A practical immunological method for the assay of clinical biological solutions, such as allergen extracts, in agar gel plates is presented.
The method permits assay of individual antigens in antigenic mixtures.
Application of the method to the assay of three `unknown' dilutions of each of four grass pollen extracts gave results which were within –9 per cent and +6.7 per cent of the actual values.
It is postulated that an immunological assay, since it indicates the antigenic state of the solution, is a more valid index to the probable clinical potency of an allergen extract than the Noon, total nitrogen, or protein nitrogen units currently in use.
The quantitative gel plate assay method is quick and simple in application and suited to routine use.