The present state and expected future development of methods for the determination of β-cell secretory products

Abstract

The insulin and C-peptide RIAs possess reproducibility and precision and are suitable for routine use, whereas the human proinsulin RIA remains more complicated. New antibodies with improved qualities continue to appear and the rabbit anti-C-peptide serum now introduced in a new kit from Novo is an example of a development where the main purpose was to secure long-term continuity in supply combined with high specificity and reproducibility of this widely used reagent. RIAs have maintained their position in most laboratories in spite of the promising ELISAs originally described about 10 years ago. Their detection limit was not up to that of RIA^3,74 and the benefit of avoiding ¹²⁵I is not without cost, as some of the ELISA reagents are not entirely harmless. On the other hand, the long shelf-life of the enzyme reagent, the speed and capacity are a great advantage, and a most promising ELISA for proinsulin was recently described²⁶, in which the ever-present non-specific serum interference seems to have been solved.