IgG synthesis within the central nervous system. Comparison of three formulas
E. A. Schuller, S. Benabdallah, H. J. Sagar, J. A. Reboul and L. C. Tompe
IgG synthesis within the central nervous system is the expression of a
local pathologic immune reaction. Its detection is of great importance in a
large number of neurologic diseases, especially multiple sclerosis (MS).
The results obtained from the study of 115 neurologic patients (52 patients
with MS and 63 patients with other neurologic diseases) using three
different mathematic formulas (Tourtellotte's formula, the index of
Tibbling and coworkers, and Schuller and Sagar's formula) are presented and
statistically analyzed. Despite their obvious differences, the results from
these three formulas are in accordance in 76% of the patients observed. The
clinical correlations of these formulas are discussed; none of them allows
a specific diagnosis of MS. The formula of Schuller and Sagar seems the
most sensitive, detecting local central nervous system IgG synthesis in 79%
of patients with MS, compared with 54% of patients with MS utilizing the
index of Tibbling and coworkers and 50% of patients with MS utilizing
Tourtellotte's formula. No correlation was established between serum and
cerebrospinal fluid albumin concentrations, nor between serum albumin and
IgG levels in cerebrospinal fluid. Thus, no evidence exists to support the
inclusion of variations in serum albumin levels in the calculation of
intrathecal IgG synthesis. Furthermore, Schuller and Sagar's formula allows
classification of neuroimmunologic diseases and the evaluation of
antibody-specific activity (ASA) in locally produced IgG. The comparison of
intrathecal IgG ASA with serum IgG ASA, which reflects local and general
immunity, respectively, seems potentially important.
