The Prognostic Significance of Tumor-Associated Macrophages and NK Cells in Patients with Diffuse Large B-Cell Lymphoma Treated with RCHOP

Background

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL). Although international prognostic index (IPI) has been widely used in DLBCL to evaluate the prognosis, there is need to find new biomarkers to predict outcome. Tumor microenvironment has been reported to be associated with both metastatic spread and diminished in some tumors. Tumor-associated macrophages (TAMs) and nature-killer (NK) cells play an important role in the tumor microenvironment. Therefore, we performed this study to investigate the prognostic implications of TAMs including M1 as well as M2 and NK cells in DLBCLs.

Materials and Methods

We reviewed 77 cases of DLBCL diagnosed between June 2004 and October 2012, who treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP). Patients were divided into GCB and non-GCB subgroups by Hans’ algorithm. We performed immunohistochemical stains using CD68, CD163 and CD57 to mark M1 macrophages, M2 macrophages and NK cells on paraffin tissue section. The percentage of TAMs was recorded and graded as: 0 if less than 5%, 1 if 5-25%, and 2 if greater than 25% of the total cells present in tumor cells rich nodules were positive for CD68 or CD163. And counting the mean number of the CD57+ cells in 5 fields under high-power magnification (400 times): 0 if less than 5 positive cellsG1 if more than 5 positive cells.

Results

Of the 77 DLBCL patients treated with R-CHOP, there were 51 males (66.2%), 26 females (33.8%). The median age was 52 years (range, 16-81 years). The median follow-up was 38.1 months. The median percentage for CD68 was 12.8 %( range, 2.4–50.84), for CD163 was 12.3 %( range, 1.0–39.2). The median counts of CD57 cells were 5 (range, 1.0-78) per unit area. In univariate analysis, an increase in CD68-positive cells was related to improved EFS (grade 0 vs. grade 2, p = 0.036). By contrast, an increased number of CD163-positive cells were significantly poor associated with OS, (grade0 vs grade2, p = 0.033). Patients with elevated NK cells tended to have no effect on prognosis. In multivariate analysis, an increased CD68 -positive cells was an independent predictors of EFS (HR 0.467, 95%CI 0.236-0.922, P=0.028), an decreased CD163-positive cells and lower LDH were independent predictors for OS (HR 2.287, 95%CI 1.043-5.013, P=0.039).

Conclusion

These results suggest that M1 macrophages might predict favorable clinical outcome and M2 macrophages predict poor clinical outcome. However, the NK cells have no prognostic significance in DLBCL patients treated with RCHOP.