Chemotherapy Biotherapy Certification ONS Practice Test 2025 - Free Practice Questions and Study Guide

B cells, also known as B lymphocytes, are the specific type of lymphocytes responsible for the production and secretion of antibodies. They play a central role in the humoral immune response, which involves identifying pathogens like viruses and bacteria. Once B cells encounter an antigen that matches their specific receptor, they become activated, proliferate, and differentiate into plasma cells. These plasma cells are the ones that secrete large quantities of antibodies, which bind to the antigens and help neutralize or eliminate them from the body.

In terms of their prevalence, B cells make up about 20-30% of the total population of circulating lymphocytes. This is important because it highlights their contribution to the adaptive immune system and the body's ability to remember previous infections through the production of memory B cells after initial exposure to an antigen.

The other options—T cells, dendritic cells, and macrophages—have distinct roles within the immune system. T cells are primarily involved in cell-mediated immune responses, dendritic cells act as antigen-presenting cells that activate T cells, and macrophages function mainly in phagocytosis and help in cleaning up dead cells and pathogens. However, none of these cell types are responsible for the secretion of antibodies like B cells are.