A simple, rapid, and sensitive method of determining CSF IgG, using latex

A simple, rapid and sensitive method of determining cerebrospinal fluid IgG is presented. The procedure depends upon the fact that spinal fluid gamma globulin, and two of its components (IgG and IgM) will precipitate latex particles in proportion to their concentration, and that the optical density of the supernatant solution containing unprecipitated latex particles after centrifugation is inversely proportional to the concentration of these immunoglobulins. The method is sensitive to 50 nanograms, is inexpensive, requires 0.1 ml. or less of spinal fluid, and can be performed in minutes. Preliminary studies show that it compares favorably with results obtained by radial immunodiffusion.