ABSTRACT
In murine in vivo systems, Ags administered in physiologic solutions together with specific IgE induce a significantly higher Ab response than Ags administered alone. In vitro, IgE in complex with Ag enhances B cell-mediated presentation of the Ag to T cells. Both phenomena require an intact low affinity receptor for IgE (Fc epsilon RII/CD23), suggesting that the effect on in vivo Ab responses is caused by increased Ag presentation. We here show that mice carrying the MHC class II Ab molecule (e.g., C57BL/6 and 129/Sv) do not produce Abs to BSA when immunized with BSA-2,4,6-trinitrophenyl (TNP) in complex with monoclonal IgE anti-TNP. In contrast, strains of all other MHC haplotypes tested (H-2d, H-2k, H-2p, H-2q, and H-2s) respond vigorously to IgE/BSA-TNP complexes, with Ab responses several hundred-fold higher than the responses in H-2b mice. C57BL/6 mice were unable to produce a carrier-specific response also after immunization with IgE/OVA-TNP, IgE/diphtheria toxoid-TNP, or IgE/tetanus toxoid-TNP. Although the low responsiveness mapped to the Ab region, responsiveness was not restored in C57BL/6 mice carrying transgenic Ak, suggesting that a nonclassical A-region-encoded gene product is involved. Most importantly, our data call attention to the fact that the C57BL/6 and 129 mouse strains, which are widely used for producing transgenic animals, have defective immune responses.
Subject(s)
Antibody Formation/genetics , H-2 Antigens/genetics , Animals , Antigens/administration & dosage , Crosses, Genetic , Dose-Response Relationship, Immunologic , Drug Combinations , Epitopes/administration & dosage , Female , Freund's Adjuvant/administration & dosage , Genetic Linkage/immunology , Histocompatibility Antigens Class II/biosynthesis , Histocompatibility Antigens Class II/genetics , Immunoglobulin E/administration & dosage , Immunoglobulin G/biosynthesis , Immunoglobulin G/genetics , Injections, Intravenous , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred CBA , Mice, Inbred DBA , Mice, Inbred Strains , Mice, Transgenic , Phenotype , Serum Albumin, Bovine/administration & dosage , Trinitrobenzenes/administration & dosageABSTRACT
The activity of purified 12 alpha-hydroxylase from rabbit liver microsomes was modulated by including protein fractions from rabbit liver microsomes and cytosol into the system. The microsomal protein fraction stimulated 12 alpha-hydroxylation two times. The cytosolic fraction inhibited the reaction markedly. The microsomal 12 alpha-hydroxylase stimulatory activity was labile and the cytosolic 12 alpha-hydroxylase inhibitory activity was stable to mild heat treatment. Addition of ATP and MgCl2 or NaF had no effect on the activities of the two protein fractions. The activity of the microsomal stimulatory fraction decreased upon storage but could be reactivated by addition of reduced glutathione to the system.
