How does the production of antibodies by lymphocytes contribute to specific immunity?

Sourav PanNovember 8, 2024

Answered

Role of Antibodies in Specific Immunity

The production of antibodies by lymphocytes, particularly B cells, is a critical component of the adaptive immune system, which provides specific immunity against pathogens. This process involves several key steps and mechanisms that ensure a tailored and effective immune response.

Lymphocyte Activation and Differentiation

1. Recognition of Antigens:
   • B cells express unique receptors (B cell receptors, or BCRs) on their surface that specifically bind to antigens, which are foreign molecules recognized by the immune system.
   • Upon encountering their specific antigen in secondary lymphoid organs (such as the spleen and lymph nodes), B cells become activated.
2. Clonal Selection:
   • The clonal selection theory posits that each B cell is pre-committed to respond to a specific antigen. When a B cell binds to its corresponding antigen, it undergoes proliferation and differentiation into effector cells.
   • This results in the formation of a clone of cells that produce antibodies specific to the encountered antigen.
3. Differentiation into Plasma Cells:
   • Activated B cells differentiate into plasma cells, which are specialized for antibody production. These plasma cells can secrete large quantities of antibodies into the bloodstream.
   • Additionally, some activated B cells become memory B cells, which persist long-term and enable a quicker response upon re-exposure to the same antigen.

Antibody Structure and Function

• Antibodies are Y-shaped proteins composed of four polypeptide chains. The tips of the Y contain variable regions that determine the specificity of the antibody for its antigen.
• Each antibody binds specifically to its corresponding antigen, enhancing the immune system’s ability to recognize and neutralize pathogens through various mechanisms:
  • Neutralization: Antibodies can block pathogen entry into host cells.
  • Opsonization: Antibodies mark pathogens for destruction by phagocytes.
  • Complement Activation: Antibodies can initiate the complement cascade, leading to pathogen lysis.

Immunological Memory

One of the hallmarks of specific immunity is the ability to remember past infections. Memory B cells formed during an initial immune response allow for a faster and more robust response upon subsequent exposures to the same pathogen. This immunological memory is crucial for long-term protection against diseases