O. Jimenez1,2, M. H. Barros3, M. Cohen1,2, E. De Matteo1,2, M. Garcia Lombardi4, M. V. Preciado1,2, G. Niedobitek3, P. Chabay1,2
1 Molecular Biology Laboratory, Pathology Division, Ricardo Gutiérrez Children's Hospital, Buenos Aires, Argentina, 2 Multidisciplinary Institute for Investigation in Pediatric Pathologies (IMIPP), CONICET-GCBA, Buenos Aires, Argentina, 3 Institute for Pathology, Unfallkrankenhaus Berlin, Berlin, Germany, 4 Oncology Division, Ricardo Gutiérrez Children's Hospital, Buenos Aires, Argentina
The microenvironment in cHL is formed by different cell types, which -enable cancer pathogenesis and progression. Only a few studies were -performed in pediatric cHL, in which age and EBV infection may have a key role. In addition, EBV association with cHL in Argentina is significant in patients under 10 years old. Therefore, our aim was to characterize microenviroment composition in a pediatric cHL series. Formalin-fixed paraffin-embedded (FFPE) biopsy samples from 46 patients were collected from the archives at Pathology Division, Ricardo Gutierrez Children's Htal in Buenos Aires, Argentina and Tissue Microarray blocks were constructed. Tumor microenvironment immunophenotyping was performed with antibodies: CD4, CD8, Foxp3 (Treg), granzyme B (GrB). Macrophage polarization was assessed by double staining with pSTAT1 or CMAF followed by CD68 or CD163. Coexpression ofpSTAT1 with CD68 or CD163 identified M1-polarized macrophages, while CMAF with CD68 or CD163, identified M2-polarized macrophages. By means of CD68, 81% of cases displayed M1 polarization (CD68+pSTAT1+ / CD68+CMaf+ >1.5), 13% exhibited M2 pattern (CD163+pSTAT1+ / CD163+CMaf+ < 0.75) and 7% showed comparable numbers of M1 and M2. CD163 was used, 60% of cases demonstrated to be M1 polarization (CD163+pSTAT1+/CD163+CMaf+ >1.5), 37% proved to be M2 polarized (CD163+pSTAT1+ /CD163+CMAF+ <0.75), in spite of EBV presence and subtype distribution. In patients older than 10 years old, an immunoregulatory-rich environment characterized by higher Foxp3 expression was demonstrated (p = 0.0140). M1 polarization prevailed in patients younger than 10 years old, whereas M2 polarized cells were mostly observed in older patients, by both CD68 and CD163 double staining (p-0.004 and p = 0.0085, respectively, FE, test). Using CD68 as marker, CD4, CD8 and Foxp3 cell counts were similar in both M1 and M2 polarized microenvironments (p > 0.05, MW, test), whereas GrB+ cell numbers were significantly higher under M1 polarization (p = 0.0178, MW, test). Survival was influenced neither by macrophage presence nor by cytotoxic or immunoregulatory-rich status.This study reveals that age has an impact on microenviroment composition, given the fact that M2 polarized status previously described in adult may not be prevalent in children younger than 10 years.Cytotoxic and antitumor M1 environment in young pediatric patient might be ineffective to control lymphomagenesis process.