PATHOLOGY

Detailed explanation-1: -White blood cells move through blood and tissue throughout your body, looking for foreign invaders (microbes) such as bacteria, viruses, parasites and fungi. When they find them, they launch an immune attack.

Detailed explanation-2: -T lymphocytes are cells that are programmed to recognize, respond to and remember antigens. T lymphocytes (or T cells) contribute to the immune defenses in two major ways.

Detailed explanation-3: -In cell-mediated immune responses, the second class of adaptive immune response, activated T cells react directly against a foreign antigen that is presented to them on the surface of a host cell.

Detailed explanation-4: -Immune responses are mediated by leukocytes, which derive from precursors in the bone marrow. A pluripotent hematopoietic stem cell gives rise to the lymphocytes responsible for adaptive immunity, and also to myeloid lineages that participate in both innate and adaptive immunity.