Applied Molecular Immunology

Question 1

10 major human pathogens

Answer 1

Bacteria
Extracellular
Intracellular
Viruses
Fungi
Yeast
Moulds
Parasites
Protozoa
Helminths

Question 2

Function of the innate immunity

Answer 2

To act as the first line of defense against pathogens. Either eliminating the pathogens or slowing them down to give the adaptive immune system time to be activated

Question 2

Two tpes of pathogen immunity in humans

Answer 2

Innate and Adaptive

Question 3

Give 5 components of the innate immune system

Answer 3

Epithelial layers
Mucus
Macrophages
Neutrophils
The complement system

Question 4

Which cells act as a bridge between the innate and adaptive immunity

Answer 4

Dendritic cells and Macrophages

Question 5

What do the antigen presenting cells do?

Answer 5

They take up the pathogenic antigen and present them on their cell surface, usually in conjunction with the Major Histocompatibility Complex.
This helps to recruit and activate the appropriate T and/or B cells to respond and secrete cytokines for that specific antigen.

Question 6

What is the humoral immune response

Answer 6

AKA antibody mediated destruction.
Characterized by production of antigen-specific antibodies and complement mediated mechanisms to eliminate small extracellular pathogens either directly or by phagocytic destruction.
Targets extracellular pathogens.

Question 7

What is cell mediated immunity

Answer 7

Characterized by the secretion of various cytokines and cytolytic mechanisms by cells like the Natural killer cells and certain T cells.
Targets mainly intracellular pathogens

The T cells are produced through the differentiation of the immature T cells by cytokines produced during the innate immune response

Question 8

What are the 5 basic mechanisms of adaptive immunity against bacterial infections?

Answer 8

The neutralization of bacterial toxins or enzymes by antibodies
The killing of bacteria by antibody mediated complement activation
The opsonization of bacteria by antibodies (with or without complement components) followed by their phagocytosis and destruction.
The destruction of intracellular bacteria by activated macrophages
The direct destruction of cells infected with intracellular bacteria, by cytotoxic T lymphocytes and natural killer cells.

Question 9

What are the 10 major mechanisms of immune defense against extracellular bacteria

Answer 9

Polysaccharides on the bacteria can act as Ti antigens and activate B cells that produce the IgM antibodies

Other bacterial components can act as Td antigens and activate B cells that produce the IgM and IgG antibodies

Neutralizing antibodies recognize bacterial pili (similar to flagella but shorter) and block access of these bacteria to host cell glycoproteins, thus preventing adhesion

Neutralizing antibodies bound to bacterial surface antigens act as opsonin and promote phagocytosis and destruction of the bacteria by macrophages and neutrophils. They also produce pro-inflammatory cytokines

B cell recognizing a bacterial toxin produces neutralizing anti-toxin antibodies that prevent the toxin molecules from damaging the cell surfaces

Bacteria that have been bound by antibody, along with C1, C3b, or mannose binding lectin (MBL), activate complement via all three pathways

Mast cells activated by an encounter with a FimH-expressing bacterium, release histamine and pro-inflammatory cytokines that lead to the recruitment of neutrophils

Bacterial components captured by dendrite cells (DCs) are processed and presented to CD4+ Th2 cells, which supports antibody production.

Evidences have shown that antibodies not only mark bacteria for destruction, but they can also be directly bacteriostatic (e.g. anti-E.coli Abs interfere with the secretion of iron chelator) or bactericidal (produce oxidants)

An anti- heat shock protein (HSPs) response against bacterial HSPs by some γ/δ T cells