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How do B cells produce antibodies after meeting an antigen?

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Immune stimulation by activated helper T cells — immune system Stimulation of immune response by activated helper T cells. Activated by complex interaction with molecules on the surface of a macrophage or some other antigen-presenting cell, a helper T cell proliferates into two general subtypes, T_H1 and T_H2. These in turn stimulate the complex pathways of the cell-mediated immune response and the humoral immune response, respectively.

When a B cell encounters a specific antigen, it undergoes activation and clonal expansion, a process that generates numerous cells with the same antigen specificity. This activation is often supported by helper T cells, which secrete cytokines that provide essential stimulation to the B cells.12

Following activation, some B cells differentiate into plasma cells. These specialized cells act as factories, secreting large quantities of antibodies that are closely modeled after the original receptors on the precursor B cell. Once released into the blood and lymph, these antibodies bind to the target antigen to initiate its neutralization or destruction.314

Other activated B cells differentiate into memory B cells, which remain in the body to provide long-lasting protection. If the same antigen is encountered again, these memory cells enable a faster and more robust immune response.1