Contributions
Abstract: PB2073
Type: Publication Only
Background
Epstein–Barr virus (EBV) infects more than 90% of the population worldwide. The virus has evolved to persist life-long in B-lymphocytes of infected individuals, but disruption of this tightly regulated B-cell infection could result in EBV-associated B cell lymphomas. In Argentina, primary infection is mostly subclinical and 90% of patients are seropositive by 3 years old. However, EBV presence is statistically associated with Hodgkin lymphoma (HL) and Diffuse Large B cell lymphoma (DLBCL) in patients younger than 10 years, suggesting a relationship between low age of EBV infection and B-cell lymphoma development in children from Argentina.
Aims
Given that viral latent proteins and microenvironment composition play a key role in tumor pathogenesis or control of viral infection, our aim was to compare this scenario in pediatric EBV-associated lymphomas derived from the germinal center (GC) and post-GC with the same areas in tonsils from pediatric EBV carriers, to investigate whether an alteration of microenvironment could be related to lymphomagenesis
Methods
Formalin fixed paraffin embedded (FFPE) pediatric biopsy samples from 26 DLBCL, 55 HL and 41 tonsils from EBV carriers were analyzed. Immunohistochemistry for LMP1, EBNA2, CD4, CD8, Foxp3 and GrB was performed, together with EBERs in situ hybridization, and positive cells were counted in the EBV+ milieu.
Results
Latency II pattern (LMP1+ EBNA2-) was predominant in HL (100%), DLBCL (55%), as well as in EBV+ CG in pediatric carriers (90%). CD4+ cell count displayed no differences between EBV+ and EBV- HL or DLBCL (p>0.05, Mann Whitney test), whereas statistically higher CD4+ cells were counted at the EBV+ GC in pediatric carriers (p=0.014, Mann Whitney test). On the other hand, CD8+ cells did not exhibit statistical differences neither in EBV-associated lymphomas nor in benign conditions at the CG, and the same was observed for Foxp3 regulatory cells (p>0.05, Mann Whitney test). In contrast, CD8+ cell count were statistically higher exclusively at EBV+ subepithelial region in tonsils, compared to EBV- counterpart (p=0.0039, Mann Whitney test). Finally, cytotoxic activity evaluated by GrB expression displayed a trend to higher mean in EBV+ DLBCL (p=0.057, Mann Whitney test) but no in HL. Concerning EBV, pediatric carriers did not shown differences in cytotoxic activity according to EBV presence at the CG (p>0.05, Mann Whitney test). In fact, GrB cytotoxic activity was prevalent only at the EBV+ subepithelial region (p= 0.0420, Mann Whitney test).
Conclusion
Latency II pattern prevails in both pediatric EBV-associated lymphomas and in EBV+ GC from carriers, indicating that LMP1expression may collaborate in the lymphomagenesis process at the GC in pediatric patients from our country. Cytotoxic activity against EBV infection may be only relevant in pediatric DLBCL, and in EBV+ subepithelial regions in pediatric carriers, whereas in EBV+ HL is not increased, in contrast to previously described. CD4+T helper cell response plays a key role at the GC region in EBV carriers, by participating directly as effectors cells, by helping to the overall immune response in the control of viral infection and restrict latency expression to type II pattern, and, ultimately, by limiting the cell outgrowth. Failure in this process may trigger malignant transformation in EBV-associated lymphomas.
Session topic: 18. Non-Hodgkin & Hodgkin lymphoma - Biology
Keyword(s): Pediatric, Microenvironment, EBV, B cell lymphoma
Abstract: PB2073
Type: Publication Only
Background
Epstein–Barr virus (EBV) infects more than 90% of the population worldwide. The virus has evolved to persist life-long in B-lymphocytes of infected individuals, but disruption of this tightly regulated B-cell infection could result in EBV-associated B cell lymphomas. In Argentina, primary infection is mostly subclinical and 90% of patients are seropositive by 3 years old. However, EBV presence is statistically associated with Hodgkin lymphoma (HL) and Diffuse Large B cell lymphoma (DLBCL) in patients younger than 10 years, suggesting a relationship between low age of EBV infection and B-cell lymphoma development in children from Argentina.
Aims
Given that viral latent proteins and microenvironment composition play a key role in tumor pathogenesis or control of viral infection, our aim was to compare this scenario in pediatric EBV-associated lymphomas derived from the germinal center (GC) and post-GC with the same areas in tonsils from pediatric EBV carriers, to investigate whether an alteration of microenvironment could be related to lymphomagenesis
Methods
Formalin fixed paraffin embedded (FFPE) pediatric biopsy samples from 26 DLBCL, 55 HL and 41 tonsils from EBV carriers were analyzed. Immunohistochemistry for LMP1, EBNA2, CD4, CD8, Foxp3 and GrB was performed, together with EBERs in situ hybridization, and positive cells were counted in the EBV+ milieu.
Results
Latency II pattern (LMP1+ EBNA2-) was predominant in HL (100%), DLBCL (55%), as well as in EBV+ CG in pediatric carriers (90%). CD4+ cell count displayed no differences between EBV+ and EBV- HL or DLBCL (p>0.05, Mann Whitney test), whereas statistically higher CD4+ cells were counted at the EBV+ GC in pediatric carriers (p=0.014, Mann Whitney test). On the other hand, CD8+ cells did not exhibit statistical differences neither in EBV-associated lymphomas nor in benign conditions at the CG, and the same was observed for Foxp3 regulatory cells (p>0.05, Mann Whitney test). In contrast, CD8+ cell count were statistically higher exclusively at EBV+ subepithelial region in tonsils, compared to EBV- counterpart (p=0.0039, Mann Whitney test). Finally, cytotoxic activity evaluated by GrB expression displayed a trend to higher mean in EBV+ DLBCL (p=0.057, Mann Whitney test) but no in HL. Concerning EBV, pediatric carriers did not shown differences in cytotoxic activity according to EBV presence at the CG (p>0.05, Mann Whitney test). In fact, GrB cytotoxic activity was prevalent only at the EBV+ subepithelial region (p= 0.0420, Mann Whitney test).
Conclusion
Latency II pattern prevails in both pediatric EBV-associated lymphomas and in EBV+ GC from carriers, indicating that LMP1expression may collaborate in the lymphomagenesis process at the GC in pediatric patients from our country. Cytotoxic activity against EBV infection may be only relevant in pediatric DLBCL, and in EBV+ subepithelial regions in pediatric carriers, whereas in EBV+ HL is not increased, in contrast to previously described. CD4+T helper cell response plays a key role at the GC region in EBV carriers, by participating directly as effectors cells, by helping to the overall immune response in the control of viral infection and restrict latency expression to type II pattern, and, ultimately, by limiting the cell outgrowth. Failure in this process may trigger malignant transformation in EBV-associated lymphomas.
Session topic: 18. Non-Hodgkin & Hodgkin lymphoma - Biology
Keyword(s): Pediatric, Microenvironment, EBV, B cell lymphoma