Establishment of hybridomas secreting monoclonal antibodies against C epsilon 2 and C epsilon 4 domains of human IgE

Improvement in the antibody productivity of human-human hybridomas by transfection with Tac gene

The presence of a highly purified recombinant interleukin-2 (rIL-2) increased the production of immunoglobulin (IgM or IgG) by human-human hybridomas to 1.5-2.0 times the production by untreated cells. However, these cells did not react with anti-Tac (IL-2 receptor alpha) antibody. To enhance the response of the hybridoma cells to rIL-2, Tac gene was introduced by co-transfection with Tac gene expression plasmid pTB459 and G418 resistant gene expression plasmid pRSVneo. Tac cDNA transfected hybridoma (HBW-4.16.459-6-126) was induced to produce 6 times as much IgG by rIL-2 as was the control. This antibody production promoting phenomenon mediated by rIL-2 was depressed by anti-Tac antibody.

Generation and characterization of murine monoclonal antibodies specific for bovine immunoglobulin E

Monoclonal antibodies were produced against serum-derived bovine immunoglobulin E (IgE). Culture supernatants of hybridomas were initially screened by enzyme-linked immunosorbent assay (ELISA). Supernatant-derived antibodies were concentrated and further characterized using ELISA, reverse cutaneous anaphylaxis, immunohistochemical staining, and immunoblotting of IgE-containing samples separated by SDS-polyacrylamide gel electrophoresis (PAGE). Eight monoclonal antibodies showed specificity for bovine epsilon immunoglobulin heavy chain. Two antibodies (E2 and E32) reacted in immunoblots of SDS-PAGE of serum IgE under reducing conditions. Additionally, E2, E5, and E32 detected epsilon chain in serum separated by SDS-PAGE and then renatured. Antigen-specific IgE was detected in Western blots by E5 and E32. Immunoperoxidase staining of IgE-containing cells in mesenteric lymph node sections was detected with E5, E21 and E32. All eight antibodies produced positive reverse cutaneous anaphylaxis reactions in calf skin. All functioned well in ELISA as a plate-sensitizing reagent for quantitation of total IgE; E5 and E32 worked well as a primary antibody in antigen-specific IgE assays. These antibodies will be useful in research applications and in diagnostic assays.

In vitro synthesis of IgE antibody by human tonsil mononuclear cells. Preliminary report

Using anti-human IgE monoclonal antibody E235I63, an IgE antibody to mite extract response by peripheral blood lymphocytes (PBL) and tonsillar lymphoid cells from 3 atopic patients suffering nasal allergy and 2 normal individuals was detected by a sensitive radioimmunoassay of culture supernatants. Although the spontaneous IgE antibody response was characteristic of atopic PBL, PBL of normal controls did not produce anti-mite IgE antibody spontaneously. IgE antibody to mite extracts were detected in supernatants of all tonsillar cells cultured with mite antigen or PWM, but PBL from only atopic donors could produce IgE antibody in the same conditions.

Purification and characterization of a recombinant human IgE Fc epsilon fragment lacking the C4 domain

Complementary DNA of human IgE Fc epsilon fragment (residues 226-480) lacking the C epsilon 4 domain was expressed in Escherichia coli and the product was purified by immunoaffinity chromatography on a monoclonal antibody (E12 0.02)-Affi-Gel 10 column. About 1.8 mg of an apparent dimer and 5.9 mg of a monomer were obtained from 65 g E. coli cells with 9.3% recovery. The purified products were found to lack more than half of the COOH-terminal portion of the C epsilon 3 domain. The apparent dimer showed high immunological specific activity (3.6 x 10(6) U/mg protein) comparable to that of natural human IgE when measured by commercial human IgE determination kits.

Thermally induced disulfide bond exchanges in human IgE

The thermally induced changes in human IgE was investigated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When the IgE (1 mg/ml) was heated at 56 degrees C for several hours in the absence of sodium dodecyl sulfate, it gave aggregated forms that could be reduced completely to heavy and light chains with dithiothreitol. On the other hand, in the presence of sodium dodecyl sulfate (0.1%), the IgE was changed by heating to five components with small mol. wts dependent on temperature and pH. This phenomenon was observed also in mouse monoclonal IgG1, but the degree of change was considerably lower than that of human IgE. The five components obtained from the heat-treated IgE (LHHL) were identified as LHHL, HL, H, LL and L. These results show that the thermally induced changes in human IgE are dependent on the exchange of its intra- and inter-disulfide bonds.

Studies of the IgE binding sites to rat mast cell receptor with proteolytic fragments and with a monoclonal antibody directed against epsilon heavy chain: evidence that the combining sites are located in the C epsilon 3 domain

The binding sites of rat IgE to mast cell receptor were investigated by the use of proteolytic fragments and a monoclonal antibody to epsilon chain (MARE-1). Three main fragments were characterized by short-time papain digestion of IgE: F(ab')2-E, a fragment related to the C, 4 domain, and an asymmetric fragment corresponding probably to an IgE molecule with one proteolyzed C, 3 domain. Neither F(ab')2-E nor C, 4 could interfere with the binding of IgE to rat mast cells. These two fragments did not show significant polymerization upon heating at 56 degrees C, while large amounts of polymers were produced from whole IgE, MARE-1 monoclonal antibody was found to react neither with F(ab')2 nor with C, 4, thereby suggesting its interaction with the C, 3 domain. MARE-1 was found to inhibit partially (about 55%) the binding of IgE to its receptor. Taken together the results indicate that the binding sites of IgE to rat mast cell receptor are located within the C, 3 domain. In addition, isolation of the C, 4 domain will be useful to evaluate its participation in the affinity of IgE to receptors of other cells such as lymphocytes or macrophages.

Purification and characterization of IgE produced by human myeloma cell line, U266

Human IgE was isolated for the first time from the supernatant of the culture fluid of a human myeloma cell line, U266. The purification procedure consisted of salting out from the supernatant with ammonium sulfate, affinity chromatography on a lysine-Sepharose 4B column, ion exchange chromatography on a DEAE-Sephacel column, gel filtration and recycling chromatography on a Sephacryl S-300 column and removal of bovine proteins on an anti-bovine serum rabbit IgG-Sepharose 4B column. One hundred and twenty eight milligrams of IgE was recovered from 461 of culture fluid. The purification was extremely simplified by the introduction of immunoaffinity chromatography using the monoclonal antibody prepared by immunizing a mouse with an IgE preparation obtained by the above method: about 3.3 mg was recovered from 960 ml of culture fluid. The purified preparation was homogeneous as judged by the double-immunodiffusion test and end group analysis. The amino acid and carbohydrate compositions of the preparation coincided with those reported on other preparations obtained from the sera of myeloma patients. Our preparation, however, showed two bands with apparent mol. wts of 240,000 and 230,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. When it was reduced with dithiothreitol and analyzed by electrophoresis, it gave two heavy chains and one light chain with apparent mol. wts of 80,000 and 76,000, and 28,000, respectively. On the other hand, the IgE molecule that was synthesized and secreted into the medium in the presence of tunicamycin (0.5 microgram/ml) gave only one heavy chain and one light chain with apparent mol. wts of 62,000 and 28,000, respectively. These results demonstrated that the two IgE molecular species contained in our preparation differed from each other in the carbohydrate moiety in their heavy chains.