Quantitative comparison of cytokine mRNA and inflammatory responses in cutaneous late phase allergic reactions

The aim of this study was to quantitatively compare expression of mRNA for IL-5 and IFN-gamma with the frequency of mRNA-positive cells, total and act ivated eosinophils, neutrophils, lymphocytes, and vessels expressing adhesi on molecules. Replicate biopsies of skin LPR to pollen antigens (Ag) and co ntrol injection sites (B) at 6 and 24 h were assessed for: (1) mRNA for IL- 5 and IFN-gamma by quantitative RT-PCR (QC-RT/PCR); (2) frequency of cells expressing mRNA for IL-5 and IFN-gamma by in situ hybridization (ISH); (3) inflammatory cells and adhesion molecule expression. More mRNA for IL-5 was found in Ag- than in B-injected sites at 6 and 24 h by both QC-RT/PCR and ISH. Small amounts of mRNA for IFN-gamma were detected in Ag sites by QC-RT /PCR at 6 and 24 h, but mere not significantly different than at B sites. T he frequency of IFN-gamma mRNA(+) cells was higher in Ag than in B sites at 6h, There was no correlation between the amount if IL-5 detected by QC-RT/ PCR and frequency of IL-5 mRNA(+) cells by ISH, These findings also did not correlate with the degree of inflammatory responses. In conclusion: (1) gr eater IL-5 than IFN-gamma deposition in Ag sites suggests Th-2 predominance in LPR; (2) lack of correlation between QC-RT/PCR and ISH findings may ref lect varying mRNA content of inflammatory cells. (C) 2000 Academic Press.