Discovery explains how immune cells target DNA mutations to improve antibodies

October 1, 2026
10:13 pm

Scientists at the Montreal Clinical Research Institute (IRCM), led by Université de Montréal medical professor Javier Di Noia, have shed light on a fundamental mystery in immunology: How do immune cells manage to concentrate a powerful mutagenic enzyme at precisely defined regions of DNA while largely sparing the rest of the genome from potentially dangerous damage?

Published in the journal Nature, the new research reveals the crucial role of two proteins, MLLT1 and MLLT3, which act as key “gatekeepers” of the activity of the enzyme AID (activation-induced cytidine deaminase). The discovery could help scientists better understand how certain lymphomas and leukemias develop and potentially pave the way for new therapeutic strategies.

Balancing protection and risk

To fight infections effectively, B cells—key cells of the immune system—must produce a vast diversity of antibodies. To achieve this, they deliberately modify their own DNA using the enzyme AID, which introduces mutations into antibody genes to improve their effectiveness.

Discovery explains how immune cells target DNA mutations to improve antibodies

Balancing protection and risk

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