Quantitative nephelometric microdetermination of alpha-globulins in serum and cerebrospinal fluid.

METHODS FOR THE QUANTITATIVE DETERMINATION of alpha-globulins in either blood or cerebrospinal fluid fall into three general categories: (a) alcohol or salt-fractionation technics, (b) electrophoretic analyses and (c) precipitation reactions with cationic detergents at controlled pH. Salt-fractionation procedures for a-globulins using sodium sulfate precipitation at a fixed concentration are those of Wolfson and Cohn (1) and of Kibrick and Blonstein (2). These clinical methods are suitable only for the high-protein concentrations found in serum, and both attempt to relate the chemical values to those obtained electrophoretically. While consistent checks between the two procedures can be obtained with normal sera, the careful experimental studies of Svensson (3) and Majoor (4) have shown that protein fractions precipitated at a single salt concentration do not correspond to those determined electrophoretically, especially for pathologic sera (5). The low temperaturelow ionic strength fractionation methods of Cohn, Edsall, and their associates (6) have been extended by Lever et al. (7) to the small-scale fractionation of 5-mi. plasma samples. While such procedures are not truly quantitative, in that only about 75 per cent of total plasma protein