Aquaporin-4 antibodies are not related to HTLV-1 associated myelopathy.
BACKGROUND
The seroprevalence of human T-cell leukemia virus type 1 (HTLV-1) is very high among Brazilians (1:200). HTLV-1 associated myelopathy or tropical spastic paraparesis (HAM/TSP) is the most common neurological complication of HTLV-1 infection. HAM/TSP can present with an acute/subacute form of longitudinally extensive myelitis, which can be confused with lesions seen in aquaporin-4 antibody (AQP4-Ab) positive neuromyelitis optica spectrum disorders (NMOSD) on MRI. Moreover, clinical attacks in patients with NMOSD have been shown to be preceded by viral infections in around 30% of cases.


OBJECTIVE
To evaluate the frequency of AQP4-Ab in patients with HAM/TSP. To evaluate the frequency of HTLV-1 infection in patients with NMOSD.


METHODS
23 Brazilian patients with HAM/TSP, 20 asymptomatic HTLV-1+ serostatus patients, and 34 with NMOSD were tested for AQP4-Ab using a standardized recombinant cell based assay. In addition, all patients were tested for HTLV-1 by ELISA and Western blotting.


RESULTS
20/34 NMOSD patients were positive for AQP4-Ab but none of the HAM/TSP patients and none of the asymptomatic HTLV-1 infected individuals. Conversely, all AQP4-Ab-positive NMOSD patients were negative for HTLV-1 antibodies. One patient with HAM/TSP developed optic neuritis in addition to subacute LETM; this patient was AQP4-Ab negative as well. Patients were found to be predominantly female and of African descent both in the NMOSD and in the HAM/TSP group; Osame scale and expanded disability status scale scores did not differ significantly between the two groups.


CONCLUSIONS
Our results argue both against a role of antibodies to AQP4 in the pathogenesis of HAM/TSP and against an association between HTLV-1 infection and the development of AQP4-Ab. Moreover, the absence of HTLV-1 in all patients with NMOSD suggests that HTLV-1 is not a common trigger of acute attacks in patients with AQP4-Ab positive NMOSD in populations with high HTLV-1 seroprevalence.
Neuroimmunology Unit, Department of Genetics, Evolution and Bioagents, University of Campinas, Campinas, Brazil. fglehn@terra.com.br
Felipe
F
von Glehn
Sven
S
Jarius
Augusto C
AC
Penalva de Oliveira
Carlos Otávio
CO
Brandão
Alessandro S
AS
Farias
Alfredo
A
Damasceno
Jorge
J
Casseb
Adriel S
AS
Moraes
Ana Leda F
AL
Longhini
Klaus-Peter
KP
Wandinger
Benito P
BP
Damasceno
Brigitte
B
Wildemann
Leonilda M B
LM
Santos
D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000368:Aged; D000369:Aged, 80 and over; D051401:Aquaporin 4 / Q000097:blood / Q000276:immunology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D015153:Blotting, Western; D001938:Brazil / Q000453:epidemiology; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009471:Neuromyelitis Optica / Q000097:blood* / Q000175:diagnosis / Q000208:ethnology / Q000276:immunology; D015493:Paraparesis, Tropical Spastic / Q000097:blood* / Q000175:diagnosis / Q000208:ethnology / Q000276:immunology; D012367:RNA, Viral / Q000097:blood*; D012737:Sex Factors; D055815:Young Adult
D051401:Aquaporin 4; D001323:Autoantibodies; D012367:RNA, Viral