The close relation between rat mast cells and rat basophilic leukemia (RBL) cells with regard to the presence of receptors for IgE and Fc gamma led us to generate monoclonal antibodies directed against cell surface antigens. Hybridomas were obtained by the fusion of NS1 mouse myeloma cells with murine spleen and lymph node cells. The culture supernatants were assayed by two ELISA techniques: a) for the production of mouse immunoglobulin in general and b) for antibodies directed against surface antigens of RBL cells. For this purpose RBL cells were attached to polyvinyl chloride microtitre plates. Eight hybrids produced antibodies directed against surface antigens on RBL cells. Hybrids were cloned and characterized with regard to their isotype and light chains. All eight clones secreted IgM with K light chains. Immunofluorescence studies performed with RBL cells revealed that all eight antibodies were able to show a specific fluorescence. Furthermore, four of these eight antibodies also showed a specific fluorescence with purified rat mast cells. These four antibodies were analyzed as to their ability of interacting with the IgE-receptor on RBL cells and purified rat mast cells. They reduced the binding rate of radiolabelled rat IgE to RBL and rat mast cells. A mutual inhibition of the passive cutaneous anaphylaxis (PCA) reaction in the rat by either mixing mouse reaginic serum directed against 2,4-dinitrophenol bovine serum albumin (DNP-BSA) or by mixing monoclonal mouse anti-DNP IgE with the monoclonal mouse anti-cell surface (rat basophilic leukemia, rat mast cell) IgM was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Generation of cell-derived factors suppressing IgE synthesis of Nippostrongylus brasiliensis-infected mice in vitro.

Modulation of de novo IgE synthesis in vitro was studied using the parasitic infection of mice with the nematode Nippostrongylus brasiliensis. Cell-derived factors were generated by stimulation of splenic and mesenteric lymph node cells of BALB/c mice with monoclonal IgE in vitro. High molecular weight (greater than 50,000) and low molecular weight (less than 50,000) culture supernatants were prepared. De novo IgE synthesis of BALB/c lymphocytes--obtained from N. brasiliensis-reinfected mice that secreted pronounced quantities of IgE in vitro--was markedly reduced by the addition of high molecular weight supernatants. A dose-dependent suppression of IgE synthesis was obtained, whereas IgG synthesis, viability, and cell proliferation were not inhibited. After fractionation of low molecular weight supernatants with IgE-Sepharose the glycine/HCl eluate fractions markedly inhibited the in vitro IgE synthesis. Low molecular weight factors which suppressed IgE synthesis without modulating IgG production were obtained from IgE high responder B6D2F1 normal mouse cells. Thus, our results demonstrate the generation of IgE-specific suppressor factors in vitro upon stimulation with IgE. The suppression of IgE synthesis by eluate fractions of low molecular weight supernatants absorbed with IgE-Sepharose suggest a potential role for IgE binding factors on de novo IgE synthesis in vitro.

Animals↗

PubMed1986

[Modulation of IgE antibody synthesis by immunoglobulin-binding factors].

The presence of immunoglobulin-binding factors with immunomodulatory activity was described. These factors were shown in vivo and in vitro in experimental animals as well as in man. The IgG, IgA and IgE antibody response is affected in an isotype-specific manner. Binding factors are derived from Fc receptor-expressing T- and B-cells stimulated either by incubation with the respective immunoglobulin and/or antigen which leads to enhanced Fc receptor expression as well as secretion of the corresponding binding factor. In addition to the inducing antibody the biological activity appears to be defined by the environmental conditions. Binding factors not only exert a direct modulation of plasma cells but affect isotype-specific lymphocytes with helper or suppressor functions.

Animals↗

PubMed1986