Application of serological methods as a means of solving problems in plant nematology developed more slowly than in some disciplines. The isolation of specific monoclonal antibodies has led to the creation of "plantibodies", Fv portions of mouse immunoglobulins expressed in planta, capable of interfering with the action of nematode saliva. Nematode antigens have been presented as whole nematodes, homogenates, or purified proteins in phosphate-buffered saline. The saliva of plant-parasitic nematodes certainly controls the development and maintenance of syncytia and giant cells. Intrasplenic immunization is the route of choice when only minute amounts of antigen are available. Different strains of mice also differ in their nonimmune response to nematode antigens. Prior to the purification of an antibody it is important to establish the isotype and class, since this will dictate which procedures are subsequently undertaken. Substantial losses of a mAb or its immunoreactivity may occur during purification.