# A Comparative Analysis of the Immunoglobulin Repertoire in Leukemia Cells and B Cells in Chinese Acute Myeloid Leukemia by High-Throughput Sequencing

## TL;DR

This study compares the immunoglobulin repertoires in leukemia cells and B cells from Chinese AML patients, revealing distinct patterns that could aid in disease monitoring and treatment.

## Contribution

The study identifies unique V(D)J usage and mutation patterns in AML-Ig, suggesting potential as a biomarker for personalized AML monitoring and therapy.

## Key findings

- AML-Ig showed distinct V(D)J usage and mutation patterns compared to B-Ig in the same patient.
- AML-Ig mutations frequently occurred at post-translational modification sites.
- AML-Ig had a different CDR3 length distribution compared to B-Ig.

## Abstract

It is known that both B cells and myeloblasts from acute myeloid leukemia (AML) express immunoglobulin (Ig). However, the difference between Ig from myeloblasts and B cells has not been explored; therefore, the function and significance of AML-Ig are not well known. Here, we performed 5′ RACE-related PCR coupled with PacBio sequencing to analyze the Ig repertoire of Chinese AML patients. Myeloblasts expressed all five classes of IgH, especially Igγ, with a high expression frequency. Compared with B-Ig in the same AML patient, AML-Ig showed different biased V(D)J usages and mutation patterns. More importantly, mutations of AML-Ig frequently occurred at the sites of post-translational modification. In summary, our results showed that AML-Ig had different sequence characteristics than those of B-Ig and that the unique V(D)J usages of AML-Ig may serve as a novel biomarker for personalized minimal/measurable residual disease monitoring and therapeutic targets in AML patients.

It is common knowledge that immunoglobulin (Ig) is produced by B lymphocytes and mainly functions as an antibody. However, it has been shown recently that myeloblasts from acute myeloid leukemia (AML) could also express Ig and that AML-Ig played a role in leukemogenesis and AML progression. The difference between Ig from myeloblasts and B cells has not been explored. Studying the characteristics of the Ig repertoire in myeloblasts and B cells will be helpful to understand the function and significance of AML-Ig. We performed 5′ RACE-related PCR coupled with PacBio sequencing to analyze the Ig repertoire in myeloblasts and B cells from Chinese AML patients. Myeloblasts expressed all five classes of IgH, especially Igγ, with a high expression frequency. Compared with B-Ig in the same patient, AML-Ig showed different biased V(D)J usages and mutation patterns. In addition, the CDR3 length distribution of AML-Ig was significantly different from those of B-Ig. More importantly, mutations of AML-IgH, especially Igμ, Igα, and Igδ, were different from that of B-IgH in each AML patient, and the mutations frequently occurred at the sites of post-translational modification. AML-Ig has distinct characteristics of variable regions and mutations, which may have implications for disease monitoring and personalized therapy.