Human endothelial culture supernatant selectively promotes IgM-producing hybridomas.

We compared the effect of human endothelial cell culture supernatant (HECS), ESG (Ewing sarcoma growth factor), IL-6 (interleukin-6) and peritoneal macrophages on the recovery of hybridoma cells after fusion with respect to growth, stability and distribution of isotype variants. A selective growth of murine IgM-producing hybridoma cells was observed in the presence of HECS after cell fusion.

Modulation of CD4 lateral mobility in intact cells by an intracellularly applied antibody.

This study shows that the lateral mobility of CD4, an important plasma-membrane immune receptor, can be modulated by intracellular application of an anti-CD4 antibody. For this purpose, (i) full-length CD4 and a truncated CD4 mutant, lacking a 32-residue-long C-terminal intracellularly exposed domain, were expressed in Spodoptera frugiperda (Sf9) insect cells, (ii) a monoclonal antibody, C6, with specificity for the C-terminal domain was generated, and (iii) a versatile apparatus for fluorescence microphotolysis (FM) studies was constructed. By these means it was found that the commercial anti-CD4 antibody Leu3a-PE, in contrast with several other anti-CD4 antibodies, could be used as a fluorescent label of CD4 without interfering greatly with CD4 mobility.

Immune response against the murine mdri protein induced by vaccination with synthetic lipopeptides in liposomes.

Intrinsically, or after exposure to chemotherapeutic drugs, many cancer cells overexpress a class of high molecular weight membrane glycoproteins associated with the multidrug resistance (mdr) of these cells. This report describes an immunization protocol eliciting autoantibodies specific to extracellular epitopes of the murine mdr 1 P-glycoprotein (Pgp). Synthetic peptides with the sequences of extracellular loops of murine Pgp were covalently coupled with four palmitic acid moieties per peptide molecule.

Low-oxygen-affinity red cells produced in a large-volume, continuous-flow electroporation system.

Background: Human red cells containing inositol hexaphosphate (IHP) have a lowered O2 affinity, though they are able to bind and carry about the same amount of oxygen as native cells. These modified cells therefore deliver oxygen more efficiently to the tissues, which is a property of potential clinical utility. Investigators set out to devise a system and procedure by which large volumes of IHP-containing red cells, suitable for transfusion, could be produced quickly and efficiently.

Signal transduction in SF9 insect cells: endocytosis of recombinant CD4 after phorbol ester treatment.

In Spodoptera frugiperda (Sf9) insect cells infected with a recombinant baculovirus carrying a gene construct encoding human CD4 endocytosis of CD4 is induced after stimulation with phorbol-12-myristate-13-acetate (PMA). Stimulation of endocytosis with PMA reduced the amount of full-length CD4 on the plasma membrane of Sf9 cells by 50% after 2 hours. Endocytosis of CD4 is blocked after intracellular delivery by cationic liposomes of a monoclonal antibody directed against a cytoplasmic sequence of CD4.

Nucleated cells response to protein electroinsertion.

Application of an electrical pulse field at a strength slightly below the value required for electroporation to a suspension of red blood cells in the presence of membrane xenoproteins leads to the insertion of those proteins in the erythrocyte plasma membrane. This observation is extended to nucleated cells. In the presence of glycophorin A, application of such pulses leads to the insertion of 10(4)-10(5) molecules of glycophorin A per cell in CEM-CM3, Hela S3, and bovine CD8+ T cells.