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Updated: Aug 11, 2026
Isolation and Activation of Murine Lymphocytes
Published on: October 30, 2016
Phagocytosis of immunobeads by CD8 positive lymphocytes during magnetic cell sorting
Olaf Burkhardt1, Hans-Joachim Merker
1Department of Clinical Pharmacology and Toxicology, Benjamin Franklin Medial Center, Freie Universitat Berlin, Germany.
Insights
Human CD8 positive lymphocytes exhibit receptor-mediated phagocytosis of immunobeads at room temperature. Maintaining a low temperature (4°C) is crucial for accurate cell separation and analysis.
Area of Science:
- Immunology
- Cell Biology
Background:
- Human blood lymphocytes are crucial for immune responses.
- CD8 positive lymphocytes, or cytotoxic T lymphocytes, play a key role in cell-mediated immunity.
- Accurate separation of lymphocyte subsets is vital for immunological research.
Purpose of the Study:
- To investigate the interaction between immunobeads and human CD8 positive lymphocytes.
- To determine if bead adherence and incorporation indicate specific cellular processes.
- To provide recommendations for optimizing lymphocyte separation techniques.
Main Methods:
- Isolation of human blood lymphocytes using Ficoll gradients.
- Separation of CD8 positive lymphocyte fraction via the Immunobead Technique.
- Electron microscopic examination of lymphocytes after incubation with immunobeads at room temperature.
Main Results:
- Adhering immunobeads were observed on all CD8 positive lymphocytes, but not in the negative fraction.
- Approximately 2% of CD8 positive lymphocytes showed bead incorporation, indicating phagocytosis.
- Phagocytosis-like processes, including pseudopod formation, were evident around adhering beads.
- Bead incorporation was specific to the CD8 positive fraction, suggesting receptor-mediated phagocytosis.
Conclusions:
- CD8 positive lymphocytes are capable of specific, receptor-mediated phagocytosis of immunobeads at room temperature.
- This phagocytic activity can influence cell separation and analysis, particularly with magnetic separation techniques.
- Maintaining a low experimental temperature, such as 4°C, is recommended to prevent bead incorporation and ensure accurate results.
Abstract:
Lymphocytes of human blood were isolated by Ficoll gradients and separated into a CD8 positive fraction using the "Immunobead Technique". Electron microscopic examination approximately 45 min after mixing with the beads at room temperature revealed adhering beads in all cells of the CD8 positive fraction, whereas the negative fraction did not exhibit any adhering beads. About 2% of the lymphocytes of the positive fraction additionally showed bead incorporations. These cells exhibited a characteristic lymphocytic morphology and must be considered T lymphocytes. Formation of processes and ridges in the vicinity of the adhering beads points to a phagocytosis-like process. Since incorporations of beads can be demonstrated only in the CD8 positive fraction, this type of phagocytosis must be a specific; i. e. receptor-mediated phagocytotic process. The capability to perform phagocytosis by CD8 positive lymphocytes at room temperature should be considered during separation and when evaluating the behaviour of cells after magnetic separation, e. g. when attempting to remove the beads again. An exact experimental temperature (4 degrees C) should therefore be maintained.
