Altered Expression of NK Receptors in Racially/Ethnically Diverse and Risk-of-Relapse Pediatric Acute Lymphoblastic Leukemia Patients.

Acute Lymphoblastic Leukemia (ALL) is a cancer that predominantly affects white blood cells within the blood and bone marrow of adults and children. Currently, ALL is one of the most prevalent malignancies in pediatric patients and is most seen among Caucasian and Hispanic descent, with lower incidence in African American children. The goal of the study was to investigate the expression of immune cell receptors in racial/ethnic populations and risk factors for relapse that could potentially influence the pediatric ALL outcomes. Twenty healthy subjects and forty-two pediatric ALL subjects were enrolled in the study and whole-blood was collected at diagnosis and post-chemotherapy, and the cell surface expression of various immune receptors, including 2B4, CS1, LLT1, Nkp30, and NKp46, was determined by flow cytometry. Very high-risk and high-risk of relapse ALL subjects showed increased expression of LLT1 on NK cells, T cells, and monocytes at diagnosis compared to healthy subjects. CS1 was also significantly overexpressed on monocytes of very-high risk ALL subjects both at diagnosis and after the end of chemotherapy as compared to healthy subjects. Also, there was a significantly increased expression of NKp30 on T cells of Caucasians as compared to Hispanics and African Americans at diagnosis, and downregulation of CS1 and LLT1 on T cells of Caucasians post-induction chemotherapy. The altered expression of immune receptors in racial/ethnic and risk stratified groups may provide insights into the immune surveillance mediated by T cells and NK cells against pediatric ALL.