Anti-CD14 monoclonal antibody, clone NJM-3

Background: Most tumors responding to immunotherapy with monoclonal antibodies targeting programmed cell death protein1 (PD1) and programmed death ligand-1 (PD-L1) show surface expression of PD-L1. Neuroblastoma has been reported to show low PD-L1 surface expression. Methods: The effect of immune checkpoint inhibitor on mouse neuroblastoma was investigated, and host immune cells were analyzed in the tumor microenvironment. Expression of co-stimulatory molecules by Neuro-2a mouse neuroblastoma cells was analyzed using flow cytometer. Neuro-2a cells were inoculated subcutaneously into A/J mice, followed by intraperitoneal injection of antibodies targeting PD-1 and PD-L1. Mice were sacrificed for the measurement of tumor weights on day 14 following tumor inoculation, and tumor-infiltrating cells were analyzed using a flow cytometer. Results: Dim expression of PD-L1 was observed on the cell surface of cultured Neuro-2a cells. Growth of subcutaneous tumors was significantly suppressed, and PD-L1 expressing tumor cells were depleted by the antibody treatment. We confirmed that Neuro-2a cells opsonized by the anti-PD-L1 antibody were phagocytosed in the in vitro setting. In the treated tumor microenvironments, CD8a(+) lymphocyte and CD11c(+) MHC II+ cells were significantly accumulated in comparison with the control group. These CD11c(+) MHC II+ cells expressed CD80, CD86, CD14, and CD40, but not CD205, PD-L1, or CTLA4. PD-1 expression was detected dimly. Immune suppressive effects of CD11b(+) Gr-1(+) myeloid-derived suppressor cells by the administration of anti-PD-1 and PD-L1 antibodies were not observed in spleen, regional lymph nodes, or tumor microenvironment. Conclusions: Our findings raise the possibility that co-administration of anti-PD-1 and antiPD-L1 antibodies have a synergistic effect on inhibition of tumor growth and could be an effective therapy against neuroblastoma with dim expression of PD-L1. (C) 2020 Elsevier Inc. All rights reserved.

Monocytes contribute to immune responses as a source for subsets of dendritic cells and macrophages. Human blood monocytes are classified as classical, non-classical and intermediate cells. However, the particular functions of these subsets have been hard to define, with conflicting results and significant overlaps. One likely reason for these ambiguities is in the heterogeneity of these monocyte subsets regrouping cells with divergent functions. To better define monocyte populations, we have analysed expression of 17 markers by multicolour flow cytometry in samples obtained from 28 control donors. Data acquisition was tailored to detect populations present at low frequencies. Our results reveal the existence of novel monocyte subsets detected as larger CD14(+) cells that were CD16(+) or CD16(neg). These large monocytes differed from regular, smaller monocytes with respect to expression of various cell surface molecules, such as FcR, chemokine receptors, and adhesion molecules. Unsupervised multidimensional analysis confirmed the existence of large monocytes and revealed interindividual variations that were grouped according to unique patterns of expression of adhesion molecules CD62L, CD49d, and CD43. Distinct inflammatory responses to TLR agonists were found in small and large monocytes. Overall, refining the definition of monocyte subsets should lead to the identification of populations with specific functions.