VMC 221: Veterinary Immunology and Serology (1+1)

Cellular components of the Adaptive immune system

CELLULAR COMPONENTS OF ADAPTIVE IMMUNE SYSTEM

• The principal cells of the immune systems are lymphocytes, antigen presenting cells (APCs) and effector cells. Lymphocytes specially recognize foreign antigen and respond in two different ways
  • Humoral immunity
  • Cell mediated immunity
• B lymphocytes when recognize antigens (extra cellular), they are differentiated in to antibody secreting cells and function as the mediators of humoral immunity.
• T- lymphocytes recognize, intracellular antigen and destroy the microbes or infected cells. They do not produce antibody. T lymphocytes do not respond to soluble antigens but they recognize peptide antigen attached to host proteins and produce different lymphokines to eliminate the antigen.
• The third class of lymphocytes, natural killer (NK) cell is also involved in innate immunity to remove intracellular organisms.
• For specific immune response, the antigen must be captured and presented to specific lymphocytes. The cells, which perform this function, are called antigen-presenting cells (APCs). They are mostly dendritic cells.

• Effector cells perform numerous functions to eliminate the antigen. Activated T lymphocytes, mononuclear phagocytes and other leukocytes function as effector cells in different immune responses.