Question

1. Which of the following mechanisms are the key effector mechanisms in controlling a viral infection such as COVID-19?

Select one:

1. Cytotoxic T cells and antibodies
2. T helper cells and cytotoxic T cells
3. Macrophages, NK cells and neutrophils
4. T helper cells and antibodies

2. Which of the following best describes the reason there is very little IgE present in the blood circulation?

Select one:

1. It is only produced in very small quantities in response to allergens
2. It is associated with mast cells
3. It is all adsorbed into the surrounding tissues
4. It is secreted across the gut wall

3. Upon engagement of a naïve CD4 T cell with its cognate (relevant) peptide being presented by a dendritic cell in the lymph node, the first step that the naïve CD4 T cell will take is:

Select one:

1. Migrate to the B cell zone to activate antigen specific B cells
2. Kill the dendritic cell to rid it of pathogen
3. Secrete IL-2
4. Proliferate to expand in number

Answer 1

Ans . (i) option (C) Macrophages, NK cells and neutrophils

The body responds to a viral infection immediately with a non-specific innate response in which macrophages, NK cells and neutrophils slow the progress of virus and may even prevent it from causing symptoms.

(ii) option (A) It is only produced in very small quantities in response to allergens

The circulating concentration of IgE is very low because B cells synthesize it at a very low rate and mast cells, basophils, and activated eosinophils bind up most of the circulating IgE.

(iii) option ( D) Proliferate to expand in number

The activation and clonal expansion of a naive T cell on initial encounter with antigen on the surface of an antigen-presenting cell is often called priming, to distinguish it from the responses of armed effector T cells to antigen on their target cells and the responses of primed memory T cells.