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Human B cell development. II. Subpopulations in the human fetus
Journal of Immunology (Baltimore, Md. : 1950)
|March 1, 1985
Summary
Fetal B cell development reveals distinct phenotypes in different tissues. Early B cells in fetal liver and bone marrow differ from later peripheral B cells expressing T cell markers.
Area of Science:
- Immunology
- Developmental Biology
- Hematology
Background:
- B cell populations exhibit distinct phenotypes during human fetal development.
- Early B cells in fetal liver and bone marrow express specific markers (IgM, CD20, CD24) but lack others (IgD, CD22, CD21, CD24).
- Peripheral B cells in the fetus are heterogeneous, with varying marker expression.
Purpose of the Study:
- To characterize the distinct phenotypes of B cell populations during human fetal development.
- To identify the emergence and distribution of specific B cell subsets in fetal tissues.
- To explore the potential relationship between fetal B cell populations and certain lymphoid malignancies.
Main Methods:
- Immunophenotyping of fetal B cells using a panel of monoclonal antibodies.
- Analysis of B cell marker expression (IgM, IgD, CD20, CD22, CD21, CD24, CD5, Tü-33) in fetal liver, bone marrow, lymph nodes, and spleen.
- Correlation of B cell phenotypes with gestational age and tissue site.
Main Results:
- Pre-B and B lymphocytes in fetal liver/bone marrow express IgM, CD20, and CD24.
- Peripheral B cells in lymph nodes and spleen (16-21 weeks) are IgM+, IgD+, CD22+, CD21+, CD24+ but lack CD5 and Tü-33.
- Fetal lymph nodes develop nodules (from 17 weeks) with B cells expressing IgM, IgD, CD20, CD22, CD21, CD24, and CD5; a subset also expresses Tü-33.
- Similar CD5+ B cells appear later in the spleen (around 22 weeks) and can be found in peritoneal/pleural cavities.
- These CD5+, IgM+ B cells are proposed as the human equivalent of murine Ly-1+ B cells and potential counterparts of B chronic lymphoid leukemia and centrocytic lymphoma.
Conclusions:
- Distinct B cell subsets with unique phenotypes emerge sequentially during human fetal development.
- The CD5+, IgM+ B cell population identified in fetal tissues may represent a distinct lineage with implications for understanding lymphoid malignancies.
- This study provides insights into the ontogeny of B cell populations and their potential role in disease.