Introduction: Human testicular germ cell tumours, i.e. seminoma, and pre-invasive germ cell neoplasia in situ (GCNIS) are accompanied by infiltrating immune cells which are absent in normal spermatogenesis (Nsp). Recent studies provide suggestive evidence that functional polarization and respective subtypes of macrophages (e.g. M1 and M2) play an important role in cancer development and surveillance [1,2,3]. Also for dendritic cells, functionally different subsets (pDC, mDC) have been described . However, this is the first characterisation of immune cells especially macrophage and dendritic cell subsets and to reveal putative immunopathological roles in testicular neoplasia.
Material and Methods: Bouin-fixed, paraffin-embedded tissue samples from human testis (seminoma n=17; GCNIS n=17; Nsp n=12). Antibodies for immunohistochemistry (IHC) and immunofluorescence (IF): macrophages M1: CD68+, CD11c+; M2: CD163+, CD206+; dendritic cells mDC1: CD1c+, CD11c+; mDC2: CD11c+, CD141+; pDC: CD123+, CD303+, CD304+ (DC). Transcripts encoding relevant cytokines and chemokines were measured using quantitative RT-PCR of cryopreserved tissue samples.
Results/ Discussion: Nsp contained CD68+/CD11c- and M2 macrophages. Additionally, we detected M1, M2 and also pDC, mDC in neoplasia. Neoplasia specimen exhibit cytokine and chemokine upregulation TNF-α, IL-12 (M1-related), Il-10, TGF-β (M2-related) and CCL2, CCL5, CCL18, CCL22 transcripts. Interestingly, we observed higher CCL15 level in Nsp and lower level in neoplasia. We propose that CCL15 is a recruitment factor for monocyte-derived macrophages. Thus, CD68+cells can express CCL15-specific receptors such as CCR1 and CCR3. Due to the cytokine milieu which is available in neoplasia, a functional polarization of CD68+cells into M1 or M2 is maybe possible.
Conclusion: Detailed functional characterization of infiltrating immune cells will help to understand the complex mechanisms "immune editing" during testis cancer development. Our focuses are inhibitor treatments of different chemokines and cytokines to control the polarization and recruitment of M1 and M2 to reinforce immune responses that prevent tumour growth.