Cerebrospinal fluid (CSF) is a clear, colourless fluid located between the meninges, the protective membranes surrounding the brain and spinal cord. Its main function is to protect the brain and spinal cord from trauma, as well as supplying nutrients and removing waste products to support cerebral metabolism.
Local (intrathecal) synthesis of immunoglobulins within the CSF, occurs in a wide variety of central nervous system (CNS) disorders but is most commonly associated with CNS infection (e.g. viral encephalitis, cerebral malaria) or autoimmune disorders such as multiple sclerosis (MS).1
Quantitative IgG or free light chain (FLC) analysis may be used as a measure of intrathecal immunoglobulin synthesis. To ensure that these measurements represent intrathecal synthesis rather than proteins that have diffused from the blood, an index calculation (add link) based on immunoglobulin / FLC and albumin measurements from paired CSF and serum patient samples is used. Albumin measurements serve as a marker of the integrity of the blood-CSF barrier since it is never synthesised within the CNS.
