Quantitation of Immunoglobulins in Cerebrospinal Fluid

SEVERAL methods for quantitation of serum immunoglobulins (γG, γA, γM, and γD) have recently been developed,¹⁻³and they have aided in the diagnosis of various diseases. Since changes in the concentrations of proteins in cerebrospinal fluid (CSF) are known to occur in a variety of neurological diseases, similar absolute quantitation of the CSF immunoglobulins would be desirable. During the past few years CSF immunoglobulin evaluation has been primarily qualitative. Lattere et al⁴have shown that most of the immunoglobulins of CSF have the same antigenic determinants as do serum immunoglobulins. Stastny et al⁵has found that γG is the principal immunoglobulin of CSF. With these facts in mind, we have developed a relatively simple method for absolute quantitation of the immunoglobulins in small volumes of unconcentrated CSF. The method is a variation of the antibody-agar technique²,³commonly used for serum immunoglobulin quantitation. It involves the diffusion