CD56+, NKp46+ cell line (MZ93) expressing T-cell and myeloid antigens

NKp46 regulates the production of serine proteases and IL-22 in human mast cells in urticaria pigmentosa

NKp46 (natural cytotoxic receptor 1/CD335) is expressed on natural killer cells and Th2-type innate lymphocytes. However, NKp46 expression in human mast cells has not yet been reported. Here, we explored the expression of, and possible role played by, NKp46 in such cells. NKp46 protein was expressed in human mast cells in urticaria pigmentosa principally of the tryptase-positive/chymase-negative type (MCT), but not in human non-neoplastic skin mast cells of the tryptase-positive/chymase-positive (MCTC) type. NKp46 expression was also evident in the human neoplastic mast cell line HMC1.2. NKp46 knockdown changed the phenotype of this cell line from MCT to MCTC and downregulated GrB production, but did not influence IL-22 production. An agonistic anti-NKp46 antibody upregulated production of GrB and IL-22, but did not change the MCT-like phenotype of HMC1.2 cells. NKp46 was thus involved in the production of serine proteases and IL-22 in human mast cells.

Expression of natural cytotoxicity receptors NKp30, NKp44, and NKp46 mRNAs and proteins by human hematopoietic and non-hematopoietic cells

T-cells and NK cells arise from common pluripotent stem cells, with shared early developmental pathway and surface markers. Distinguishing between them is becoming difficult, but critical for study. A large family of NK cells, including classical NK, NK-T, and NK-CTL exists. Natural cytotoxicity receptors (NKp46, NKp44, NKp30) have been proposed as specific for classical NK cells, but were expressed at protein and mRNA level by CD8+NK/T cell line SRIK-NKL, suggesting more widespread expression. We investigated and found expression of these markers at the protein and mRNA level in multiple human cell lines.

Fc epsilon RI and CD22 mRNA are expressed in early B-lineage and myeloid leukemia cell lines

CD22, one of the important markers for diagnosing B-lineage acute leukemia, was expressed in mature basophil granulocytes. We then investigated the expression of CD22 and other B cell- and basophil-related molecules in 25 human acute leukemia cell lines to find the phenotype of the virtual common progenitor of B and myeloid lineage. Surface and cytoplasmic expressions of antigens were analyzed using a flow cytometer and an essential antibody panel used for diagnosing acute leukemia as well as cytokine receptors and basophil-related enzymes. Messenger RNA expression of Fc epsilon R1 and CD22 was also analyzed. Peroxidase-positive and -negative myeloid leukemias showed eosinophil- and basophil-type expression of enzymes, respectively. Early myeloid and B-lineage cells expressed basically similar combinations of cytokine receptors and various combinations of mRNA listed above, while T-lineage cells did not. The virtual common progenitor of B and myeloid lineage cells may be defined as immature cells simultaneously expressing B and basophil phenotypes.