Myeloid related protein 8 and 14 secretion reflects phagocyte activation and correlates with disease activity in juvenile idiopathic arthritis treated with autologous stem cell transplantation.
OBJECTIVE
To determine whether myeloid related proteins (MRP8/MRP14), a complex of two S100 proteins related to neutrophil and monocyte activation, might be used as a marker for disease activity, and as an early indicator of relapse in juvenile idiopathic arthritis.


METHODS
A group of 12 patients who underwent an autologous haematopoietic stem cell transplantation (ASCT) for refractory juvenile idiopathic arthritis (JIA) were studied. MRP8/MRP14 serum concentrations were determined by a sandwich enzyme linked immunosorbent assay (ELISA) as described. Improvement from baseline was described by a definition of improvement employing a core set of criteria as detailed previously by Giannini.


RESULTS
After ASCT, MRP8/MRP14 serum concentrations in JIA showed a positive correlation with the Child Health Assessment Questionnaire (CHAQ; r=0.80) and erythrocyte sedimentation rate (r=0.45), but not with the total leucocyte count (r=0.26). Mean MRP8/MRP14 serum concentrations dropped markedly in the first three months after ASCT (p=0.0039) and clinical parameters of disease activity such as CHAQ markedly improved (p=0.0039). During a transient relapse there was an increase in MRP8/MRP14.


CONCLUSIONS
MRP8/MRP14 serum concentration can be used as a marker for disease activity in patients who receive an ASCT for refractory JIA. This indicates a role of macrophage activation in the pathogenesis of JIA. The occurrence of MAS in three patients in this study was not preceded by significant changes in MRP8/MRP14 concentration.
Wulffraat
N M
NM
Department of Paediatric Immunology, Wilhelmina Children's Hospital, University Medical Centre Utrecht, The Netherlands. N.Wulffraat@wkz.azu.nl
Haas
P J
PJ
Frosch
M
M
De Kleer
I M
IM
Vogl
T
T
Brinkman
D M C
DM
Quartier
P
P
Roth
J
J
Kuis
W
W
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D001327:Autoimmune Diseases / Q000097:blood; D001799:Blood Sedimentation; D040501:Calgranulin A / Q000097:blood*; D040502:Calgranulin B / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D010586:Phagocytes / Q000502:physiology*; D012008:Recurrence; D014182:Transplantation, Autologous
D040501:Calgranulin A; D040502:Calgranulin B