Intramuscular injection of hrRANTES causes mast cell recruitment and increased transcription of histidine decarboxylase in mice: lack of effects in genetically mast cell-deficient W/WV mice.
RANTES (regulated upon activation, normal T cell expressed and presumably secreted) and other chemoattractant proteins are members of the intercrine or chemokine family of proinflammatory basic polypeptides. RANTES is a prototype of the C-C chemokine subfamily that acts as a selective chemoattractant for human monocytes and CD4-positive lymphocytes and increases the adherence of monocytes to endothelial cells. However, the role of RANTES in white cells is still unclear. We report here that hrRANTES at 20 ng/50 microl in mice causes mast cell recruitment 4 h after intramuscular injection, an effect inhibited by anti-RANTES, as evidenced by 0.1% Toluidine blue, a specific dye for coloring mast cells. Injections of PBS (50 microl) vehicle (negative control) did not produce any appreciable inflammatory response, whereas injection of lipopolysaccharide 20 ng/50 microl (positive control) generated a marked inflammatory state. When RANTES was injected intramuscularly in genetically mast cell-deficient W/Wv mice, the inflammatory effect was not present. The RANTES injection sites were then excised and studied under an optical and electron microscope. A Northern blot analysis was performed using a probe that was prepared to detect mRNA encoding the histidine decarboxylase (HDC) gene on excised muscle tissue. We found that hrRANTES provoked generation of HDC mRNA from muscle tissue after 4 h. These effects were inhibited by an anti-RANTES antibody and were absent in genetically mast cell-deficient mice. The increasing number of mast cells in the RANTES injection sites led to an augmentation of histamine content compared to controls (PBS). The injection of hrRANTES 20 ng/20 microl into the sole of a rat paw confirmed the inflammatory and the mast cell recruitment potential of this chemokine. In these studies, hrRANTES injections in muscle tissue provided direct in vivo evidence that RANTES has a significant effect on mast cell recruitment and HDC mRNA generation.
Conti
P
P
Immunology Division, University of Chieti School of Medicine, Chieti, Italy. pconti@unich.it
Reale
M
M
Barbacane
R C
RC
Letourneau
R
R
Theoharides
T C
TC
D000818:Animals; D018946:Chemokine CCL5 / Q000494:pharmacology*; D005121:Extremities; D006632:Histamine / Q000032:analysis; D006640:Histidine Decarboxylase / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D007273:Injections, Intramuscular; D007279:Injections, Subcutaneous; D008407:Mast Cells / Q000187:drug effects* / Q000648:ultrastructure; D051379:Mice; D008817:Mice, Mutant Strains; D018482:Muscle, Skeletal / Q000276:immunology / Q000648:ultrastructure; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D013194:Staining and Labeling; D014048:Tolonium Chloride
D018946:Chemokine CCL5; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014048:Tolonium Chloride; D006632:Histamine; D006640:Histidine Decarboxylase