Chronic & Granulomatous Inflammation

Question 1

Define the term “ Chronic Inflammation”.

Question 2

Which is the most dominant cell type in most chronic inflammatory reactions?

Answer 2

Macrophages

Question 3

State the role of macrophages in chronic inflammatory reactions.

Answer 3

• Secrete Cytokines and growth factors that act on various cells to destroy foreign invaders and tissues and activate other cells, notably T- T-lymphocytes

Question 4

Outline the role of macrophages in Chronic Inflammation.

Answer 4

• Ingest and eliminate microbes and dead tissues like other phagocytes.
• Initiate the process of tissue repair and are involved in scar formation and fibrosis.
• Secrete mediators of inflammation e.g Cytokines ( TNF, IL-1 & chemokines) and contribute to initiation and propagation of inflammatory reactions .
• Display antigens to T-lymphocytes thus setting up a feedback loop for defense against microbes by CMI responses.

Question 5

List 3 subsets of CD4+ T- cells involved in chronic inflammation .

Answer 5

• Th1 cells - produce IFN-Y which activates macrophages via the Classical pathway.
• Th2 cells - secrete IL-4, IL-5 and IL-13 , which recruit and activate Eosinophils and are responsible for the alternative pathway of macrophage activation.
• Th17 cells - secrete IL-17 and other Cytokines which induce the secretion of chemokines responsible for recruiting neutrophils & monocytes into the reaction.

Question 6

Reason why Eosinophils are beneficial in controlling helminth infections but also contribute to tissue damage in immune reactions like allergy?

Answer 6

Eosinophilic granules contain Major Basic Protein , a highly charged cationic protein which is toxic to helminths but results in injury to host epithelial cells.