Children with endemic Burkitt lymphoma are deficient in EBNA1-specific IFN-γ T cell responses

Endemic Burkitt lymphoma (eBL) is the most common childhood cancer in equatorial Africa and is linked to Epstein-Barr virus (E B V) and Plasmodium falciparum coinfections early in life. Epstein-Barr nuclear antigen I (EBNA1) is the sole viral latent antigen expressed in BL tumors. Loss of EBNA1-specific immune surveillance could allow eBL emergence. Therefore, EBNA1-specific T cell responses were analyzed by IFN-gamma ELISPOT in Kenyan children with eBL and compared to healthy children with divergent malaria exposure. Significantly fewer children with eBL, 16% (7/44) had EBNA1-specific IFN-gamma responses in contrast to healthy children living in a malaria holoendemic area or in an area with sporadic malaria transmission, 67% (40/60) and 72% (43/60) responders, respectively (p < 0.003). Children with eBL maintained IgG(1) dominated antibody responses to EBNA I similar to healthy children suggesting a selective loss of IFN-gamma secreting EBNA1-specific T cells in the presence of intact Immoral immunity. CD8(+) T cell responses to EBV lytic and latent antigens not expressed in the tumors were similarly robust in eBL, patients compared to healthy children. In addition, CD4(+) T cell responses to a malaria protein, merozoite surface protein 1, were present in lymphoma patients. This study demonstrates a selective loss of EBNA1-specific T cell responses in children with eBL and suggests a Potential immunotherapeutic target for this EBV-associated lymphoma. (C) 2008 Wiley-Liss. Inc.