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Chapter 11: Innate immunity Cheat Sheet by

study guide for MCB2010C

Overview of Immune System

An immune response, coordi­nated by the immune system, aims to eliminate antigens through antibody genera­tion.
The immune system consists of innate and adaptive branches with common features: Recogn­ition of diverse pathogens Elimin­ation of identified invaders Discri­min­ation between self and foreign antigens
Innate immunity is non-sp­ecific and ancient, found in all eukaryotic organisms.
Adaptive immunity, unique to verteb­rates, matures over time, tailors responses, and exhibits memory.
Microbiota play a crucial role in shaping and regulating immune responses.


Abnormally high body temper­ature induced by pyrogens.
Enhances antiviral effects, phagocyte effici­ency, leukocyte produc­tion, limits pathogen growth, and promotes tissue repair.
Low-grade fever (37.5°C to 38.3°C) is protec­tive; high fever (40.5°C) is life-t­hre­atening

Blood Components and Leukocytes

Blood Compos­ition - Erythr­ocytes transport oxygen, platelets stem blood loss, leukocytes are crucial for the immune system. Leukoc­ytes: granul­ocytes (visible granules) and agranu­locytes (lack granules).
Leukocyte Activation Activated leukocytes release molecules for diverse functions. These molecules have diverse functions, including recruiting other leukoc­ytes, restri­cting pathogen growth, triggering fever, and stimul­ating inflam­mation

Microbial Impact on Immunity

Changes in normal microbiota can confuse the immune system, linked to allergies and autoimmune diseases.
Hygiene Hypothesis suggests reduced microbial diversity hinders immune responses.

Mechanical and Chemical Barriers

Mechanical barriers (e.g., skin, tears, urine) hinder pathogen entry. Chemical barriers combat invaders (e.g., lysozyme, stomach acidity)
Antimi­crobial peptides (AMPs) like defensins target pathogens by inserting into cell membranes.

The Plague

Signs and Symptoms: Fever, chills, weakness, abdominal pain, diarrhea, vomiting, bleeding, shock, tissue death.
Plague Doctors Distin­ctive attire: beaked mask, cane, long coat, gloves, hat. Protection against bacter­ia-­laden secretions and aerosol droplets.
Mortality Historical impact with devast­ating outbreaks (Plague of Justinian, Black Plague, Great Plague of London, Third Pandemic).

Types of Leukocytes

Neutro­phils: Most abundant, engage in phagoc­ytosis. Eosino­phils: Combat parasitic infections and allergic responses. Basophils: Involved in allergic responses and combat parasitic infect­ions. Mast Cells: Release histamine, contribute to allergic responses and parasitic defense. Monocytes: Mature into macrop­hages, involved in chronic infect­ions, inflam­mation, autoimmune disorders, and cancers. Macrop­hages: Highly phagoc­ytic, destroy a wide range of pathogens, serve as antige­n-p­res­enting cells.

Blood and Lymphatic System

Blood delivers plasma to tissues, forming inters­titial fluid
Lymphatic system collects and filters lymph (fluid), screening for pathogens in lymph nodes
Primary lymphoid tissues (thymus, bone marrow) produce and mature leukoc­ytes.
Secondary lymphoid tissues (nodes, spleen, MALT) filter lymph

Yersinia pestis and Immune System

Infection Encounter Yersinia pestis faces non-sp­ecific immune defenses and leukoc­ytes.
Evasion Strategies Counte­racting defenses, reducing phagoc­ytosis, producing a protective capsule, using inject­osomes. Plasmids generate proteins suppre­ssing lymphocyte chemot­axis.

Immune Evasion Strategies of Yersinia pestis

Subverts macrop­hages, impairs inflam­matory response, targets natural killer cells, produces proteases.

Natural Killer Cells

Abundant in the liver, provide innate protection against viruses, bacteria, parasites, and tumor cells.

Treatment and Mortality of the Plague

Intrav­enous antibi­otics (genta­micin, ciprof­lox­acin) recomm­ended for Yersinia pestis.

Inflam­matory Response

Inflam­mation is essential for innate immunity and healing.
Three phases: vascular changes, leukocyte recrui­tment, resolu­tion.
Chronic inflam­mation exacer­bates tissue injury and promotes diseases


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