. Therefore, when a child is infected, parents often notify the parents of other kids he's been in contact with to find out if they've already had the disease.</p> <p>The good news is once you've had chickenpox, you aren't very likely to get it again. That’s because of the body’s specific immune responses to the virus. Let's look at how our immune system reacts when we're exposed to chickenpox.</p> <p>The chickenpox virus is spread through direct contact or through the air. The disease is highly contagious, which means the virus easily gets past the body’s first line of immune defense—the mucous membranes in the mouth and nose. Once it enters the body, the virus infects cells and makes many new viral particles. Circulating macrophages, part of the second line of immune defense, engulf and destroy some of the viruses. This is where the third line of defense —the specific immune response—takes over.</p> <p>The body's specific immune response has three components: T cells, B cells, and antibodies. T cells and B cells are two types of white blood cells, or lymphocytes. Lymphocytes recognize and respond to particular foreign molecules called antigens. Antibodies are antigen-binding proteins involved in the immune response. They are secreted by certain B cells. T cells, B cells, and antibodies work together to defend against all types of pathogens. Macrophages, part of the body's nonspecific immune defense system, are also involved in the specific immune response.</p> <p>In this activity, we'll start with an overview of the key features of the specific immune response. We'll see the specific role T cells play in the cellular response, then look at the role of B cells in the humoral response. Finally, we'll look at what happens when the immune system doesn't function properly.</p> <p id="TextCopyright">Copyright 2006 The Regents of the University of California and Monterey Institute for Technology and Education</p>