Our immune system is designed to protect us from any potential pathogen that may invade our bodies. How can our bodies anticipate and defend us from pathogens? How do vaccines protect us from infection? Antibodies are proteins that can recognize viruses and bacteria and help the body to fight infection. Like all proteins, antibodies are encoded in the DNA of our cells. The B cells in our body can generate 100,000,000,000 different antibodies capable of recognizing any type of pathogen that might invade our body. If the human genome only consists of 30,000 genes, how can we get this many different antibodies? This module will address these questions and will familiarize students with the following concepts from the North Carolina Standards of Competency: the immune response, genetics, cell specialization, and communication among cells in an organism.

Teacher's Guide

Intro to the Immune System

This module introduces the Immune System and how it functions to protect us from pathogenic microbes that can cause disease. Specifically, students will learn about the two major “arms” of the Immune System – the cell-mediated response (which involves cells called macrophages and neutrophils) and the humoral response (which destroys pathogens through special proteins called antibodies).

The Exciting World of Antibodies

Antibodies are special proteins made by B-cells that can recognize and bind to invading pathogens in our bodies. They protect us in several ways including 1) by preventing pathogens from binding to our cells, and 2) helping other immune cells recognize and kill pathogens. In this video, antibody structure and function is demonstrated by using colored gloves and balloons.

So many pathogens, so little time

Our antibodies are important for keeping us healthy and our DNA plays a key role in this. There are millions (if not billions) of different microbes that we come into contact with, however we only have 30,000 genes. How do we generate enough unique antibody proteins to recognize and neutralize all of these pathogens? The answer is through a unique genetic process called VDJ recombination. Through recombining a small number of genes into new patterns, our bodies can generate millions of unique antibodies. This process is explained in detail in this module. To reinforce the concept of VDJ recombination, students participate in a hands-on “pathogen vs B-cell” activity.

Clonal Expansion and Memory Response

Following an infection, our immune system quickly goes to work and specific antibodies can recognize the invading pathogen. Once a match is made, the B-cells producing antibodies specific for that pathogen begin to make many identical copies of themselves through a process called “clonal expansion”. This ensures that there are enough B-cells to clear the infection. After clonal expansion, some B cells turn into a special type of cell called a “Memory B Cell” that remains in your body for years and can respond quickly if you ever encounter that pathogen again. This is why many diseases (like chicken pox) cannot infect the same person twice.

How Vaccines Work

Some infectious pathogens are very dangerous and could be harmful even if we were infected just once. Luckily, we have vaccines which allow our bodies to make Memory B Cells for that pathogen without having to actually get sick. There are several types of vaccines which will be discussed in detail in this module, but all of these have been instrumental in limiting (and in some cases even eliminating) very harmful diseases.