Which one of the following statements about the immune system is false? A. A vir

Question

Which one of the following statements about the immune system is false?

A. A virus causes immune deficiency by infecting macrophages. Cytotoxic T-cells whose receptors recognize this virus should be able to kill virus-infected macrophages.

B. The clonal selection theory explains how antigens activate specific lymphocytes.

C. Each IgM molecule has ten sites with identical antigen binding specificity.

D. Dendritic cells express only MHC class II molecules on their surface, not MHC class I.

E. Agglutination of bacteria facilitates phagocytosis.

Explanation / Answer

Answer A) A virus causes immune deficiency by infecting macrophages. Cytotoxic T-cells whose receptors recognize this virus should be able to kill virus-infected macrophages.

Reason- Certain viruses such as Human Immunodeficiency Virus (HIV) can infect the Dendritic cells, Macrophages and the helper T cells (which are particularly CD4+ T cells). this lead to a decrease in the population of infected CD4+ cells. a decreased level below the critical value causes the Immune Deficiency.

therefore, virus infecting only the macrophages do not lead to immune deficiency.

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