Quantitative Nephelometric Microdetermination of Alpha-Globulins in Serum and Cerebrospinal Fluid

1. A micronephelometric method is presented for the quantitative determination of total α-globulins in both serum and cerebrospinal fluid. The method is based on the relatively specific interaction of this protein fraction with the cationic detergent, Octab, at pH 6.65 in collidine-NaCl (.08M) buffer. 2. The various Cohn's protein fractions (Method 6) (25) were investigated with the nephelometric procedure. In comparison with normal serum, Fractions IV-6, IV-1, and IV-4, respectively showed the greatest detergent reactivity per milligram of α-globulin. 3. The variations of such factors as the concentrations of reagents, protein/detergent ratio, and salt concentration were reinvestigated. 4. Analysis of 14 normal and 33 pathologic sera gave excellent checks with the total α-globulin values obtained with the Tiselius electrophoretic method. 5. Application of the procedure to the analysis of the α-globulin content of cerebrospinal fluid required the addition of standard serum to 0.5-ml. aliquots of spinal fluid for stoichiometric results.