Question

Immunology (elaborate explanations are not necessary 3-4 sentences are suffice)

State timing, steps and cells involved in the innate immune response to bacterial antigens and contrast this with adaptive immune responses to the same antigen.

Explain how macrophages recognize bacteria and the host mechanisms that lead to recruitment of cells to sites of infection.

Explain how inflammation is triggered, the changes in cells at sites of infection that occur and how this relates targeting of both phagocytes and adaptive immune cells to the site of infection.

Explain the clonal selection theory.

Describe the timing and relate what is occurring at the cellular level at each stage of the primary and secondary immune response

Describe the complement cascade and it’s role in the immune response Describe three functions of antibodies in the immune response.

Answer 1

A.

• Bacterial infections can be both extracellular or intracellular.
• The innate immune response starts expressing within 4 hrs. of the infection and involve many cell types such as mast cells, phagocytes, macrophages, natural killer cells, neutrophils and dendritic cells.
• The innate immunity can be divided into 2 separate step - tissue recognition and effector mechanism.
• The Adaptive Immune Response refers to the aspects of the host immune response which depend on the generation of proteins which are highly specific to particular microbial antigenic moieties.

B.

• The molecular basis for the capacity of innate immune cells to recognize general molecular patterns has become clear.
• Innate immune cells possess various classes of membrane receptors, called as "Pattern Recognition Receptors", which bind to molecules such as LPS, dsRNA, or other generic molecules produced only by microbes.
• Several families of Pattern Recognition Receptors proteins exist but the prototypical family is known as the "Toll-like Receptor" family which not only allow innate immune cells to recognize that a microbial infection is present, but depending on which receptors are activated allow innate immune cells to roughly determine what type of infection is occurring (i.e. bacterial, viral, fungal, etc.).

C.

• Inflammation can be described as either acute or chronic.
• Acute inflammation is the initial response of the body to harmful stimuli and is caused by the increased movement of plasma and leukocytes (especially granulocytes) from the blood into the injured tissues. A series of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells within the injured tissue.
• Prolonged inflammation, known as chronic inflammation, leads to a progressive shift in the type of cells present at the site of inflammation, such as mononuclear cells, and is characterized by simultaneous destruction and healing of the tissue from the inflammatory process.

D.

• Clonal selection theory of antibody formation describes body's ability to recognize and respond to unlimited number of foreign antigens.
• The theory states that an antigen entering the body does not induce the formation of an antibody specific to itself—as some immunologists believed—but instead it binds to one unique antibody selected from a vast repertoire of antibodies produced early in the organism’s life.
• Although controversial at first, this theory became the foundation of modern immunology.