No role of interleukin-4 in CD23/IgE-mediated enhancement of the murine antibody response in vivo.
Antigen-specific IgE up-regulates the specific IgM, IgG1, IgG2a and IgE response in vivo when given to mice together with antigen. The enhancement is mediated by the low-affinity receptor for IgE, Fc epsilon RII or CD23, as demonstrated both in CD23-deficient mice and by blocking CD23 with anti-CD23 monoclonal antibodies. A possible mechanism behind the regulatory effects of CD23 is that the IgE/CD23/antigen complex is endocytosed by B cells, leading to increased antigen processing and presentation on major histocompatibility complex (MHC) class II molecules to T helper cells. In the present study we have found that the expression of CD23 is reduced fivefold on splenic B cells in mice genetically deficient for IL-4. When IL-4-deficient mice and normal littermates were immunized with 2,4,6-trinitrophenyl (TNP)-specific IgE followed by bovine serum albumin (BSA)-TNP or with BSA-TNP alone, the BSA-specific IgG1 and IgG2a responses were equally well augmented by IgE in all mice. In addition, a low but significant IgE response was seen even in the IL-4-deficient mice. Thus, enhancement of the antibody response through IgE and CD23 occur in the absence of IL-4 and is not dependent on CD23 up-regulation.
Hjulström
S
S
Department of Pathology, Uppsala University Hospital, Sweden.
Landin
A
A
Jansson
L
L
Holmdahl
R
R
Heyman
B
B
D000818:Animals; D000917:Antibody Formation; D000918:Antibody Specificity; D016175:B-Lymphocyte Subsets / Q000276:immunology; D001483:Base Sequence; D003433:Crosses, Genetic; D005260:Female; D005786:Gene Expression Regulation; D007073:Immunoglobulin E / Q000276:immunology*; D015847:Interleukin-4 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D046911:Macromolecular Substances; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017455:Receptors, IgE / Q000276:immunology*; D013154:Spleen / Q000473:pathology
D046911:Macromolecular Substances; D017455:Receptors, IgE; D015847:Interleukin-4; D007073:Immunoglobulin E