Kj. Henderson et al., EXPRESSION OF CD44 IN NORMAL AND RHEUMATOID SYNOVIUM AND CULTURED SYNOVIAL FIBROBLASTS, Annals of the Rheumatic Diseases, 53(11), 1994, pp. 729-734
Objective-To determine if expression of CD44, the principal receptor f
or hyaluronan, was altered in rheumatoid (RA) synovium and cultured rh
eumatoid synovial fibroblasts. Methods-Synovium was obtained from norm
al adult human joints (n = 4) and from joints of patients with RA (n =
5). Specific monoclonal antibodies to CD44 were used in immunofluores
cence of whole synovium and cultured synovial fibroblasts and in quant
itative Western blotting and ELISA of CD44 in cultured synovial fibrob
lasts. Results-CD44 was restricted to the lining layer in normal synov
ium but present, in reduced concentrations, throughout rheumatoid syno
vium. Cultured rheumatoid cells were 19% larger in area and showed far
fewer and less extensive CD44-positive cytoplasmic extensions, togeth
er with reduced staining intensity compared with normal. Quantitative
Western blotting normalised for cell protein showed a 75% reduction (n
ormal = 1754 (835), rheumatoid = 409 (84) mean (SD) arbitrary units) i
n the amount of CD44 in rheumatoid cells compared with normal, and enz
yme Linked immunosorbent assay (ELISA) of cultured cell monolayers nor
malised for cell number indicated a 29% reduction (normal = 0.707 (0.1
10), rheumatoid = 0.504 (0.103), mean (SD) optical density at 405 nm).
Conclusions-Rheumatoid synovial cells showed altered morphology and r
educed CD44 expression compared with normal cells. CD44, by means of m
odulated associations with the cytoskeleton, may be involved in cell s
hape change.