Question

Which of the following cell types are formed from a myloid precursor?

		mast cell
		B cell
		dendritic cell
		natural killer cell
		macrophage
		neutrophil
		plasma cell
		T cell

Which compliment pathway results in the production of MAC?

		Alternative Pathway
		Classic Pathway
		Manose-binding Lectin Pathway

Answer 1

• Which of the following cell types are formed from myeloid precursor?

Mast cells, dendritic cell, macrophage, neutrophil, dendritic cell

Explanation:

There are two types of stem cells: stem cell and lymphoid stem cell.

Myeloid stem cells:

Myeloid stem cells are pluripotent (trilineage) in nature giving rise to three types of different progenitor cells. These are erythroid progenitors that form the erythroid series, granulocyte progenitors that form the granulocytes (neutrophil, eosinophil, basophil), monocyte progenitors from monocytes, macrophage, dendritic cell s, and megakaryocytic progenitors forms the platelets.

Lymphoid stem cell:

They are unipotent stem cells that produce only cells of lymphocytes series (B cell, Tcell, NK cell).

• Which complement pathway results in the production of MAC?

Answer: classical pathway, alternative pathway, Mannose-binding lectin pathway

Explanation:

There are three pathway of complement activation:

Classical pathway: This is an antibody-dependent pathway. The pathway is triggered by the antigen-antibody complex.

Alternative pathway: This is an antibody independent pathway, triggered by the antigen directly.

Lectin pathway: It resembles classical the pathway, but it is antibody independent.

Stages of complement activation:

• Initiation of the pathway
• Formation of C3 convertase
• Formation of C5 convertase
• Formation of membrane attack complex

All three pathways differ from each other in relation to their formation of C3 convertase. Then, the remaining stages are identical in all pathways.

Formation of membrane attack complex:

It begins with the cleaving of C5 into C5a. Further, there is binding of C6 to C9 (There is formation of C5b6789). This is called membrane attack complex.

Each tubular channel behaves hydrophobic outside, but hydrophilic inside, thus allowing free passage of ions and water into the cell leading to cellular swelling and lysis. This process of cytolysis is referred to as complement-mediated cytotoxicity.