Question

This year’s flu, which is dominated by H3N2 (an influenza A strain), has caused severe morbidity and mortality. The virus is usually spread through contact with aerosols and droplets, and introduced into epithelial cells of the respiratory tract. Both you and your wife caught flu two-three week ago, and had miserable time with similar symptoms although you got sick first and then she came down 1 week later. In addition to experiencing local symptoms, like sore throat and nasal congestion, you two also had systemic symptoms, such as fever and muscle pain. Many of these symptoms likely reflect ongoing immune reactions. Ten days later, you recovered completely. With the knowledge just learned in the past three lectures, please describe how your immune system worked to fight off the infection.

To determine if you developed virus-specific T cell immunity, you collected CD8+ T cells from your own blood (not your wife’s) and expanded some epithelial cells isolated either from your own nasal swap or nasal isolate of your wife (assuming you could collect these cells). These epithelial cells were infected in a test tube to serve as targets (i.e., target/H3N2) for analyzing activity of your CD8 cells. Specifically, you mixed your CD8+ cells with either your own epithelial cells (target-A) or epithelial cells derived from your wife (target-B), illustrated as below, would these target cells be killed by your CD8 cells and why?

1.CD8+ cells + Target-A/H3N2

2.CD8+ cells + Target-B/H3N2

Answer 1

1) The blood of the target A (male ) is taken and the CD8 + T-cells are isolated in a test tube. This blood is already infected with the influenza virus strain (H3N2). The body develops an immune response and starts producing antibodies against the foreign antigens. The T-cells secrete interferons chemical signals after reacting with the foreign antigen particles in the body. The nasal swab of this patient is isolated containing infected epithelial cells and grown along with the CD8 + T-cells in the test tube. The infected epithelial T-cells will react with the CD 8+ Tcells leading to the death by apoptosis due to the secretion of interferons and cytokines.

2) The CD8 + T cells from the male patient blood are isolated and mixed with the isolated nasal swab infected epithelial cells from the nasal swab of the patient B (wife). In this situation, the reaction and production of antiboides will not take place as it is an invitro experiment in the test tube and the strain of influenze virus(H3N2) infecting the patient B(wife) is different from the strain of the patient A (husband). The strains of the influenza virus are different in the two patients thus the reaction of the infected CD 8+ T cells with the infected epithelium cells of the nasal swab of the female patient wife.