Principles of albumin and IgG analyses in neurological disorders. III. Evaluation of IgG synthesis within the central nervous system in multiple sclerosis

Abstract

Fifty-nine multiple sclerosis patients were investigated with regard to blood-brain barrier function by determining the CSF-protein and the CSF/S albumin ratio. Abnormal values were found in 19% and 32% respectively. The occurrence of CSF-IgG elevation due to synthesis within the CNS was analysed by determining the CSF IgG/protein and CSF IgG/albumin ratios and the IgG-index = (CSF/S IgG ratio)/(CSF/S albumin ratio). Increased values were found in 75%, 80% and 86%, respectively. Oligoclonal IgG was found in CSF by agarose gel electrophoresis in 88% of the patients. The IgG-index is the parameter recommended for the demonstration of an IgG elevation in CSF due to synthesis within the CNS.

Type 1 Diabetes Mellitus and Drug-resistant Epilepsy: Presence of High Titer of Anti-Glutamic Acid Decarboxylase Autoantibodies in Serum and Cerebrospinal Fluid

“…Since anti-GAD antibodies are unable to cross the blood-brain barrier (18), the intrathecal-produced anti-GAD antibodies not from systemic circulation, are essential for the impairment of CNS. In the present case, anti-GAD-specific IgG index (1.62), an assessment index for intrathecal production of anti-GAD antibody (8), was greater than 1.0, thus lending a strong support for its intrathecal production (8,19). In addition, it has been shown that the characteristics of anti-GAD antibodies are different between type 1 diabetes and SPS: anti-GAD65 antibodies in type 1 diabetes may recognize conformational epitopes in the middle and C-terminus of the protein, whereas in SPS they recognize both the linear and conformational epitopes at Nterminus and C-terminus of GAD65 molecules (9,18,20, and 21).…”

Elevated LGI1‐IgG CSF index predicts worse neurological outcome

“…CSF index for LGI1‐IgG and subclasses as compared to serum was calculated according to the Link formula,12 modified for specific antibodies13, 14:$\frac{\text{LGI1 IgG titer in CSF/ LGI1 lgG titer in serum}}{\text{CSF Albumin (ng/mL)/ serum Albumin (ng/mL)}}$ …”

IgG intrathecal synthesis and specific antibody index in patients with neurocysticercosis

“…To characterize local immunoproduction we used Link & Tibbling IgG indices 21 , Tourtellote's daily IgG synthesis 22 , Thompson's nomogram (IgG quotient versus albumin quocient) 23,24 and protein isoelectrofocusing 26 . Anti-Taenia specific antibody indices were calculated by the method established by Reiber and Felgenhauer 7 , using an ELISA assay.…”