The fact that b cells and t cells are both clonally selected means that each b cell or t cell produces only one kind of antibody. there are five different types of immunoglobulin. each individual can form many different antibodies, but only one type of t cell receptor. specific t cells and b cells increase in number on recognition of an epitope. b cell lymphocytes change their antibody specificity to match a newly discovered antigen, then undergo mitosis to form a clone of plasma cells.