Inhibitory leucocyte immunoglobulin-like receptor B4 (LILRB4): a promising prognostic marker in acute lymphoblastic leukemia

Inhibitory leucocyte immunoglobulin-like receptor B4 (LILRB4) is an inhibitory receptor essential for immune checkpoint pathways. LILRBs are immunological checkpoint factors because their immune-suppressive effect is comparable to that of cytotoxic T‑lymphocyte-associated antigen 4 (CTLA4) and programmed death 1 (PD-1). LILRBs and a similar immunoreceptor tyrosine-based inhibitory motifs (ITIM)-containing receptor LAIR1 are expressed on and promote tumor growth in hematological and solid cancer cells.

To measure serum LILRB 4 levels in the peripheral blood of acute lymphoblastic leukemia (ALL) patients and determine its correlation with clinical outcome and disease prognosis.

This study included 60 newly diagnosed ALL patients between the ages of 18 and 55 eligible for chemotherapy, as well as 30 matched healthy control subjects. The serum LILRB4 concentration was measured using ELISA kits.

Serum LILRB4 level was statistically significantly higher in ALL patients than in healthy controls (1760 ng/L ± 541.208 standard deviation [SD] vs 175.833 ng/L ± 47.88 SD, P value < 0.0001). Positive minimal residual disease (MRD) after induction chemotherapy was associated with higher serum LILRB4 levels than negative MRD (p = 0.038; 1930.55 vs. 1582.14, respectively). Patients who experienced higher serum LILRB4 levels reported high relapse rates (2175 vs. 1748.68, with a p-value of 0.033).

Acute lymphoblastic leukemia patients had higher LILRB4 levels than healthy controls. Patients with positive MRD after induction had higher serum LILRB4 levels than those with negative residual disease. Patients who experienced higher serum LILRB4 levels reported high relapse rates. Therefore, LILRB4 level in ALL patients can be considered a predictor for relapse.