The second international reference preparation for human serum immunoglobulin E and the first British standard for human serum immunoglobulin E.

The IgE activity of a preparation of freeze-dried human serum, coded 75/502, was studied by eight laboratories in an international collaborative study, which also included the Medical Research Council Research Standard A coded 68/341. The preparation 75/502 had been dispensed into ampoules and divided into two batches. In 1977 one batch was established as the First British Standard for Human Serum Immunoglobulin E. The second batch was donated to the World Health Organization (W.H.O.). In 1980 the W.H.O. Expert Committee on Biological Standardization established the preparation as the second International Reference Preparation of Human Serum Immunoglobulin E with a potency of 5000 i.u. per ampoule.