Abstract
Much of our information about the structure, function, genetics and metabolism of immunoglobulins has come from studies of the homogeneous immunoglobulins associated with malignant diseases of the plasma cell or lymphocyte. Similarly, our understanding of cellular and other humoral factors involved in the immune response has been obtained from studies of patients with congenital or acquired immunodeficiency syndromes and from animals lacking essential cellular or organ components of the immune system — the so-called immunologic "experiments of nature." Over the past two decades we have witnessed a tremendous increase in our knowledge of the immune system with the identification of . . .