Expression of CCR5 receptors on Reed–Sternberg cells and Hodgkin lymphoma cell lines: Involvement of CCL5/Rantes in tumor cell growth and microenvironmental interactions

Abstract

The expression of CCL5/Rantes by Hodgkin (H) and Reed‐Sternberg (RS) cells has been recently documented. In the present study we demonstrated that the CCL5 receptor (CCR5) is constitutively expressed by Hodgkin Lymphoma (HL)‐derived cell lines (i.e. L‐428, KM‐H2, L‐1236 and L‐540) as shown by immunohistochemistry, flow cytometry and western blotting and also detected by immunohistochemistry on primary H‐RS cells from lymph node tissues. sCD40L never significantly affected CCR5 expression, whereas a short exposure to doxorubicin down regulated its expression. CCR5 receptors on HL cell lines were functionally active, since neutralizing anti‐CCL5 monoclonal antibodies inhibited basal proliferation of HL‐derived cell lines and recombinant CCR5 ligands (CCL3/Mip‐1α, CCL4/Mip1β and CCL5/Rantes) increased their clonogenic growth. CCL5 secretion by L‐1236, L‐428 and KM‐H2 cells was stimulated by CD40 engagement and also by coculturing L‐1236 cells on primary stromal fibroblasts from HL‐involved lymph nodes (HLF). Coculture experiments indicated that a direct contact of H‐RS cells induces HLF cells to produce CCL5. Supernatants from L‐1236, L‐428 and KM‐H2 cells stimulated migration of purified CD4+ T‐cells and eosinophils in vitro. The migratory response to HL‐cell lines supernatants was only partially neutralized (CD4+ cells: 70%; esinophils: 36%) by anti‐CCL5 antibodies, reinforcing the notion that multiple chemokines are involved in the recruitment of nonmalignant reactive cells in HL tissues. Taken together, our results indicate a possible involvement of the CCR5/CCR5‐ligands signaling in the regulation of H‐RS cells growth and in the formation/maintenance of the typical tissue microenvironment of HL.