QS Study

Role of lymphocyte in defense of the body

Lymphocytes help in the defense of body by forming immunity. Lymphocytes are mainly involved in the body’s immune response system. This involves multifaceted phenomena which end in the expansion of humoral and cellular immunity.

Humoral immunity involves the construction of antibodies and is brought about by lymphocytes, which are called B-cells. Cellular immunity includes delayed hypersensitivity reactions, graft rejection, graft-versus-host reactions, defense against intracellular organisms, and probably a defense against neoplasms. There are three main types of lymphocytes: B cells, T cells, and natural killer cells.

  • T lymphocyte for cellular immunity – develop from liver or bone marrow stem cells that mature in the thymus.
  • B Lymphocyte for humoral immunity – develop from bone marrow stem cells in adults.

During fetal development, lymphocyte precursors come from the bone marrow. In the thymus, Precursors cells transformed into ‘T’ lymphocyte. In the liver and spleen precursor cells transformed into ‘B’ Lymphocyte. ‘T’ lymphocytes differentiate into 4 different varieties and B lymphocyte differentiates into plasma cells and memory ‘B’ cells. The Plasma cells secrete large quantities of antibody (immune-globulin) into general circulation. An antibody may coat bacteria and neutralizes bacterial toxins.

Lymphocytes flow in blood and lymph fluid and are found in body tissues including the spleen, thymus, bone marrow, lymph nodes, tonsils, and liver. Their various functions allocate them to appropriately react to foreign invaders in the body. Some lymphocytes work alone, while others are able to coordinate with other cells.