State the functions of: (a) lymphocytes – antibody production (b) phagocytes – engulfing pathogens by phagocytosis

Here are the functions of lymphocytes in antibody production and phagocytes in engulfing pathogens by phagocytosis:

(a) Lymphocytes – Antibody Production

• Function: Lymphocytes, specifically B cells, are crucial for the adaptive immune response. Their primary role is to produce antibodies that target specific antigens (foreign substances such as bacteria and viruses).
• Mechanism:
  • When a B cell encounters an antigen that matches its specific receptor, it binds to the antigen, which activates the B cell.
  • The activated B cell undergoes clonal expansion, multiplying into a large number of identical cells.
  • Some of these cells differentiate into plasma cells, which are specialized for producing large quantities of antibodies. These antibodies are released into the bloodstream and lymphatic system.
  • The antibodies bind to the specific antigens, marking them for destruction or neutralization by other immune cells. This process is essential for clearing infections and providing long-term immunity through memory B cells, which remain in the body to respond more rapidly if the same antigen is encountered again in the future.

(b) Phagocytes – Engulfing Pathogens by Phagocytosis

• Function: Phagocytes, including neutrophils and macrophages, are key players in the innate immune response. Their primary role is to identify, engulf, and destroy pathogens and debris through a process called phagocytosis.
• Mechanism:
  • When a phagocyte detects pathogens (often through pattern recognition receptors that bind to pathogen-associated molecular patterns), it initiates phagocytosis.
  • The phagocyte extends its plasma membrane around the pathogen, forming pseudopodia that surround and engulf the particle.
  • Once fully enclosed, the pathogen is trapped in a membrane-bound vesicle known as a phagosome.
  • The phagosome then fuses with lysosomes to form a phagolysosome, where digestive enzymes and reactive oxygen species break down and destroy the engulfed pathogen.
  • This process not only eliminates pathogens but also helps present antigens from the pathogens on the surface of phagocytes to activate other immune cells, thus linking innate and adaptive immunity