Chapter 8: Host Defenses
PRINCIPLES OF HOST DEFENSES:
(1) innate (nonspecific) defenses, which protect against microorganisms in general
(2) adaptive (specific) immunity, which protects against a particular microorganism.
INNATE DEFENSES can be classified into three major categories:
(1) physical barriers, such as intact skin and mucous membranes
(2) phagocytic cells, such as neutrophils, macrophages, and natural killer cells
(3) proteins, such as complement, lysozyme, and interferon.
ADAPTIVE IMMUNITY is mediated by antibodies and T lymphocytes.
, This chapter focuses on nonspecific defenses in the early response to bacterial infection.
There are two main types of host defenses against bacteria:
1. Pyogenic (pus-producing) response:
- Which consists of antibodies, complement, and neutrophils.
Examples: Staphylococcus aureus and Streptococcus pyogenes.
- These pyogenic bacteria are often called “extracellular pathogens” because they do not
invade cells.
- Cause inflammation via antibody and complement mediated mechanisms.
2. Granulomatous response:
- Which consists of macrophages and CD-4positive (helper) T cells.
Examples: Mycobacterium tuberculosis and Listeria monocytogenes
PRINCIPLES OF HOST DEFENSES:
(1) innate (nonspecific) defenses, which protect against microorganisms in general
(2) adaptive (specific) immunity, which protects against a particular microorganism.
INNATE DEFENSES can be classified into three major categories:
(1) physical barriers, such as intact skin and mucous membranes
(2) phagocytic cells, such as neutrophils, macrophages, and natural killer cells
(3) proteins, such as complement, lysozyme, and interferon.
ADAPTIVE IMMUNITY is mediated by antibodies and T lymphocytes.
, This chapter focuses on nonspecific defenses in the early response to bacterial infection.
There are two main types of host defenses against bacteria:
1. Pyogenic (pus-producing) response:
- Which consists of antibodies, complement, and neutrophils.
Examples: Staphylococcus aureus and Streptococcus pyogenes.
- These pyogenic bacteria are often called “extracellular pathogens” because they do not
invade cells.
- Cause inflammation via antibody and complement mediated mechanisms.
2. Granulomatous response:
- Which consists of macrophages and CD-4positive (helper) T cells.
Examples: Mycobacterium tuberculosis and Listeria monocytogenes
