Lymphocytes, computer artwork. T- and B-lymphocytes are part of the immune system. B cells mature in bone marrow and are responsible for humoral immunity; they operate by recognising a specific site (antigen) on the surface of a pathogen or foreign object, which they bind to before producing antibodies to destroy that antigen. T cells mature in the thymus and are involved in cell-mediated immunity, which does not rely on antibodies to fight antigens, but rather the activation of other immune cells. Interaction between B and T cells can increase B cell antibody production.