Colcemid treatment of myeloma prior to cell fusion increases the yield of hybridomas between myeloma and splenocyte

New approaches for the development and application of monoclonal antibodies for the diagnosis and therapy of human cancer

Monoclonal antibodies (MAbs) represent potentially important reagents for both the diagnosis and therapy of human cancer. Innovative approaches are resulting in the improved production of MAbs and an enhanced ability to use these molecules therapeutically. Application of genetic engineering to MAb development is also resulting in the production of MAbs displaying enhanced target specificity. Of particular value for cancer therapy will be catalytic, bispecific, anti-idiotypic and human MAbs. By using agents that can augment the expression of tumor-associated antigens on cancer cells, a further increase in the utility of MAbs in cancer therapy will be forthcoming.

Detection of Salmonella enteritidis in environmental samples by monoclonal antibody-based ELISA

We have developed a enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (ASCII) for the detection of Salmonella enteritidis in environmental samples. ELISA was used to test for sensitivity and specificity of ASCII. 38 other species of bacteria, including 31 Salmonella species were included in cross-reactivity testing with ELISA. ASCII showed no reactivity with any other species tested. ASCII was found to be an IgG1 specific for S. enteritidis lipopolysaccharide (LPS). The lower limits for S. enteritidis detection was 10(5) cells/ml for pure cultures and in 10% sludge (w/v). Environmental samples (raw wastewater, wastewater effluents, mixed liquor and aerobically digested sludge) were obtained twice from five sites and ELISA tested for the presence of S. enteritidis. ELISA results compared to the American Public Health Association (APHA) method of Salmonella detection were not significantly different (P greater than 0.05). The ELISA took 24 h for completion compared to 96-120 h for the APHA procedure. Results demonstrate the reliability of the ELISA and, more importantly, provides a rapid means of detection of S. enteritidis in environmental samples.

Enzyme-linked immunosorbent assays for kinins using high-affinity monoclonal kinin antibodies

Splenocytes from mice immunized either with bradykinin conjugated with carbodiimide to keyhole limpet hemocyanin or ovalbumin were fused using polyethylene glycol with the mouse myeloma cell line SP2/o. Nine monoclonal antibodies reactive with kinins were obtained from two fusions. All of the antibodies were of the IgG1k isotype, except for one, which was an IgG2ak. Based on their reactivities with biologically active kinins and biologically inactive degradation products, the antibodies were separated into three groups. The first group, which had the highest affinities for bradykinin, displayed about equal reactivities for bradykinin and des-Arg9-bradykinin, but little reactivities for the kinin fragments, des-Arg1-bradykinin and des-Phe8-Arg9-bradykinin, or for lysyl-bradykinin and methionyl-lysyl-bradykinin. The second group was similar to the first except that it showed about a 2.5- to 3.5-fold greater reactivity for des-Arg9-bradykinin than for bradykinin. The third group, which had the lowest affinities for bradykinin [50% inhibition of antibody binding to an enzyme-linked immunosorbent assay (ELISA) plate occurring with bradykinin concentrations ranging from about 8 to 39 nM], showed little reactivities with des-Arg1-bradykinin, des-Arg9-bradykinin and des-Phe8-Arg9-bradykinin, but 50-100% cross-reactivities with lysyl-bradykinin and methionyl-lysyl-bradykinin. The useful ranges for bradykinin detection (ng/well, 50 microL assay volume) using the highest affinity antibody in each group in ELISAs were: 0.01 to 0.5, 0.03 to 3, and 0.1 to 3 for groups 1, 2, and 3, respectively.

High yields of specific hybridomas obtained by electrofusion of murine lymphocytes immunized in vivo or in vitro

We have studied the use of electrofusion to obtain hybridomas producing antigen-specific antibodies after immunization of murine lymphocytes in vitro. Under optimal conditions fusion frequencies of the order of magnitude of 10(-3) were obtained, which is approximately 80-fold higher than the mean value obtained with fusion induced by polyethylene glycol. The number of antigen-specific hybridomas was also increased in a comparable way. The high yields of specific hybridomas observed with electrofusion were independent of the immunization procedure, the antigen or the hapten of interest, or the sources of the lymphocytes. The data presented in this paper indicate that electrofusion may be an extremely attractive alternative method for immortalization of human lymphocytes following immunization in vitro.

Cytoskeletal reorganization during electric-field-induced fusion of Chinese hamster ovary cells grown in monolayers

Mammalian cells were shown to fuse after direct electric pulsation of the plated cells in culture. The extent of fusion was controlled by the duration of the post-pulse incubation. Formation of polynucleated cells was slow, even at 37 degrees C. Pre-pulse incubation with colchicine increased the fusion yield slightly. Cytoskeletal organization during the post-pulse incubation was observed using immunofluorescence techniques. Microfilaments were unaffected, but microtubules disappeared during the first minutes following the pulse, and then reformed on subsequent incubation.

Isolation of a rat liver delta-aminolevulinate dehydrase (ALAD) cDNA clone: evidence for unequal ALAD gene dosage among inbred mouse strains

We have isolated several cDNA clones encoding delta-aminolevulinate dehydrase [ALAD; porphobilinogen synthase; 5-aminolevulinate hydro-lyase (adding 5-aminolevulinate and cyclizing), EC 4.2.1.24], the second enzyme in the heme biosynthetic pathway. We used a rabbit polyclonal antibody developed against the purified 35-kDa subunit of rat liver ALAD to screen a lambda gt11 cDNA expression library constructed from rat liver mRNA. A prototype clone (ALAD-1) contained a 680-base-pair insert and expressed a 140-kDa beta-galactosidase gene cDNA insert fusion protein immunoreactive with both polyclonal and monoclonal anti-ALAD. Identity of ALAD-1 was verified by hydridization to ALAD mRNA that had been enriched via immunopurification of rat liver polysomes with anti-ALAD. Intensity of such hybridization to a 1500-nucleotide-long mRNA was approximately equal to 200-fold greater than that realized with whole liver mRNA, a result consistent with the degree of immunoenrichment of ALAD mRNA found independently by analysis of cell-free translation products. A second ALAD cDNA clone (ALAD-3) was isolated when the rat liver cDNA expression library was rescreened with ALAD-1. The identity of both ALAD cDNA clones was established by correspondence between their nucleotide sequence and the reported amino-terminal protein sequence of bovine ALAD. Hybridization of ALAD cDNA to mouse genomic DNA indicates that the previously unexplained incremental differences in ALAD enzymatic activity among inbred mouse strains has arisen through alterations in ALAD gene dose.