Cloning and expression of cDNAs encoding the variable domains of the antibreast carcinoma antibody Mc5

In vivo clearing of idiotypic antibodies with antiidiotypic antibodies and their derivatives

At immunolocalization of experimental tumors, idiotypic monoclonal antibodies, such as TS1 against cytokeratin 8, can be used to carry and deposit in vivo terapeutics in the tumor. These carriers also remain in the circulation and may cause negative side-effects in other tissues. In this report, several derivatives of the antiidiotypic antibody alphaTS1 were produced and tested for their clearing capacity of the idiotypic carrier antibody TS1. Intact monoclonal alphaTS1, scFv of a alphaTS1 and alphaTS1 Fab'2 and fragments were produced by recombinant technology or by cleavage with Ficin. The scFv was tailored by use of the variable domain genes of the light and heavy chain from the hybridoma clone in combination with a (Gly4Ser)3-linker, followed by expression in E. coli. When tested for clearing capacity, the intact divalent antiidiotypic IgG was found to be the most efficient. The divalent and the monovalent Fab fragment also demonstrated significant clearing, but lower than the intact antiidiotypic IgG. The alphaTS1 scFv antibody when injected separately was not found to clear the idiotype, but could do so when preincubated with the idiotype. Rapid excretion and in vivo instability of this low molecular weight antibody fragment may be the major reasons. Similar results were obtained when the system was reversed and the 131I-labeled antiidiotype IgG was cleared with the idiotype fragment. It is concluded that both intact antiidiotypic IgG, and Fab'2 fragments are able to clear the idiotypic antibodies. The experimental data support the conclusion that the Fc parts from both the idiotype and the antiidiotype may contribute to this elimination.

Identical alpha-chain T-cell receptor transcripts are present on T cells infiltrating coronary arteries of human cardiac allografts with chronic rejection

Chronic cardiac allograft rejection is characterized by graft arteriopathy and is a major obstacle of graft survival. We investigated T-cell receptor (TCR) alpha-chain transcripts of T cells infiltrating human epicardial coronary arteries from cardiac allografts with chronic rejection. The non-palindromic adaptor-polymerase chain reaction (NPA-PCR) was used to specifically amplify TCR alpha-chain transcripts from five explanted cardiac allografts with chronic rejection. The amplified products were cloned and sequenced to obtain the entire ValphaJalpha region. Immuno-histochemistry was used to identify the mononuclear cell infiltrates in the coronary arteries. All the five coronary artery specimens exhibited large populations of infiltrating mononuclear cells, which were primarily comprised of T cells and macrophages. In three specimens, high proportions ( approximately 80%) of identical alpha-chain TCR transcripts were detected. In peripheral blood mononuclear cells from a healthy individual, alpha-chain TCR transcripts were unique when compared to each other. Endomyocardial biopsies collected from one patient six months before the allograft was explanted, contained identical alpha-chain TCR transcripts to those found to be clonally expanded in the coronary arteries from this patient. These results indicate that T cells infiltrating the epicardial arteries of cardiac allografts with chronic rejection undergo proliferation and clonal expansion in response to a specific antigen, which very likely is an (allo)antigen(s).