Tetranectin in cerebrospinal fluid: biochemical characterisation and evidence of intrathecal synthesis or selective uptake into CSF.
BACKGROUND
Tetranectin (TN) is a 67 kDa glycoprotein thought to play a prominent role in the regulation of proteolytic processes via its binding to plasminogen and indirect activation of plasminogen. The TN concentration in serum is approximately 10 mg/l and is reduced in patients with several cancers. The TN concentration in the normal CSF has not been examined.


METHODS
The TN concentration in the serum and CSF of 47 normal subjects without neurological disorders was established using a polyclonal sandwich ELISA.


RESULTS
The median TN concentration (quartile range) was 10.8 mg/l (9.0-12.1) in serum and 0.43 mg/l (0.3-0.53) in CSF. The TN index median (quartile range), defined as (TN CSF concentration/TN serum concentration)/(Albumin CSF concentration/Albumin serum concentration), was found to be 5.5 (4.7-7.6), suggesting intrathecal synthesis or selective uptake of TN in CNS. Immunohistochemistry showed TN immunoreactivity in neurons and dendrites, but no staining in glial cells in the cerebrum and cerebellum. In plexus choroideus, the ependymal cells exhibited strong immunoreactivity. TN in serum and CSF were immunochemically identical and of similar size.


CONCLUSIONS
TN is present in normal brain and CSF, and the TN index is very high, but further studies are necessary to decide whether TN is synthesised in the CNS or selectively transported over the blood-brain barrier.
Stoevring
Birgitte
B
Department of Clinical Biochemistry, Statens Serum Institut, 5 Artillerivej, Copenhagen DK 2300 S, Denmark.
Jaliashvili
Irakli
I
Thougaard
Annemette V
AV
Ensinger
Christian
C
Høgdall
Claus K
CK
Rasmussen
Lars S
LS
Sellebjerg
Finn
F
Christiansen
Michael
M
D002555:Cerebrospinal Fluid; D002850:Chromatography, Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D037181:Lectins, C-Type / Q000032:analysis* / Q000096:biosynthesis
D037181:Lectins, C-Type; C048648:tetranectin