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Updated: Jun 10, 2026
A Novel Feeder-free System for Mass Production of Murine Natural Killer Cells In Vitro
Published on: January 9, 2018
Unidirectional signaling triggered through 2B4 (CD244), not CD48, in murine NK cells
Eun-Ok Kim1, Nayoung Kim, Tae-Jin Kim
1Global Research Lab, Department of Biochemistry and Division of Brain Korea 21 Program for Biomedical Science, Graduate School of Medicine, Korea University College of Medicine, Seoul, Korea.
Insights
The interaction between 2B4 (CD244) and CD48 on immune cells primarily stimulates 2B4, enhancing NK cell functions. CD48 acts as a ligand, not a primary stimulator, in these interactions.
Area of Science:
- Immunology
- Cellular immunology
- NK cell biology
Background:
- The 2B4 (CD244) and CD48 receptor-ligand pair modulates Natural Killer (NK) cell activity.
- Interactions can occur between NK cells or between NK cells and other hematopoietic cells.
- CD48 has also been identified as an activating receptor, raising questions about bidirectional signaling.
Purpose of the Study:
- To investigate the functional consequences of 2B4-CD48 engagement on NK cell activity.
- To determine whether CD48 ligation on target cells or direct CD48 cross-linking on NK cells impacts NK cell functions.
- To clarify the primary role of CD48 in 2B4-mediated signaling.
Main Methods:
- Utilized target cells (EL4 and P815) engineered to express 2B4 or CD48.
- Employed direct cross-linking of NK cells with plate-bound anti-CD48 or anti-2B4 monoclonal antibodies.
- Assessed NK cell cytotoxicity, proliferation, and cytokine production.
Main Results:
- Ligation of CD48 on target cells by 2B4+ NK cells did not significantly alter NK cell cytotoxicity or proliferation.
- Direct cross-linking of NK cells with anti-CD48 mAb did not modulate proliferation, cytotoxicity, or cytokine production.
- Cross-linking of NK cells with anti-2B4 mAb consistently enhanced NK cell proliferation and effector functions.
Conclusions:
- CD48 on surrounding NK or non-NK cells primarily functions as a ligand that stimulates the 2B4 receptor on adjacent NK cells in mice.
- The 2B4 receptor is the main driver of enhanced NK cell proliferation and effector functions in this interaction.
- Bidirectional signaling through CD48 as an activating receptor in this context is not supported by the findings.
Abstract:
Engagement of 2B4 (CD244) with CD48 results in activation, costimulation, or inhibition of NK cell activities, depending on the cell types and the stage of differentiation. In vivo, 2B4+ NK cells can interact with CD48+ NK cells and also with surrounding CD48+ hematopoietic cells. Similarly, CD48+ NK cells may be triggered by adjacent 2B4+ NK cells or other hematopoietic cells expressing 2B4, e.g., monocytes, basophils, γδ T cells, etc. As CD48 was also shown to function as an activating receptor, 2B4/CD48 binding in the settings of NK-to-NK or NK-to-non-NK cell interactions may generate bidirectional signals. To address this question, we examined the consequence of CD48 or 2B4 ligation using two experimental settings: one with target (syngeneic EL4 and allogeneic P815) cells, ectopically expressing surface 2B4 or CD48, and the other with direct cross-linking with plate-bound mAb. Here, we report that ligation of CD48 with 2B4+ EL4 or 2B4+ P815 targets, in the absence of other receptor engagement, did not alter NK cell cytotoxicity or proliferation significantly. Similarly, cross-linking of NK cells with plate-bound anti-CD48 mAb in the absence or presence of a suboptimal dose of IL-2 did not modulate NK proliferation, cytotoxicity, or cytokine production. Nonetheless, 2B4 cross-linking promoted NK cell proliferation and effector functions consistently in both settings. Therefore, our results demonstrate unequivocally that CD48 on surrounding NK or non-NK cells serves primarily as a ligand to stimulate 2B4 on the adjacent NK cells in mice.
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