|Helper T-Cells (CD4)
||A type of immune cell that stimulates killer T-cells, macrophages, and B-cells to make immune responses. A helper T-cell is a type of white blood cell and a type of lymphocyte. Also called CD4positive T-lymphocyte.
|Human Leukocyte Antigen (HLA)
||A type of molecule found on the surface of most cells in the body. HLAs play an important part in the body’s immune response to foreign substances. They make up a person’s tissue type, which varies from person to person. HLA tests are done before a donor stem cell or organ transplant to find out if tissues match between the donor and the person receiving the transplant. Also called human lymphocyte antigen.
||A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue. The two main types of lymphocytes are B-lymphocytes and T-lymphocytes. B-lymphocytes make antibodies, and T-lymphocytes help kill tumor cells and help control immune responses. A lymphocyte is a type of white blood cell.
|Major Histocompatibility Complex (MHC)
||A series of genes that code for cell surface proteins that control the adaptive immune response. The system is called H2 in mice and HLA (human lymphocyte antigen) in humans. Class I MHC contains three genes called HLA-A, B, and C; proteins from these genes are expressed on nearly all cells. Class II MHC genes are called HLA-DR, DQ, and DP; their proteins are expressed on antigen-presenting macrophages, dendritic cells, and B-cells.
||A protein found on T-cells (a type of immune cell) that helps keep the body’s immune responses in check. When PD-1 is bound to another protein called PD-L1, it helps keep T-cells from killing other cells, including cancer cells. Some anticancer drugs, called immune checkpoint inhibitors, are used to block PD-1. When this protein is blocked, the “brakes” on the immune system are released and the ability of T-cells to kill cancer cells is increased.
|Ras Gene Family
||A family of genes that may cause cancer when they are mutated (changed). They make proteins that are involved in cell signaling pathways, cell growth, and apoptosis (programmed cell death). Agents that block the actions of a mutated ras gene or its protein may stop the growth of cancer. Members of the ras gene family include KRAS, HRAS, and NRAS.
SOURCES: Adapted from http://www.cancer.gov/publications/dictionaries/cancer-terms (accessed May 18, 2016) and http://www.biology.arizona.edu/immunology/tutorials/immunology/10t.html (accessed May 18, 2016).