Early Macrophage and Mast Cell Responses in Diffuse Large B-Cell Lymphoma After Immunochemotherapy

Abstract

5206 Background: The prognostic impact of tumor microenvironment on the survival of lymphoma patients has recently been reported. However, early molecular and cellular responses to immunochemotherapy are unknown. Here, we have compared the tumor-associated macrophage (TAM) and mast cell (MC) contents in the lymphoma tissue in vivo before and after the first immunochemotherapy course in a small cohort of aggressive B-cell lymphoma patients. Patients and methods: The population of this pilot study consisted of seven diffuse large B-cell lymphoma (DLBCL) and three grade IIIB follicular lymphoma (FL) patients treated with rituximab in combination with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone)-like regimen (immunochemotherapy). Paired tumor samples were collected before and a day after the first course of therapy, and evaluated immunohistochemically for CD68+, CD163+ macrophages and tryptase+ MCs. Freshly frozen lymphoma tissue containing enough material for paired mRNA analyses was available from 8 patients. Results: Comparing pre- and post-treatment tissue samples, an increase in the number of CD68+ TAMs was observed (p=0.023), whereas no variation in MC contents was found. If the patients were grouped according to response, i.e. remission (n=7) vs relapse (n=3), the most significant increase after therapy was observed in M2-type CD163+ TAM content (p=0.001). In the exon array analyses, the mRNA levels of both CD68 (p=0.052) and CD163 (p=0.023) genes increased after therapy. Conclusions: Our preliminary data suggest significant changes in macrophage content and their relative subsets in the lymphoma microenvironment after the first course of immunochemotherapy. Disclosures: No relevant conflicts of interest to declare.