Plasma Total Immunoglobulin Assay
This assay was similar to the previous one. 50 μl plasma and 50 μl polyethylene glycol (PEG) was added to each well of a 96-well microtiter plate. After 2 h of incubation at room temperature, plates were centrifuged at 1000 G for 15 min. The protein content of the supernatant was determined by the assay described above. This value was subtracted from the total protein level, and the result was equal to the total immunoglobulin concentration of the plasma.