Tyrosine kinase inhibitor (TKI)-treated chronic myeloid leukemia (CML) patients with increased NK cell number have a better prognosis, and thus, NK cells may suppress CML. However, the efficacy of TKIs varies for reasons yet to be fully elucidated. As NK cell activity is modulated by interactions between their killer cell Ig-like receptors (KIRs) and HLAs of target cells, the combination of their polymorphisms may have functional significance. We previously showed that allelic polymorphisms of KIR3DL1 and HLAs were associated with the prognosis of TKI-treated CML patients. In this study, we focus on differential NK cell activity modulation through KIR3DL1 allotypes. KIR3DL1 expression levels varied according to their alleles. The combination of KIR3DL1 expression level and HLA-Bw4 motifs defined NK cell activity in response to the CML-derived K562 cell line, and Ab-mediated KIR3DL1 blocking reversed this activity. The TKI dasatinib enhanced NK cell activation and cytotoxicity in a KIR3DL1 allotype-dependent manner but did not significantly decrease effector regulatory T cells, suggesting that it directly activated NK cells. Dasatinib also enhanced NK cell cytotoxicity against K562 bearing the BCR-ABL1 T315I TKI resistance-conferring mutation, depending on KIR3DL1/HLA-Bw4 allotypes. Transduction of KIR3DL1*01502 into the NK cell line NK-92 resulted in KIR3DL1 expression and suppression of NK-92 activity by HLA-B ligation, which was reversed by anti-KIR3DL1 Ab. Finally, KIR3DL1 expression levels also defined activation patterns in CML patient-derived NK cells. Our findings raise the possibility of a novel strategy to enhance antitumor NK cell immunity against CML in a KIR3DL1 allotype-dependent manner.Copyright © 2021 The Authors.

Natural killer (NK) cells are becoming valuable tools for cancer therapy because of their cytotoxicity against tumor cells without prior sensitization and their involvement in graft-versus-host disease; however, it is difficult to obtain highly cytotoxic NK cells without adding extra feeder cells. In this study, we developed a new method for obtaining highly cytotoxic NK cells from peripheral blood mononuclear cells (PBMCs) independently of extra feeder cell addition using rituximab not coated on a flask (non-coated rituximab). We found that rituximab could promote both the activation and expansion of NK cells from PBMCs, irrespective of being coated on a flask or not. However, NK cells activated by non-coated rituximab had much greater antitumor activity against cancer cells, and these effects were dependent on autologous living B cells. The antibody-dependent cellular cytotoxicity effect of NK cells activated by non-coated rituximab was also more substantial. Furthermore, these cells expressed higher levels of CD107a, perforin, granzyme B, and IFN-γ. However, there was no difference in the percentage, apoptosis, and cell-cycle progression of NK cells induced by coated and non-coated rituximab. Non-coated rituximab activated NK cells by increasing AKT phosphorylation, further enhancing the abundance of XBP1s. In conclusion, we developed a new method for amplifying NK cells with higher antitumor functions with non-coated rituximab via autologous B cells from PBMCs, and this method more efficiently stimulated NK cell activation than by using coated rituximab.
Copyright © 2021 Niu, Chen, Li, Zhu, Zhou, Xu, Li, Xu, Li, Wang and Cui.

The closely related inhibitory killer-cell immunoglobulin-like receptors (KIR), KIR2DL2 and KIR2DL3, regulate the activation of natural killer cells (NK) by interacting with the human leukocyte antigen-C1 (HLA-C1) group of molecules. KIR2DL2, KIR2DL3 and HLA-C1 are highly polymorphic, with this variation being associated with differences in the onset and progression of some human diseases. However, the molecular bases underlying these associations remain unresolved. Here, we determined the crystal structures of KIR2DL2 and KIR2DL3 in complex with HLA-C*07:02 presenting a self-epitope. KIR2DL2 differed from KIR2DL3 in docking modality over HLA-C*07:02 that correlates with variabilty of recognition of HLA-C1 allotypes. Mutagenesis assays indicated differences in the mechanism of HLA-C1 allotype recognition by KIR2DL2 and KIR2DL3. Similarly, HLA-C1 allotypes differed markedly in their capacity to inhibit activation of primary NK cells. These functional differences derive, in part, from KIR2DS2 suggesting KIR2DL2 and KIR2DL3 binding geometries combine with other factors to distinguish HLA-C1 functional recognition.

