Abstract
IgE Abs, passively administered together with their specific Ag, can enhance the production of Abs recognizing this Ag by >100-fold. IgE-mediated feedback enhancement requires the low affinity receptor for IgE, CD23. One possible mechanism is that B cells take up IgE-Ag via CD23 and efficiently present Ag to Th cells, resulting in better Ab responses. To test whether IgE Abs have an effect on Th cells in vivo, mice were adoptively transferred with CD4+ T cells expressing a transgenic OVA-specific TCR, before immunization with IgE anti-TNP (2,4,6-trinitrophenyl) plus OVA-TNP or with OVA-TNP alone. IgE induced a 6- to 21-fold increase in the number of OVA-specific T cells. These cells acquired an activated phenotype and were visible in splenic T cell zones. The T cell response peaked 3 days after immunization and preceded the OVA-specific Ab response by a few days. Transfer of CD23+ B cells to CD23-deficient mice rescued their ability to respond to IgE-Ag. Interestingly, in this situation also CD23-negative B cells produce enhanced levels of OVA-specific Abs. The data are compatible with the Ag presentation model and suggest that B cells can take up Ag via "unspecific" receptors and activate naive T cells in vivo.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adjuvants, Immunologic / administration & dosage*
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Adjuvants, Immunologic / physiology*
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Animals
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Antibody Formation* / genetics
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Antigen Presentation / genetics
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Antigen-Antibody Complex / administration & dosage
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Antigen-Antibody Complex / physiology
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B-Lymphocyte Subsets / immunology*
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B-Lymphocyte Subsets / metabolism
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B-Lymphocyte Subsets / transplantation
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CD4-Positive T-Lymphocytes / immunology
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CD4-Positive T-Lymphocytes / metabolism
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CD4-Positive T-Lymphocytes / transplantation
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Epitopes, T-Lymphocyte / immunology*
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Epitopes, T-Lymphocyte / metabolism
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Haptens / administration & dosage
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Haptens / immunology
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Immunoglobulin E / administration & dosage*
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Immunoglobulin E / metabolism
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Immunoglobulin E / physiology*
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Lymphocyte Activation / genetics
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Lymphocyte Activation / immunology
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Mice
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Mice, Congenic
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Mice, Inbred BALB C
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Mice, Transgenic
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Ovalbumin / administration & dosage
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Ovalbumin / immunology
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Receptors, IgE / biosynthesis*
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Receptors, IgE / deficiency
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Receptors, IgE / genetics
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T-Lymphocytes / immunology*
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T-Lymphocytes / metabolism
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Trinitrobenzenes / administration & dosage
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Trinitrobenzenes / immunology
Substances
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Adjuvants, Immunologic
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Antigen-Antibody Complex
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Epitopes, T-Lymphocyte
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Haptens
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Receptors, IgE
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Trinitrobenzenes
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trinitrophenyl-ovalbumin
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Immunoglobulin E
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Ovalbumin