Anti-myelocytomatosis tag antibody detects myelocytomatosis oncogene expression in Burkitt lymphoma

Abstract

Background: The immunohistochemical (IHC) detection of myelocytomatosis oncogene (MYC) is a crucial step in the diagnosis and prognosis of Burkitt lymphoma (BL). Sections of the MYC protein are routinely used as tags in protein precipitation experiments to assist with the isolation of proteins without antibodies. However, it is unknown if the tag antibodies can also be used for BL diagnosis.

Aim: This project aimed to determine whether the MYC tag 9E10 antibody can be used to detect MYC overexpression because of MYC translocation in BL cases.

Setting: Charlotte Maxeke Johannesburg Academic Hospital, South Africa.

Methods: Immunohistochemical staining for 9E10 was optimised and used to stain 10 BL with known MYC translocation status to calculate sensitivity, specificity and predictive values.

Results: Staining of the BL cases generally produced a ‘very weak’ (70%) and weak-moderate (18.2%) staining patterns with a staining extent of 1+ (36%) and 3+ (27%). Of the 10 samples, 6 (60%) showed a positive MYC protein expression by IHC. In comparison, 7 (70%) samples indicated MYC gene rearrangements. There were 5 (50%) cases with both MYC IHC expression and gene translocations and 2 (20%) cases that were negative for both MYC IHC and gene rearrangements.

Conclusion: The authors demonstrate that the 9E10 MYC tagged antibody may be used to detect MYC gene expression with a sensitivity of 71% and a specificity of 67%. In addition, the positive predictive value (PPV) and negative predictive value (NPV) varied according to IHC staining cut-offs. Immunohistochemical expression does not perfectly correlate with translocation status because of inconsistencies with IHC interpretation.

Contribution: MYC gene rearrangements are present in nearly all BL cases. Finding more affordable and convenient ways to predict the presence of MYC gene rearrangements is of utmost importance, given the lack of financial resources in our continent. This study shows that the 9E10 antibody, commonly used in protein tagging experiments, may also be used to predict MYC gene rearrangements in BL.