B lymphocyte is the only cell that is able to secrete antibody.
Specific B cells bind native antigen to the B cell antigen receptor on the cell surface and the bound antigen is subsequently internalized and delivered to an appropriate subcellular compartment for processing. Processing involves the conversion of protein antigens into peptides and the assembly of complexes of the antigenic peptide and Major Histocompatibility Complex class II molecules. The antigenic peptide-class II complexes are displayed on the surfaces of B cells for the recognition of helper T cells. The interaction between B cells and helper T cells activates the T cells to secrete growth and differentiation factors which activate B cell to become antibody-secreting cells. Therefore the ability of B cells to process and present antigen to helper T cells is critical to the activation of antigen specific B cells and T cells and T cell dependent antibody responses.