Notice the dotted line for a CD4 count of 200. Why is that level important?   A This is the point at which ART should begin.   B CD4s of 200 represent the point at which HIV will begin to generate resistance mutations.   C When CD4s reach 200, a person is at great risk of disease from opportunistic infections, including ones that hardly ever cause disease in people with normal CD4s.

Notice the comment that after treatment your CD4 count should rise. Why does treatment allow CD4s to increase?   A Anti-retroviral therapy consists of transfusions of CD4 cells.   B Anti-retroviral therapy directly stimulates cell division of CD4 cells, so their numbers increase.   C Anti-retroviral therapy will prevent HIV from replicating and killing your CD4s. CD4s can grow back to some degree.

Wiskott–Aldrich syndrome is an immunodeficiency disease due to mutations in the gene encoding WASp. Individuals with this disease make poor antibody responses to protein antigens, due to impaired T cell help for B cells. WASp-deficient T cells are likely impaired in providing adequate help to B cells due to: A. Defects in up-regulating expression of genes encoding cytokines required by B cells B. Defects in up-regulating metabolic pathways for T cell macromolecular synthesis C. Defects in up-regulating expression of genes needed for T cell survival D. Defects in cytoskeletal reorganization needed for directed T cell cytokine secretion E. Defects in up-regulating T cell integrin adhesion for stable interactions with B cells

Identify the mismatched pair. a. MyD88: adaptor protein b. ICAM-1: LFA-1 c. chemokine receptor: G protein d. CD14: LPS e. NK cells: IFN-γ f. selectins: protein ligands.