Response to tyrosine kinase inhibitors (TKIs) is variable in chronic myeloid leukemia (CML), and elevated natural killer (NK) cells during TKI therapy are positively correlated with superior outcomes. NK cell function involves interactions of their killer immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I on target cells, and the avidity of KIR-HLA interactions depends on the combination of KIR and HLA alleles. We hypothesized that KIR and HLA polymorphisms may influence response to TKIs. KIR and HLA allele genotyping was performed by next-generation sequencing for 76 CML cases, and association with clinical outcome was analyzed. Second-generation TKIs as first-line therapy and patients' sex (female) were strongly associated with achievement of complete molecular response (CMR: MR4.0) after 2 years (P < 0.001 and P = 0.002, respectively). After adjustment for these two characteristics, several KIR alleles remained associated with achievement of MR4.0: KIR2DL4*005/011 or *008 (HR = 1.797, P = 0.032); KIR2DS4*003 or *007/010 (HR = 3.348, P < 0.001); KIR3DL1*005 (HR = 2.746, P = 0.003); and KIR3DL2*009 or *010 [HR = 1.980 (1.109-3.524), P = 0.021]. Strong linkage among these alleles exists, implying that they comprise favorable KIR allele haplotypes. Allelic polymorphisms of KIR3DL1 and HLA-B determine their differential avidity into strong/weak or no interaction. Patients carrying noninteracting KIR3DL1 and HLA-B allele pairs achieved better outcomes than those with strongly interacting pairs, and KIR3DL1*005 associated with a positive outcome among patients with weak-interacting pairs. Thus, KIR3DL1*005 and its associated haplotypes associated with superior TKI therapeutic effects. The combinations of these KIR and HLA alleles may correlate with potent NK cell immunity against CML. Cancer Immunol Res; 6(6); 745-54. ©2018 AACR.
©2018 American Association for Cancer Research.

The aim of the present study was to evaluate the efficacy of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in diagnosing mediastinal and intra-abdominal lymphadenopathies. A total of 154 patients with mediastinal and intra-abdominal lymphadenopathies were included in this retrospective study between February 2010 and March 2015. Malignancy was suspected in the patients as a result of imaging findings and EUS-FNAs were performed to confirm the diagnoses. EUS and EUS-FNA data, as well as hospital medical records, were reviewed. The accuracy of EUS-FNA was 90.8% for diagnosing malignancy and 85.6% for diagnosing benign lymphadenopathy. In combination with flow cytometry (FCM), the accuracy of EUS-FNA to determine lymphoma was 94.2%. Among the malignant lymphadenopathy cases, 80 were caused by metastasis, 19 by lymphoma and 1 by myeloid leukemia. In the 53 benign cases, EUS-FNA revealed a nonspecific inflammatory condition in 27 patients, tuberculosis in 21 patients and Castleman's disease in 5 patients. The factors revealed to be associated with malignant lymphadenopathy included the sex and age of patients, as well as the location and size of the enlarged lymph node. In particular, celiac axis lymphadenopathy was associated with malignancy (23.0% of cases of malignancy, vs. 3.8% of benign lymphadenopathy). EUS-FNA results additionally suggested that the malignant lymph nodes observed in celiac axis were more likely to result from lymphoma (42.1%; 8/19 cases) than metastasis (18.8%; 15/80 cases; P=0.039). By contrast, malignant lymph nodes observed in the mediastinum were more likely to be caused by metastasis (47.5%; 38/80 cases) than lymphoma (10.5%; 2/19 cases; P=0.004). The results of the present study suggested that EUS-FNA is accurate for differentiating between malignancy and benign lymphadenopathy. Therefore, EUS-FNA in combination with FCM analysis, as a minimally invasive and highly sensitive tool, should be routinely performed for the identification of lymphoma. Additionally, examining the enlarged celiac axis lymph nodes of elderly males, who exhibit an increased risk of malignancy, may be beneficial.