Final answer:
B cells can recognize antigens in their natural form because their receptors bind to intact antigens. T cells require antigens to be processed and presented by MHC molecules on APCs before recognition. B cells are vital in producing antibodies for the humoral immune response.
Step-by-step explanation:
B cells are unique among lymphocytes because they can recognize antigens as they exist in nature without the need for these antigens to first be processed by antigen presenting cells (APCs). This capability is due to the presence of antigen receptors on the surface of B cells that can bind directly to intact antigens, such as bacterial carbohydrate and lipid molecules. Unlike B cells, T cells only recognize antigens that have been digested and presented on the surface of other cells within the binding groove of major histocompatibility complex (MHC) molecules.
Once B cells bind to an antigen, they can function as APCs themselves and can also differentiate into plasma cells that secrete antibodies. These antibodies then play a crucial role in the humoral immune response by recognizing and binding to pathogens directly. Therefore, B cells are critical for directly fighting off infections without the antigens first being processed by other cells.