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Isolation of Precursor B-cell Subsets from Umbilical Cord Blood
Published on: April 16, 2013
BY55 monoclonal antibody delineates within human cord blood and bone marrow lymphocytes distinct cell subsets
A Bensussan1, E Gluckman, S el Marsafy
1Institut National de la Santé et de la Recherche Médicale Unité 93, Hôpital Saint-Louis, Paris, France.
Insights
The BY55 antibody identifies distinct cytotoxic lymphocyte populations in bone marrow and cord blood. Cord blood CD3-BY55+ cells are the primary natural killer cells, lacking cytotoxic T lymphocyte activity.
Area of Science:
- Immunology
- Hematology
- Cell Biology
Background:
- The BY55 monoclonal antibody targets an 80-kDa protein on human peripheral blood cytotoxic lymphocytes.
- Cytotoxic lymphocytes, including natural killer (NK) cells (CD3-) and cytotoxic T lymphocytes (CTLs) (CD3+CD8+), are crucial for immune responses.
- Bone marrow and cord blood are key sources of hematopoietic stem cells for transplantation.
Purpose of the Study:
- To investigate the presence and phenotype of BY55+ cytotoxic lymphocytes in adult bone marrow and newborn cord blood.
- To characterize the functional activity of these BY55+ cell subsets in both tissues.
Main Methods:
- Flow cytometry using BY55 monoclonal antibody to identify cell surface protein expression.
- Immunophenotyping to determine CD3, CD8, and NK cell markers.
- Functional assays to assess cytotoxic T lymphocyte and natural killer cell activity.
Main Results:
- In adult bone marrow, 5-10% of lymphocytes were BY55+, predominantly CD3+CD8+ cytotoxic T lymphocytes.
- In newborn cord blood, 20-35% of lymphocytes were BY55+, exclusively within the CD3- subset.
- Cord blood exhibited no cytotoxic T lymphocyte activity, while the CD3-BY55+ subset contained all natural killer activity.
Conclusions:
- The BY55 marker distinguishes different cytotoxic lymphocyte populations in adult bone marrow and cord blood.
- The CD3-BY55+ cell subset in cord blood represents the primary natural killer cell population with significant cytotoxic potential.
- These findings have implications for understanding immune cell composition in stem cell sources for transplantation.
Abstract:
We had previously reported, using BY55 monoclonal antibody, a cell surface 80-kDa protein restricted to human functional peripheral blood cytotoxic lymphocytes with either natural killer CD3- or cytotoxic T lymphocyte CD3+CD8+ phenotype. In the present report, we studied the cytotoxic lymphocytes in adult bone marrow and newborn cord blood as these organs are commonly used as sources of hematological stem cells for allogeneic transplantation. Our results showed that BY55 mAb labeled only 5-10% of the bone marrow lymphocytes, which included a major proportion of CD3+ CD8+ cytotoxic T lymphocytes. Interestingly, within cord blood cells, BY55+ lymphocytes represented 20-35% of the lymphocytes corresponding exclusively to a CD3- cell subset. Furthermore, we detected in cord blood no cytotoxic T lymphocyte activity but we demonstrated that the CD3-BY55+ cell subset contained the whole natural killer activity.
