Multiple Defects Impair the HLA Class II Antigen Presentation Capacity of Burkitt Lymphoma

Burkitt lymphoma (BL) is a B-cell malignancy which occurs with varying clinical manifestations and frequencies. The most well-known presentation of BL is found in areas which are holoendemic or hyperendemic for malaria. This endemic BL occurs primarily in children and presents as tumors of the jaw [1,2]. Though a strong association exists between endemic BL and malaria, the nature of the relationship remains unclear. A sporadic form of BL also occurs elsewhere in the world and typically causes tumors in the gut and upper respiratory tract [3]. There are various other contributing factors which may lead to development of BL, including Epstein-Barr Virus (EBV) and Human Immunodeficiency Virus (HIV) [4,5]. EBV has long been associated with development of BL and is found in nearly all cases of endemic BL but, in spite of intense research, the relationship between EBV and BL remains unclear. It is generally believed that infection with EBV somehow drives transformation which then leads to development of BL [6]. While the exact cause of BL has remained elusive (and is likely multi-factorial) the hallmark of all BL is the constitutive activation of the MYC gene resulting in its overexpression and cell transformation [7,8]. Most commonly, this occurs through translocation of the MYC gene to an immunoglobulin locus, which in B cells would result in constitutive expression [8]. Though translocation of MYC was long considered a diagnostic criterion for BL, recent evidence suggests other mechanisms may be responsible for MYC deregulation in a small percentage of BL cases [9].