Sequential G-banding and fluorescent in situ hybridization on peripheral blood, bone marrow, and amniotic fluid samples

High efficiency creation of human monoclonal antibody-producing hybridomas

The native human antibody repertoire holds unexplored potential for the development of novel monoclonal antibody therapeutics. Current techniques that fuse immortal cells and primary B-lymphocytes are sub-optimal for the routine production of hybridomas that secrete human monoclonal antibodies. We have found that a murine cell line that ectopically expresses murine interleukin-6 (mIL-6) and human telomerase (hTERT) efficiently forms stable human antibody-secreting heterohybridomas through cell fusion with primary human B-lymphocytes. The hybrid cells maintain secretion of human antibodies derived from the primary B-lymphocytes through multiple rounds of cloning. Using splenic B-lymphocytes from a patient immunized with a Streptococcus pneumoniae capsular polysaccharide vaccine, we have succeeded in creating hybridomas that secrete human monoclonal antibodies specific for S. pneumoniae antigens. Using peripheral blood lymphocytes, we have similarly cloned a human antibody that binds a viral antigen. These experiments establish that SP2/0-derived cell lines ectopically expressing mIL-6 and hTERT will enable the rapid cloning of native human monoclonal antibodies.

IGH gene involvement in two cases of acute lymphoblastic leukemia with t(14;14)(q11;q32) identified by sequential R-banding and fluorescence in situ hybridization

Translocation (14;14)(q11;q32) or inv(14)(q11q32) is a common cytogenetic aberration in T-cell leukemia associated with ataxia-telangiectasia (AT); however, rare reports have indicated that this abnormality also occurs in B-lineage acute lymphoblastic leukemia (ALL). We report here two cases with common-type ALL exhibiting the chromosomal aberration t(14;14)(q11;q32). The immunophenotype showed the blasts were positive for CD9, CD10, CD38, CD22, and CD15 in case 1 and positive for CD2, CD9, CD10, CD19, CD38, CD20, and CD22 in case 2, but negative for CD3, CD4, and CD8 expression in both cases. The cytogenetic analysis revealed del(6)(q22), and t(14;14)(q11;q32) in case 1 and t(14;14)(q11;q32),+mar in case 2. Fluorescence in situ hybridization (FISH) and sequential R-banding FISH assay with dual-color break-apart IGH probe confirmed that t(14;14)(q11;q32) involved the IGH gene in our cases. The results indicate that the t(14;14)(q11;q32) involving IGH at 14q32 in B-lineage ALL in our cases differ from those reported to involve the TCL1 gene on 14q32.1 in T-cell leukemia associated with AT. Sequential R-banding and FISH provide precise analysis of alterations of chromosomes and genes involved.

Detailed genome-wide screening for inter- and intrachromosomal abnormalities by sequential G-banding and RxFISH color banding of the same metaphase cells

While the now-classic chromosome banding methods, such as G-banding, remain the techniques of choice for the initial screening for karyotypic abnormalities, sometimes chromosomal rearrangements involve segments too small or too similarly banded to be detected or described adequately by these techniques. The necessity to use a genome-wide, fluorescence in situ hybridization (FISH)-based screening technique as a complement to G-banding is especially obvious in cases where the information obtained by the latter analysis does not provide an adequate guide to the choice of probes for chromosome-specific FISH. Furthermore, the same metaphase cells should ideally be used for both G-banding and FISH analysis to overcome the scarcity of metaphases observed in many cases and to ensure the correct interpretation of chromosomal aberrations in cytogenetically unstable neoplasms with massive cell-to-cell karyotypic variability. We describe a protocol which enables cross-species color banding (RxFISH), a new FISH-based screening technique that simultaneously imparts specific color banding patterns on all chromosomes, of preparations that have been G-banded and mounted for up to several years, as well as a procedure allowing chromosome-specific painting of the same metaphase cells to resolve whatever doubts persist after the preceding G-banding and RxFISH analyses. This approach makes possible a detailed, genome-wide screening for inter- and intrachromosomal abnormalities including archival cases whose karyotypic rearrangements had been incompletely identified by G-banding.