A subpopulation of normal human peripheral B lymphcytes that bind IgE

Area of Science:

• Immunology
• Cell Biology

Background:

• Immunoglobulin E (IgE) plays a crucial role in allergic reactions and defense against parasites.
• Identifying cells that bind IgE is essential for understanding immune responses.

Purpose of the Study:

• To investigate the presence and characteristics of IgE-binding lymphocytes in normal human peripheral blood.

Main Methods:

• Rosette formation assay using IgE-coated red blood cells (Eo'-IgE) to detect IgE-binding lymphocytes.
• Analysis of lymphocyte surface markers, including spontaneous sheep erythrocyte rosettes (E), surface immunoglobulin (SIg), and IgG-coated ox red cell rosettes (EoA).
• Inhibition studies using IgE fragments and trypsin treatment to characterize the IgE-binding receptor.

Main Results:

• Approximately 4.3% of normal human lymphocytes formed Eo'-IgE rosettes, indicating IgE binding.
• The majority of IgE-binding lymphocytes were SIg-positive, suggesting a B-cell phenotype.
• IgE binding was inhibited by IgE myeloma proteins and Fc fragments, but not by Fab fragments or other immunoglobulin classes.
• Over 90% of IgE-binding lymphocytes lacked Fc receptors for IgG.
• Trypsin treatment abolished IgE rosette formation, indicating trypsin-sensitive receptors.

Conclusions:

• A subpopulation of normal human peripheral lymphocytes, likely B-cells, possesses trypsin-sensitive receptors specific for the Fc fragment of IgE.
• These IgE-binding lymphocytes share surface marker characteristics with cultured lymphoblastoid cells known to bind IgE.