Background:
Diffuse large B-cell lymphoma (DLBCL) has been the most frequent form of non-Hodgkin lymphoma (NHL), accounting for roughly 24% of new instances per year. High mobility group box 1 protein is a nuclear DNA-binding protein that was discovered more than 30 years ago. It binds to DNA and functions as a cofactor for gene transcription . Overexpression of HMGB1 was being discovered in many cancers, including breast cancer , gastric cancer , and non-Hodgkin lymphoma.

Aim of the work:
to evaluate the effect of diffuse large B cell lymphoma on high mobility group box 1 protein level and how chemotherapy affects its level in patients with DLBCL.

Patients and methods:
This study was carried out at Al-Hussein university hospital. Patients were divided into two groups ,Group (A): composed of 35 patients with DLBCL for whom pre-treatment and post-treatment level of HMGB1 protein were measured. Group (B): composed of 35 normal subjects act as a control group . All procedures followed Al-Azhar University Ethical Committee regulations.

Results:
there is statistically significant improvement after chemotherapy as t value equaled 8.632 with P-value 0.000. Also, when comparing pre-value with normal, paired t test equaled 10.16 with p value 0.000. Using ROC curve, it was stated that area under the curve equaled 1 with standard error 0 and P=0.017.

Conclusion:
High mobility group box 1 protein is a significant indicator in patients with Diffuse large B-cell lymphoma .