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CancerQuest > Introduction to Cancer Biology > Introduction to the Immune System > Section Summary: The Immune System

Section Summary: The Immune System

Immune System Introduction

• The immune system is able to distinguish between 'self' and 'non-self' and between normal and abnormal cells.
• The immune system acts through two broad and somewhat overlapping mechanisms - Specific Immune Responses and Non-Specific (Innate) Immunity.

The Innate Immune System

• The innate immune system carries out the non-specific functions.
• The innate immune system consists of three components:
  • Physical and chemical barriers such as skin, mucus, and earwax
  • Cells including macrophages and neutrophils
  • Proteins that include enzymes found in saliva and tears
• The innate immune system recognizes  general features of potential pathogens.

The Acquired Immune Response

• The acquired immune response carries out specific or adaptive immunity.
• The adaptive response develops and changes over the course of our lifetimes.
• The adaptive immune response is highly specific for invading pathogens.
• T cells and B cells are the main cell types of the acquired immune system.
• The specific immune response is characterized by the following: 1) antigen specificity, 2) diversity, 3) memory, and 4) self:non-self discrimination.
• The adaptive immune response can detect cancer cells.

Cells of the Acquired Immune Response

• B cells and T cells are known as lymphocytes and they originate in the bone marrow.
• Lymphocytes reside in lymphatic tissue such as lymph nodes and the spleen.
• A protein or other product that can be recognized by the immune system and lead to the production of an immune response is known as an antigen.
• B cells produce antibodies that bind tightly to a pathogen which is then inactivated or destroyed.
• T cells mature into either helper T cells or cytotoxic T lymphocytes.

The Immune System and Cancer

• The immune system can recognize mutant or otherwise abnormal cells as foreign.
• Cancer cells can mutate enough so that they are able to escape the surveillance mechanisms of the immune system.
• Many cancers produce chemical signals that inhibit the actions of immune cells.
• Some tumors grow in locations such as the eyes or brain, which are not regularly patrolled by immune cells.
• Immunotherapy and cancer vaccines are designed to provide the immune system with the signals that it needs to recognize and destroy cancer cells.