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Immunoreactive lactoferrin in resting, activated, and neoplastic lymphocytes
T W Butler1, C E Grossi, A Canessa
1Department of Medicine, University of Alabama, Birmingham 35294.
Insights
Lactoferrin (Lf) is mainly found on the surface of B-lymphocytes, particularly in chronic lymphocytic leukemia. Its presence on lymphocytes may increase during B-cell maturation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Lactoferrin (Lf) is an iron-binding protein with immunomodulatory functions.
- Its presence and role on lymphocyte surfaces require further investigation.
Purpose of the Study:
- To investigate the expression and localization of lactoferrin (Lf) on human lymphocytes.
- To determine if Lf expression varies across different lymphocyte subsets and conditions.
Main Methods:
- Immunofluorescence and flow cytometry were used to detect surface and intracellular Lf.
- Analysis included various lymphocyte populations, including B-cells, T-cells, and specific leukemia/lymphoma cell lines.
Main Results:
- Surface Lf was predominantly detected on B-cell-enriched preparations.
- B-cell chronic lymphocytic leukemia (B-CLL) lymphocytes showed the highest surface Lf positivity.
- Few T-lymphocytes expressed Lf, and its expression was stable over time and unaffected by exogenous Lf.
- Surface Lf positivity was independent of cell cycle and most other surface antigens.
Conclusions:
- Lactoferrin is primarily associated with the surface of B-lymphocytes.
- Increased Lf expression may occur during specific stages of B-cell maturation.
- Lf may play a role in B-lymphocyte function and differentiation.
Abstract:
Lactoferrin (Lf) in lymphocytes was assessed with immunofluorescence/flow cytometric technique. Surface Lf was detected primarily among B-cell-enriched preparations. Tonsillar B-cells of different densities expressed surface Lf similarly. Very small percentages of CALLA+ ALL, HCL, or EBV-transformed B-cells expressed surface Lf, whereas B-CLL lymphocytes had the highest percentages of surface Lf positivity. Few resting, cultured, or neoplastic T-lymphocytes expressed Lf. The pattern of immunofluorescence and analyses of surface and total cellular immunoreactive Lf indicated that Lf is associated primarily with the lymphocyte surface. The percentage and/or intensity of surface Lf-specific fluorescence were not significantly altered in B- or T-cells by incubation with physiologic concentrations of differric Lf, and the percentages of Lf-positive cells detected in respective subjects remained stable over time. Surface Lf positivity was unrelated to the expression of other surface antigens (except those marking B- or T-cell lineage) or cell cycle. Expression and/or binding of Lf in B-lymphocytes may become increased during certain stages of cell maturation.