Release of soluble ICAM-5, a neuronal adhesion molecule, in acute encephalitis.
BACKGROUND
Intercellular adhesion molecule (ICAM)-5 (telencephalin) is an adhesion molecule in telencephalic neurons of the mammalian brain that binds to the leukocyte integrin CD11a/CD18. The authors observed that human cerebral neurons also expressed ICAM-5 and that ICAM-5--mediated neuron--leukocyte binding in cultured hippocampal neurons. This led the authors to examine ICAM-5 expression during clinical CNS inflammation.


METHODS
The authors found, by immunoblotting, a 115-kDa soluble form of ICAM-5 (sICAM-5) cleaved from the membrane-bound (130 kDa) ICAM-5, and established an ELISA assay to measure it. CSF samples of patients with acute encephalitis and MS were studied.


RESULTS
sICAM-5 was increased in encephalitis (320 plus minus 107 ng/mL; n = 25), as compared with patients with MS (128 plus minus 10 ng/mL; n = 16) and control subjects without CNS disease (137 plus minus 6 ng/mL; n = 42) (p < 0.001). The concentration of sICAM-5 correlated with the performance in the immediate recall task (p = 0.013) and with the leukocyte count in the CSF (p = 0.02), especially in cases caused by herpes simplex virus (HSV) (r = 0.94; p = 0.002).


CONCLUSIONS
sICAM-5 is cleaved from CNS into CSF during acute encephalitis, and it may mediate leukocyte--neuron interactions. sICAM-5 release from cerebral neurons may actively regulate immune responses and leukocyte adhesion during microbial neuroinvasion in humans during encephalitis.
Lindsberg
Perttu J
PJ
Department of Neurology, Helsinki University Central Hospital, FIN-00029 HUS, Helsinki, Finland. perttu.lindsberg@hus.fi
Launes
J
J
Tian
L
L
Välimaa
H
H
Subramanian
V
V
Sirén
J
J
Hokkanen
L
L
Hyypiä
T
T
Carpén
O
O
Gahmberg
C G
CG
D000208:Acute Disease; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001923:Brain Chemistry; D015815:Cell Adhesion Molecules; D004660:Encephalitis / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019169:Jurkat Cells; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis / Q000378:metabolism*; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012995:Solubility
D015815:Cell Adhesion Molecules; C086747:ICAM5 protein, human; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins