Y. Hatano et al., Macrophage inflammatory protein 1 alpha expression by synovial fluid neutrophils in rheumatoid arthritis, ANN RHEUM D, 58(5), 1999, pp. 297-302
Objective-To determine the contribution made by synovial fluid (SF) neutrop
hils to the augmented expression of macrophage inflammatory protein 1 alpha
(MIP-1 alpha) in rheumatoid arthritis (RA).
Methods-Neutrophils were isolated from samples of SF from RA. patients and
peripheral blood (PB) samples from RA patients and healthy controls. Cell a
ssociated MIP-1 alpha was visualised immunohistochemically, and cell associ
ated MIP-1 alpha as well as MIP-1 alpha secreted into the SF was assayed by
ELISA. Steady state expression of MIP-1 alpha mRNA was assessed by reverse
transcription polymerase chain reaction (RT-PCR).
Results-Freshly isolated SF neutrophils contained significantly higher conc
entrations of both MIP-1 alpha protein and its transcript than PB neutrophi
ls from either RA patients or healthy controls; incubation in the absence o
r presence of tumour necrosis factor a for 24 hours resulted in a significa
nt increase in MIP-1 alpha secretion by RA SF neutrophils compared with neu
trophils obtained from either normal PB or RA PB; and expression of MIP-1 a
lpha by SF neutrophils was well correlated with both RA disease activity an
d SF mononuclear cell (MNC) counts.
Conclusion-Expression and secretion of MIP-1 alpha by SF neutrophils may be
indicative of local and systemic inflammation in RA. Moreover, this C-C ch
emokine may contribute to the recruitment of MNCs from the bloodstream into
synovial joints and tissues.