This document summarizes immunity to microbes, including both innate and adaptive immunity. It discusses extracellular bacteria that can replicate outside of cells, such as Staphylococcus aureus and Streptococcus pneumoniae, and the innate immune response of complement activation and phagocytosis. Intracellular bacteria like Mycobacterium tuberculosis that can survive inside cells require a cell-mediated adaptive immune response. The document also covers topics like adaptive humoral and cellular immunity, superantigen activation of T cells, mechanisms of bacterial evasion of the immune system, and the roles of macrophages and cytokines in responses to intracellular microbes.

1. Immunity to Microbes
Fadel Muhammad Garishah
Infection and Immunity
Faculty of Medicine Diponegoro University

2. How do you describe this?
Microbe
Neutrophile
PMN Cell

3. General features
• Defense against microbes via innate and adaptive
immunity
• Responds in distinct and specialized ways to
different types of microbes
• survival and pathogenicity of microbes influenced
by the ability of the microbes to evade or resist
the immunity
• tissue injury and disease may be caused by the
host response to the microbe and its products
rather than by the microbe itself.

4. Microbes
• Prion
• Viruses
• Bacteria
• Parasites

5. Immunity to Extracellular Bateria

6. Extracellular Pathogenic Bacteria
Extracellular bacteria Human Diseases Pathogenicity
Staphylococcus aureus Skin/soft tissue infection, lung
abscess, Systemic: toxic shock
syndrome, food poisoning
Enterotoxin superantigen
induced
Streptococcus
pyogenes Group A
Pharyngitis, Skin impetigo;Cellulitis,
Scarlet fever (rheumatic fever)
Streptolysin-0
Streptococcus
pneumonia
Pneumonia, Pneumococcus
meningitis
Pneumolysin, Capsule
Escherichia coli UTI, Genteritis, Septic shock LPS Endotoxin
Vibrio cholerae Diarrhea cholerae Cholera toxin (cAMP
increases)
Clostridium tetani Tetanus Tetanus toxin
Neisseria meningitidis Meningococcus meningitis Endotoxin
Corynebacterium
diphtheriae
Diphtheria Diphtheria toxin

7. The extracellular bacteria
• Extracellular bacteria defined as the bacteria
that capable to replicate outside the host
cells, e.g. in blood, connective tissue,
airway/gastrointestinal tract
• The bacteria may either 1) induce
inflammation or 2) produce toxins that
destruct the body tissue
• E.g. of toxin: Endotoxin of gram-negative or
lipopolysaccharide (LPS).

8. Innate immunity to extracellular
bacteria
• Principles: complement activation,
phagocytosis and inflammatory response.
• Complement activation
• Activation of phagocytes and inflammatory
response

9. Adaptive immunity to extracellular
bacteria
• Humoral immunity: block infection, eliminate
microbes and neutralize toxins
• CD4+ produces cytokines that induce local
inflammation and activate phagocytic function
and microbicidal activities of Macrophages
and Neutrophiles

10. Humoral Immunity

11. Cellular Immunity

12. Polyclonal activation of T cells by
bacterial superantigens

13. Extracellular bacteria evasion
• A mechanism used by bacteria to evade
humoral immunity.
• Genetic variation of surface antigen (E. coli, N.
gonorrhoeae, S. typhimurium)
• Resistance to phagocytes (Pneumococcus)
• Destruction to ROS (Catalase producing
Staphylococci)

14. Immunity to
Intracellular Bacteria

15. Intracellular bacteria
• A characteristic of facultative intracellular
bacteria is their ability to survive even
replicate within phagocytes.
• Requires cell-mediated immunity

16. Intracellular bacteria
Microbe Human Diseases Pathogenicity
Mycobacteria species Tuberculosis, Leprosy Macrophage activation,
granulomatous
inflammation, tissue
destruction
Listeria monocytogenes Listeriosis Listeriolysin damages cell
membrane
Legionella pneumophila Legionnaires’ disease Cytotoxin lyses cells

17. Innate and Adaptive Immunity
• The innate immune response to intracellular
bacteria consists mainly of phagocytes and NK
(natural killer) cells.
• The major adaptive-protective immune
response against intracellular bacteria is cell-
mediated immunity
• The macrophage activation in response to
intracellular microbes is capable of causing
tissue injury

21. Figure 15-5 Naive CD4+ T lymphocytes may differentiate into TH1 cells, which activate
phagocytes to kill ingested microbes, and TH2 cells, which inhibit macrophage activation.
The balance between these two subsets may influence the outcome of infections, as
illustrated by Leishmania infection in mice and leprosy in humans.

22. Mechanisms of Immune Evasion by
Bacteria
• Inhibition of phagolysosome formation
(Mycobacterium tuberculosis, Legionella
pneumophila)
• Inactivating reactive oxygen and nitrogen
intermediates Mycobacterium leprae
(phenolic glycolipid)
• Disruption of phagosome membrane, escape
into cytoplasm Listeria monocytogenes
(hemolysin protein)