Human antibodies and hybridomas最新文献

Human monoclonal antibody (hMAb) AE6F4 has been shown to be potentially useful for immunocytological detection of lung cancer cells in sputum. By recombinant DNA technology, IgM type hMAb AE6F4 was switched to lgG. The IgG mimic recombinant AE6F4 antibody expression plasmid was assembled using the antibody heavy chain gene, which ligated the gene encoding VH and CH1(mu) domains of hMAb AE6F4 heavy chain to the gene encoding CH2(gamma 1) and CH3(gamma 1) domains of human IgG heavy chain, and the antibody light chain gene of hMAb AE6F4. The recombinant antibody expressed by baby hamster kidney (BHK)-21 cells showed molecular size equivalence to IgG, and consisted of human mu-gamma hybrid heavy and kappa light chains. The immunological specificity of the recombinant antibody was the same as that of hMAb AE6F4 by immunoblotting analysis to the 14-3-3 protein, the putative antigen of hMAb AE6F4, and by immunohistochemical and immunocytological analyses using tissue sections and sputa of lung cancer patients. The transfected BHK-21 cells produced the recombinant antibody persistently and the productivity was greater than 20 times that by human-human hybridoma producing hMAb AE6F4.

Primary antiphospholipid syndrome (PAPS) is a recently recognized clinical entity encompassing the combination of thromboembolic phenomena, thrombocytopenia and recurrent abortions in the presence of antiphospholipid antibodies. We present a patient with PAPS accompanied by renal involvement, manifested as membranous nephropathy, as proven by a renal biopsy. To investigate further the possible association between PAPS and the renal lesions we attempted to induce similar renal manifestations by transferring peripheral blood lymphocytes (PBL) from this patient to severe combined immunodeficiency (SCID) mice. The mice transfused with PBL from the affected patient exemplified antiphospholipid antibodies (aPL) following which a renal lesion consistent with the human membranous nephropathy lesion was precipitated. This study substantiates the role of aPL as possible inducers of renal damage.

We describe in this paper the rapid and cheap purification of human immunoglobulin M from hybridoma supernatant of mass culture. The method consists of two steps: 1. concentration of supernatant by ultrafiltration and 2. dialysis against distilled water, pH 6.4. To produce the supernatant, the hybridomas are grown in RPMI media with fetal calf serum (10% FCS) in 250 ml flasks under normal tissue culture conditions. More than 14 mg IgM can be nearly selectively purified within 6 h from 5 l of antibody containing hybridoma supernatant. Most of the IgM molecules stay in a penta- and monomeric form and are positive in physiological and immunohistochemical studies.

Interleukin-6 (IL-6) inhibitors are good potential therapeutic agents in human patients, and anti-IL-6 antibodies are among the best candidates. Here, we have successfully humanized mouse monoclonal antibody SK2, which specifically binds to IL-6 and strongly inhibits IL-6 functions. Since this antibody possesses N-linked carbohydrates on Asn-30 of VH region, which seems to be very close to an antigen-binding site, influence of these carbohydrates on antigen-binding was investigated. A biosensor study showed that the mouse SK2 Fab and its deglycosylated fragments had almost equal Kd (Kon/Koff), 26.8 nM (1.05 x 10(6)/2.81 x 10(-2)) and 24.7 nM (1.28 x 10(6)/3.15 x 10(-2)), respectively. Furthermore, a mutant chimeric SK2 antibody, in which the N-glycosylation site was removed from the VH region, showed a Kd of 11 nM, almost similar to that of the original chimeric SK2 antibody, determined by Scatchard analysis with 125I-IL-6. These data indicate the carbohydrates of mouse SK2 VH region do not significantly influence antigen-binding activity. In the next step, two versions of each humanized SK2 VL and VH regions were carefully designed based on the amino acid sequences of human REI and DAW, respectively. Only one alteration, Tyr to Phe, was made at position 71 in the two light chains, according to the canonical residue for LI. A N-glycosylation site was introduced on the two heavy chains, by changing Ser to Asn at position 30. All four combinations of humanized light and heavy chains could bind to IL-6 as well as the chimeric SK2 antibody. The light chain first version, however, could not efficiently inhibit IL-6 binding to its receptor, indicating the importance of the LI loop conformation for the inhibitory activity of SK2 antibody. In contrast, both versions of the heavy chains were comparable, in yielding good humanized SK2 antibodies, suggesting that the glycosylation of the SK2 VH region has no influence in recreating a functional antigen-binding site in this humanization.

Amino acid sequence homology between tetanus toxoid, a common vaccine and melittin, a bee venom allergen provided us with two antigen models for studying the production of cross reactive antibodies after immunisation. Analysis of the serum of an atopic patient recently boosted with tetanus toxoid revealed the presence of anti-melittin and anti-tetanus antibodies. From this donor a phage display Fab library was constructed five days after vaccination. Screening of this library either with melittin alone or with tetanus toxoid followed by melittin allowed the isolation of Fab fragments specific to melittin but also Fab fragments which cross react with melittin and tetanus toxoid. Amino acid analysis revealed diversity in the heavy and the light Ig chains of the melittin specific and of the cross reactive clones. Interestingly we found that the light chain recognised melittin whereas the heavy chain preferentially bound to tetanus toxoid suggesting that cross reactivity may be due to the different binding specificities of the individual Ig chains.