INNATE IMMUNE SYSTEM

Presented By: Ayesha Aftab Zainab Nooruddin

Dept. of BioinformaticsMohammad Ali Jinnah University.

Innate Immune System

Second Line of Defense

First Line of Defense

PhysicalBarriersPhysicalBarriers

ChemicalBarriers

ChemicalBarriers

Skin

Mucous

CELLS PROTEINS

Macrophages

Neutrophills

Phagocytes

NK CellsDendritic

Cells

Monoocytes

Complement

Toll-Like

INNATE IMMUNITY

☻ Innate immune system refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body

☻ Natural immunity

FIRST LINE of DEFENSE

☻ It stops the microbe from entering into our body

☻ The skin and mucous membranes☻ Normal Body Flora: They help to protect a

host from becoming infected with more harmful micro-organisms by acting as a physical barrier

SECOND LINE of DEFENSE

☻ If microbes do manage to get inside the body then the second line of defense is activated

☻ This includes the working of different type of cells and proteins

PHAGOCYTES

☻ From the Greek phagas, to eat, and kutos, a vessel (or cell)

☻ Recognition of a microbial invader

☻ Quickly followed by its engulfment

MONOCYTES

☻ Monocytes develop in the bone marrow and reach maturity in the blood. 

☻ Large, smooth, lobed nuclei ☻ Abundant cytoplasm that contains granules. ☻ Ingest foreign or dangerous substances  ☻ Present antigens to other cells☻ Monocytes leave the blood stream after 20–40 hours☻ Transform into macrophages or dendritic cells

MACROPHAGES

☻ Macrophages - large eaters are the sentries of the immune system

☻ Produced by stem cells in the bone marrow

☻ Distributed throughout the body just below the surface of the skin and mucous membranes

☻ In their normal, resting state, macrophages are the janitors of the body

☻ During this stage, macrophages proliferate slowly

DENDRITIC CELLS

☻ Specialized antigen-presenting cells

☻ Long outgrowths called dendrites☻ Engulf microbes ☻ Present in skin☻ The inner lining of the nose☻ The lungs☻ The stomach☻ The intestines☻ Migrate to the lymphoid tissues

where they interact with T and B cells to initiate the adaptive immune response

NEUTROPHILLS

☻ Neutrophils make up the majority of white blood cells in the body

☻ Their sole job is to respond to the site of an infection in order to attack and eat invaders

☻ Are present in the bloodstream☻ Neutrophils respond to the

location of infection and inflammation after detecting chemical signals in the blood

☻ Short lived☻ Dead neutrophils make up a

large proportion of puss

NATURAL KILLER CELLS

☻ Natural killer cells are called “natural” killers because they are ready to kill as soon as they are formed

☻ Natural killer cells recognize and attach to infected cells or cancer cells, then release enzymes and other substances that damage the outer membranes of these cells

☻ Natural killer cells are important in the initial defense against viral infections

☻ Also, natural killer cells produce cytokines that regulate some of the functions of T cells, B cells, and macrophages

COMPLEMENTS PROTEINS

☻ The complement system consists of more than 30 proteins that act in a sequence: One protein activates another and so on. This sequence is called the complement cascade.

☻ Complement proteins have many functions in acquired immunity as well as innate:

☻ Killing bacteria directly☻ Helping destroy bacteria by attaching to them and thus making the

bacteria easier for neutrophils and macrophages to identify and ingest☻ Attracting macrophages and neutrophils to a trouble spot☻ Neutralizing viruses☻ Helping immune cells remember specific invaders☻ Promoting antibody formation☻ Enhancing the effectiveness of antibodies☻ Helping the body eliminate dead cells and immune complexes (which

consist of an antibody attached to an antigen)

TOLL-LIKE RECEPTORS

☻ Toll-like receptors (TLRs) are a class of proteins

☻ They are usually expressed in cells such as macrophages and dendritic cells

☻ Once these microbes have breached physical barriers they are recognized by TLRs, which activate immune cell responses

REFERENCES

☻ http://www.microbiologyonline.org.uk/about-microbiology/microbes-and-the-human-body/immune-system

☻ http://www.novimmune.com/science/innate.html☻ http://www.merckmanuals.com/home/immune-disorders/biology-

of-the-immune-system/innate-immunity☻ http://www.biology.arizona.edu/immunology/tutorials/

immunology/page3.html☻ http://www.ncbi.nlm.nih.gov/books/NBK26846/☻ http://www.immunologyexplained.co.uk/HowItWorks.aspx