Induction of interdigitating reticulum cell-like differentiation in human monocytic leukemia cells by conditioned medium from IL-2-stimulated helper T-cells
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Published on: November 11, 2016
K Takahashi1, K Miyatani, H Yanai
1Department of Pathology, Okayama University Medical School, Japan.
Insights
Helper T-cells influence monocytic leukemia cells, promoting differentiation into dendritic cell-like cells. This suggests T-cells are crucial for interdigitating reticulum cell development in lymphoid tissues.
Area of Science:
- Immunology
- Cell Biology
- Hematology
Background:
- Monocytic leukemia (MoL) cells exhibit diverse morphologies, with some resembling interdigitating reticulum cells (IDC) and others being purely monocytic.
- Interdigitating reticulum cells (IDC) are crucial accessory cells in T-cell zones of lymphoid tissues.
Observation:
- MoL cells treated with conditioned medium from a CD4+ T-cell line developed dendritic projections and expressed markers like HLA-DR, S-100 beta, and CD1.
- Phagocytic activity and lysosomal enzyme levels (lysozyme, esterase) were reduced in treated MoL cells.
- CD14 antigen expression decreased, while accessory cell function in mixed leukocyte reactions (MLR) increased.
Findings:
- A novel ~31 kDa protein factor in T-cell conditioned medium induces MoL cells to acquire IDC-like features.
- This factor down-regulates CD14 expression and enhances allogeneic MLR.
- The study identifies a soluble factor from helper T-cells that drives monocytic differentiation.
Implications:
- These findings support a close relationship between IDC and the monocytic lineage.
- Helper T-cells play a critical role in shaping the microenvironment for IDC differentiation and maturation.
- This research sheds light on the cellular interactions governing lymphoid tissue architecture and immune responses.
Abstract:
Monocytic leukemia (MoL) cells were obtained from the peripheral blood of a patient in whom the leukemic cells infiltrating various lymphoreticular organs exhibited features intermediate between interdigitating reticulum cells (IDC) and ordinary phagocytic macrophages, whereas the leukemic cells in the peripheral blood were essentially monocytic and lacked such features. Peripheral blood CD4+ T-cells were established as an interleukin-2-dependent T-cell line. When the MoL cells were exposed for a few days to conditioned medium from the T-cell line, they extended several dendritic cytoplasmic projections and became intensely positive for HLA-DR antigen, cytoplasmic S-100 beta protein, and CD1 antigen. Functionally, the conditioned medium significantly down-regulated Fc-mediated and Fc-independent phagocytic activities, and the levels of lysosomal enzymes such as lysozyme and nonspecific esterase in the MoL cells. Moreover, the conditioned medium significantly up-regulated the accessory cell function of the MoL cells as measured by the primary allogenic mixed leukocyte reaction (MLR). Furthermore, the conditioned medium significantly down-regulated the expression of CD14 antigen. Biochemical analysis indicated that the factor responsible for these changes is a protein which is distinct from known human cytokines and whose molecular weight is approximately 31 kDa. These findings suggest that IDC are closely related the monocytic lineage and that helper T-cells play an important role in constructing the microenvironment of T-lymphoid tissues which is necessary for the differentiation and maturation of IDC.
