S. Gautam et al., CHEMOKINE EXPRESSION IN TRINITROCHLORABENZENE-MEDIATED CONTACT HYPERSENSITIVITY, Journal of leukocyte biology, 55(4), 1994, pp. 452-460
The expression of the murine IP-10 and MCP-1 genes has been examined i
n the skin of mice during contact hypersensitivity reactions to the ha
pten trinitrochlorobenezene (TNCB). In both naive and passively sensit
ized animals, challenge with TNCB resulted in elevated expression of b
oth genes as early as 4 h as detected by Northern hybridization analys
is. Twenty-four hours after challenge, expression was markedly reduced
in naive animals but remained elevated in sensitized animals. This pr
olonged expression of chemokine gene products correlates with the tiss
ue swelling response generally used as a measure of delayed-type hyper
sensitivity (DTH) in this model and suggests that the continued expres
sion of these genes results from the stimulation of hapten-specific T
helper cells. Examination of cell type expression patterns by in situ
hybridization using H-3-radiolabeled riboprobes confirmed the results
of Northern hybridization experiments. Both genes were expressed predo
minantly in cells exhibiting the morphology of connective tissue fibro
blasts, although the distribution of cells positive for IP-10 mRNA exp
ression differed from that of cells expressing MCP-1 mRNA. IP-10 expre
ssion was localized almost exclusively to a population of connective t
issue cells surrounding the fur follicle. MCP-1 expression was rarely
found associated with fur follicles but instead was distributed throug
hout the dermis in cells embedded in the collagenous extracellular mat
rix. Surprisingly, neither endothelial cells lining the small vessels
located deep within the dermis nor epidermal keratinocytes were positi
ve under any of the conditions utilized in the present study. Expressi
on of both IP-10 and MCP-1 has been previously reported in a variety o
f distinct cell types in vitro. The present results indicate that only
a subset of the cell types with such potential are stimulated to expr
ess these chemokine genes in vivo during hapten-mediated DTH responses
, implying the presence of subtle cell type- and tissue-specific contr
ol mechanisms.