The humoral response
B lymphocytes, or B cells, take part in the specific immune response that produces antibodies against foreign antigens. This antibody-based defence is the humoral response.
A mature B lymphocyte has a surface antibody receptor with a particular antigen-binding shape. Other B lymphocytes carry receptors with different specificities.
An antigen can therefore bind only to B cells whose receptors have a complementary shape. This specificity determines which B lymphocyte is activated during the response.
Receptor specificity
The large range of B lymphocytes provides many different receptor shapes. When a particular antigen enters the body, only the B-cell receptor that fits that antigen can bind to it.
Recognition therefore depends on the complementary shapes of the antigen and the antigen-binding site of the surface antibody.
Helper T cells can stimulate B lymphocytes during the specific immune response, helping activated B cells progress towards antibody production.
Exam Tip: For B-cell specificity, link the surface antibody receptor to its complementary antigen. The antigen does not activate every B cell; it selects the B cell with the matching receptor.