INNATE IMMUNITY

Presented By:

Preety Sweta Hembrom

Subject- Immunology

M.Sc. Genomic Science

Central University Of Kerala

IMMUNE SYSTEM

The immune system is a system of biological structures and processes within an organism and protects against attacks by foreign invaders.

These invaders are primarily microbes.

The human body provides an ideal environment for many microbes.

IMMUNITY:

Immunity is the state of having sufficient biological defenses to avoid infection, diseases or other unwanted biological invasion.

It is the capability of the body to resist harmful microbes from entering it.

Immunity involves both specific and non-specific components.

CONTD…

The mechanism of immunity can be achieved by two types of immune response:

1. Cell- mediated immune response

2. Humoral immune response

COMPONENTS OF IMMUNITY:

Contains two major components:

1. Innate Immunity (Non-specific)

2. Adaptive Immunity (Specific)

Innate Immunity

INNATE IMMUNITY:

The innate immune system, also known as non-specific immune system.

Innate immune systems provide immediate defense against infection, and are found in all classes of plant and animal life.

DEFENSIVE BARRIERS OF INNATE IMMUNITY:

Innate Immune system

First line Second line1) Anatomic barriers A) cells

2) Chemical & biochemical inhibitors 1- Natural killer

3) Normal flora 2- Phagocytes

B) Soluble factors

C) Inflammatory

barriers

FIRST LINE:1) Anatomic barriers: Intact skin Mucous coat Mucous secretion Blinking reflex and tears The hair at the nares Coughing and sneezing reflex

CONTD:2) Chemical & biochemical inhibitors Sweat and sebaceous secretion Hydrolytic enzymes in saliva HCl of the stomach Proteolytic enzyme in small intestine Lysozyme in tears Acidic pH in the adult vagina

CONTD:3) Normal bacterial flora: Competition for essential nutrients

Production of inhibitory substances

SECOND LINE:

1. CELLS:

a) Natural Killer Cells (NK):

 Effectors of innate immunity  Cytotoxic lymphocyte  Differentiate and mature in the bone

marrow, lymph node, spleen, tonsils and thymus.

FUNCTIONS: Cytolytic Granule Mediated Cell Apoptosis.

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC).

Cytokine induced NK and CTL activation

Tumor cell surveillance

Immune System - Natural Killer Cell.mp4

CONTD:

b) Phagocytes:

Cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.

 The professional phagocytes include cells called neutrophils, monocytes, macrophages, dendritic cells, and mast cells.

PHAGOCYTOSIS:

Elle Mechnikov was the first to observe phagocytosis by white blood cells.

I. Chemo taxis & attachment:

a- Attraction by chemo tactic substances

(microbes, damaged tissues)

b- Attachment by receptors( such as TLRs ) on surfaces of phagocytes.

CONTD:

II. Ingestion:

* Phagocyte pseudopodia surround organism forming phagosome.

* Opsonin and co-factors enhance phagocytosis.

* Fusion with phagocyte granules and release digestive, toxic contents

CONTD:

III. Killing :

Digestion and killing by Lysozyme.

2. SOLUBLE FACTORS:

Acute phase protein (Plasma protein, CRP=C reactive protein, Fibrin.)

Complement (proteins in serum, body fluids)

Interferon (Proteins against viral infections)

Properdin (Complement activation) Lactoferrrin, Transferrin (Iron binding

protein) Lactoperoxidase (Saliva & Milk) Lysozyme (Hydrolyze cell wall)

3. INFLAMMATORY BARRIERS: Tissue damage caused by a wound or by an

invading pathogenic microorganism induces a complex sequence of events collectively known as Inflammatory response.

 Inflammation is stimulated by chemical factors released by injured cells and serves to establish a physical barrier against the spread of infection, and to promote healing of any damaged tissue following the clearance of pathogens.

Chemical factors produced during inflammation are histamine, bradykinin, serotonin, leukotrienes, and prostaglandins.

The Inflammatory Response.mp4