B2 [ U ] a situation in which people are peaceful and agree with each other, or when things seem right or suitable together: racial harmony (= good feelings between different races) domestic harmony (= good feelings in the family or home) Imagine a society in which everyone lived together in (perfect) harmony. We must ensure that tourism develops in harmony with the environment.
Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells. The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells. The killer T cell has receptors that are used to search each cell that it meets.
T cells have a variety of roles and are classified by subsets. T cells are divided into two broad categories: CD8+ T cells or CD4+ T cells, based on which protein is present on the cell's surface. T cells carry out multiple functions, including killing infected cells and activating or recruiting other immune cells.heir coordinated movement and exchange of signals then instructs other innate immune cells called macrophages and monocytes (in green) to surround the neutrophil cluster and form a tight wound seal. This 24-second video represents a two-hour recording.