Figure 1.
Overall survival based on sIL-2R levels (≤1500 vs. >1500) in DLBCL (A) and FL (B).
Serum sIL-2R levels were analyzed in previously untreated patients with DLBCL (n = 104) or FL (n = 30). The 5-year OS rates for patients with sIL-2R levels of ≤1500 U/ml and >1500 U/ml were 76% and 62%, respectively (p<0.05) in DLBCL, and 100% and 79.3%, respectively (p = 0.189) in FL.
Figure 2.
Representative expression of CD25 (IL-2Rα) on lymphoma cells and normal T-cells in diffuse large B cell lymphoma, follicular lymphoma, and mantle cell lymphoma.
Patient numbers are based on Table 1. Representative cases in diffuse large B cell lymphoma (DLBCL) (A), follicular lymphoma (FL) (B) and reactive lymph node hyperplasia (RLH) (C). There was no apparent association between CD25 expression on lymphoma cells (CD19-positive) or T-cells (CD3-positive) and levels of sIL-2R in these cases.
Table 1.
Relationship between sIL-2R concentrations and expressions of CD25.
Figure 3.
Effects of MMP-9 on cleavage of IL-2Rα.
(A) The ATL cell line, MT4, in which MMP-9 expression was not detected by RT-PCR, was treated with rMMP-9 (1 µg/ml or 3 µg/ml). After 6 h of incubation, analysis of CD25 expression was performed by flow cytometry. (B) MT4 was treated with rMMP-9 (400 ng/ml) or MMP-9 inhibitor (0.1 mM), and cultured in FCS-free medium. After 6 h of culture, experiments were performed in triplicate. P-values of <0.05 were considered to be statistically significant.
Figure 4.
Production of MMP-9 by tumor-associated macrophages.
(A) Positive correlations between sIL-2R and MMP-9 levels were observed in patients with FL (ρ = 0.585, p-value = 0.028), but not in DLBCL. (B) Immunohistochemical staining with anti-MMP-9 antibody in DLBCL, FL and RLH. MMP-9-positive cells were mainly macrophages in each sample, and lymphoma cells were negative for MMP-9 in DLBCL and FL. *Significant correlation was observed.
Figure 5.
Positive correlation between number of CD68-positive macrophages and sIL-2R levels.
We counted the number of CD68- or CD163-positive macrophages in DLBCL, FL and RLH. Representative images of CD68-positive or CD163-positive macrophages in DLBCL and FL are shown (A–D). We also analyzed the correlations between number of CD68-positive macrophages and sIL-2R levels in DLBCL, FL and RLH. Intrafollicular macrophages were counted in FL and RLH. In both DLBCL and FL, the number of CD 68-positive macrophages was higher than that in RLH. (E) In both DLBCL and FL, the number of CD163-positive macrophages was significantly higher than that in RLH. (F) There was a positive correlation between the number of CD68-positive macrophages and sIL-2R levels in FL (right, ρ = 0.5294, p-value = 0.0289) (G). There was also a positive correlation between the number of CD68-positive macrophages and sIL-2R concentrations in extranodal samples of DLBCL. (right, ρ = 0.5891, p-value = 0.0039) (H). *Significant correlations were observed.
Table 2.
Characteristics of analyzed patients and results of immunohistochemical study.
Figure 6.
Model of sIL-2R elevation in B-cell lymphomas.
MMP-9 released from tumor associated macrophages (especially CD68-positive) cleaves the IL-2R α chain on bystander T-cells and B-lymphoma cells, if they express CD25 (IL-2Rα). This mechanism may be involved in elevation of sIL-2R levels in patients with B-cell lymphomas.