title: Tumour-infiltrating CD11b+ myelomonocytes and response to fractionated irradiation of human squamous cell carcinoma (hSCC) xenografts.
abstract: OBJECTIVE
  Bone marrow derived CD11b+ myelomonocytes have been shown to be recruited by the tumour and to promote tumour regrowth after irradiation. Here we investigated in a panel of well characterised hSCC tumour models the number of tumour-infiltrating CD11b+ cells and the association with response to clinically relevant fractionated irradiation.
  
  
  METHODS
  Six hSCC tumour models (UT-SCC-5, -14, -15, XF354, FaDu, SAS) xenografted in nude mice were excised after injection of pimonidazole hypoxia marker before irradiation and after 5 and 10 fractions. In parallel, TCD(50) (dose to cure 50% of the tumours) assays were performed to determine the response to 30 fractions within 6 weeks. The TCD(50) values have been previously published [1]. Double staining of CD11b and pimonidazole was performed using immunofluorescence. CD11b+ cells were counted in viable pimonidazole-negative areas (non-hypoxic) and pimonidazole-positive areas (hypoxic) of whole tumour cross-sections.
  
  
  RESULTS
  The median number of tumour-infiltrating CD11b+ cells either decreased or remained unchanged after 5 and 10 fractions in most of the tumour models. The density of CD11b+ cells in hypoxic areas was similar or lower than in non-hypoxic regions independently on treatment in majority of the tumour models. After 10 fractions the median CD11b+ cell density was significantly associated with the TCD(50) values after 30 fractions.
  
  
  CONCLUSIONS
  The data from our exploratory study suggest that tumour-infiltrating CD11b+ cells may contribute to local tumour control after fractionated irradiation, which supports to further study their prognostic value and to evaluate specific myelomonocyte targeting strategies to overcome radiation resistance.
authors: Experimental Radiotherapy, Technische Universität Dresden, Germany.
authors: Karolina
authors: K
authors: Zaleska
authors: Kerstin
authors: K
authors: Bruechner
authors: Michael
authors: M
authors: Baumann
authors: Daniel
authors: D
authors: Zips
authors: Ala
authors: A
authors: Yaromina
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000276:immunology*; D039481:CD11b Antigen / Q000528:radiation effects*; D002294:Carcinoma, Squamous Cell / Q000276:immunology* / Q000473:pathology / Q000532:radiotherapy*; D004195:Disease Models, Animal; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005455:Fluorescent Antibody Technique; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000528:radiation effects*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000276:immunology; D011897:Random Allocation; D014183:Transplantation, Heterologous
chemical_list: D014408:Biomarkers, Tumor; D039481:CD11b Antigen; D039841:Leukocyte L1 Antigen Complex