IMMUNOLOGY

Detailed explanation-1: -Helper T cells assist B cells to produce antibodies and assist killer T cells in their attack on foreign substances. The killer T cell must migrate to the site of infection and directly bind to its target to ensure its destruction.

Detailed explanation-2: -If an antigen enters the body and B-cells recognize it (either from having had the disease before or from being vaccinated against it), B-cells will produce antibodies. When antibodies attach to an antigen (think a lock–key configuration), it signals other parts of the immune system to attack and destroy the invaders.

Detailed explanation-3: -Adaptive immune responses are carried out by white blood cells called lymphocytes. There are two broad classes of such responses-antibody responses and cell-mediated immune responses, and they are carried out by different classes of lymphocytes, called B cells and T cells, respectively.

Detailed explanation-4: -Some of the cytokines produced by activated macrophages are chemoattractants (known as chemokines). Some of these attract neutrophils, which are the first cells recruited in large numbers to the site of the new infection.

Detailed explanation-5: -A major role of the T cell arm of the immune response is to identify and destroy infected cells. T cells can also recognize peptide fragments of antigens that have been taken up by APC through the process of phagocytosis or pinocytosis.

Detailed explanation-6: -T cells are a key component in the cell-mediated response-the specific immune response that utilizes T cells to neutralize cells that have been infected with viruses and certain bacteria. There are three types of T cells: cytotoxic, helper, and suppressor T cells.

Detailed explanation-7: -T cells can wipe out infected or cancerous cells. They also direct the immune response by helping B lymphocytes to eliminate invading pathogens. B cells create antibodies. B lymphocytes, also called B cells, create a type of protein called an antibody.