faculty of biotechnology and life science

ADAPTIVE IMMUNE

RESPONSE TO

EXTRACELLULAR BACTERIA

Group Members

DAYANA ‘AMIRAH BT.DARUS 4081017391

MANIZHEH KHALIPOUR FARSHBAFI 4081022241

MOHAMED ALI MOHAMUD 4072012671

NORMAZATULIZMA MOHAMAD 4081023341

NOR FARIDAH MOHD SAID 4081028481

RASYIDAH MISWANDI 4081025401

ROSLINA JAMALUDIN 4081021941

Immune system

Adaptive immune response

B cell

Effector functions of antibodies

Neutralization of microbes and their toxins by binding to their surface and neutralize it by blocking their active sites.

Opsonization of microbes (binding to Fc receptors on phagocytes; at the same time, stimulation of microbicidal activities of phagocytes) and also tagging the pathogen.

Activation of the complement system both IgG and IgM trigger the complement system which results in cell lysis and inflammation.

White Blood CellsLeukocytes

(White Blood Cells)

lymphocytesOther Types of

WBC

Eosinophils MacrophagesT cells NK CellsB Cells

Helper T cells- secrete lymphokines that direct B cells into producing antibodies and also direct the Killer T cells as to which cell they get to eliminate.

Killer T cells- They find specifically coded infected cells, and then destroy them with cytotoxins. They may be directed by Helper T cells

Suppressor T cells- in charge of slowing and stopping the immune response after the foreign substance is destroyed.

Memory T cells- derived from Helper T cells, have the same properties as their parent cell, and circulates until the body encounters the pathogen its parent cells were designer for.

T T CELLS !!CELLS !!

T Cells Activation

II. Second Line of Defense1. Phagocytosis: Derived from the Greek words “Eat and

cell”. Phagocytosis is carried out by white blood

cells: macrophages, neutrophils, and occasionally eosinophils.

Neutrophils predominate early in infection. Wandering macrophages: Originate from

monocytes that leave blood and enter infected tissue, and develop into phagocytic cells.

Fixed Macrophages (Histiocytes): Located in liver, nervous system, lungs, lymph nodes, bone marrow, and several other tissues.

Phagocytic Cells: Macrophages (Monocytes), Neutrophils, and

Eosinophils

(Macrophages)

Stages of Phagocytosis1. Chemotaxis: Phagocytes are

chemically attracted to site of infection.2. Adherence: Phagocyte plasma

membrane attaches to surface of pathogen or foreign material. Adherence can be inhibited by capsules

(S. pneumoniae) or M protein (S. pyogenes).

Opsonization: Coating process with opsonins that facilitates attachment. Opsonins include antibodies and

complement proteins.

Phagocytes are Attracted to Site of Infection by

Chemotaxis

Stages of Phagocytosis (Continued)

3. Ingestion: Plasma membrane of phagocytes extends projections (pseudopods) which engulf the microbe. Microbe is enclosed in a sac called phagosome.

4. Digestion: Inside the cell, phagosome fuses with lysosome to form a phagolysosome. Lysosomal enzymes kill most bacteria within 30 minutes and include: Lysozyme: Destroys cell wall peptidoglycan Lipases and Proteases RNAses and DNAses

After digestion, residual body with undigestable material is discharged.

Process of Phagocytosis

Conclusions

The most common disease-causing microbes are bacteria, viruses, and protozoa. Each uses a different tactic to infect a person, and, therefore, each is thwarted by different components of the immune system.

Virus Protozoa Bacteria

There are two mains sites where pathogens may reside: extracellular in tissue spaces or intracellular within a host cell, and the immune system has different ways of dealing with pathogens at these sites.

Most bacteria live in the spaces between cells and are readily attacked by antibodies.

Antibodies are the primary defense against extracellular pathogens. When antibodies attach to a bacterium; they send signals to complement proteins and phagocytic cells to destroy the bound microbes.

Some bacteria are eaten directly by phagocytes, which signal to certain T cells to join the attack.

Summary:

Macrophages are able to launch the first strike…

more help is needed to overcome rapidly reproducing invaders…

Help from the ADAPTIVE IMMUNE System results in a coordinated successful defense !

Major players the B lymphocytes

THANK YOU ……..