Even the simplest immunogens include several antigenic determinants and therefore stimulate many lymphocyte clones to proliferate. In general, foreign molecules must be larger than about 5 kd to be immunogenic . The clonal response has two consequences. A second consequence is immunologic memory . Some cells in the proliferating clone remain as undifferentiated responsive cells bearing the original specific receptor.
Immunologic memory is the basis for immunity to specific antigens and can last for many years.
Acquisition of tolerance involves killing of lymphocyte clones that respond to self antigens, at an early stage of development. The structure of antibody molecules Homogeneous antibodies for structure determination were first obtained from myeloma tumor cells. This extremely useful technique has found broad application in research, industry, medical diagnosis, and treatment. Antibodies are classed according to their heavy chains. Each class mediates a different set of effector functions for antigen elimination.