Progress in standardization: 4 immunological reagents.

The need for material standards in the field of clinical immunology, together with the mode of operation of the combined World Health Organization/International Union of Immunological Societies programme for the provision of such standards, are discussed. Attention is drawn to the importance of the use of International Units in reporting concentrations of complex constituents, e.g., immunoglobulins in body fluids, and to the availability of standard materials against which such components can be calibrated. The necessity for the standardization of nomenclature is also emphasized.