Question

1a. I am culturing three breast cancer cell lines in the lab, made from cancer patients A, B, and C. All 3 patients are survivors. When I add white blood cells from the peripheral blood of the patients to the the cells lines, I find that A's blood cells kill A's tumor, but not B's or C's; B's blood cells kill B's tumor, but not A's or C's; and C's blood cells kills C's tumor, but not A's or B's. I conclude that the cell type doing the killing is:

Macrophages

Th1 cells

Activated B cells

NK cells

CTL cells

b. To infect a T cell, HIV must bind to:

A)

CD4 and CD8
B)

CD8 and gp120
C)

CD4 and CCR5
D)

CD4 and the T cell receptor
E)

CD8 and CCR5

Answer 1

The specific cell type that kills tumor cells in this scenario is the CTL (Cytotoxic T Lymphocyte) cell, which is responsible for the cell-mediated immune response. For HIV to infect a T cell, it must bind to CD4 and CCR5 on the T cell.

Step-by-step explanation:

When analyzing the interaction between breast cancer cell lines from patients A, B, and C with their respective white blood cells, we observe specificity in the ability to kill the cancer cells. Given this specificity and the nature of the interactions, the type of cell likely responsible for the killing of the tumor cells would be CTL (Cytotoxic T Lymphocytes).

CTL cells are a type of T cell that plays a crucial role in the cell-mediated immune response. Unlike other immune cells, such as macrophages or B cells, CTLs specialize in destroying cells that have been compromised, such as those infected with pathogens or cancerous cells. They identify their targets through the presentation of specific antigens by MHC class I molecules on the surface of these compromised cells. When a CTL recognizes a cell presenting its specific antigen, it will bind to that cell and induce its destruction.

Regarding HIV infection of T cells, for the virus to successfully bind and infect a T cell, HIV must bind to CD4 and CCR5. These are the receptor and co-receptor, respectively, often used by HIV to enter the host T cell. CD4 is a protein predominantly on the surface of helper T cells, while CCR5 is a chemokine receptor that acts as a coreceptor for HIV entry. HIV does not use CD8, which is found on cytotoxic T cells, the T cell receptor, which is involved in antigen recognition, or gp120, which is a glycoprotein on the HIV envelope that binds to CD4.