Alloreactive NK-cells activity to leukemia with HLA-LOH after HLA haplomismatch stem cell transplantation

我们用位点特异性抗体的流式细胞术研究了白血病患者在诊断时和造血干细胞移植(HSCT)后复发患者的白血病原始细胞上的人类白细胞抗原的表达。HL A表达分析有助于分析供者嵌合体和微小残留病。我们发现，供者NK细胞能有效地杀伤复发的带有HLA-LOH的白血病细胞。这部分是因为白血病细胞表面的ULBP2在具有HLA-LOH的白血病细胞上高度表达。我们可以监测单个KIR阳性的NK细胞，这些细胞不受患者的人类白细胞抗原的抑制。单个KIR阳性NK细胞增多与NK细胞同种异体反应性增高有关。最后，用FDA批准的基因修饰的K562细胞建立GMP级NK细胞扩增方法。这些发现可能为使用KIR不相合的供者NK细胞进行异基因NK细胞治疗奠定了基础。

We investigated HLA expression on leukemic blasts derived from patients at diagnosis and relapse after hematopoietic stem cell transplantation (HSCT) using flow cytometry with locus-specific antibodies. HLA expression analysis was useful for analysis of donor chimerism and minimal residual diseases. We found that leukemic blasts with HLA-LOH at relapse were efficiently killed by donor NK cells. This was partially explained because ULBP2 on the leukemic blasts with HLA-LOH was highly expressed. We could monitor single KIR positive NK cells that are not inhibited by patient's HLA. Increased single KIR positive NK cells were related to higher NK cell alloreactivity. Finally, GMP grade NK cell expansion method was established using FDA approved gene modified K562 cells. These findings could establish the rationale of allogeneic NK cell therapy using KIR mismatched donor NK cells.