Hybridomas synthesizing monoclonal antibodies to surface antigens of human lymphocytes

Three types of hybridomas were obtained by fusion of murine myeloma cells (NSI-1-Ag4-1) with splenocytes from mice immunized with human lymphoblastoid cells (RPMI-6410t line, acute myeloblastic leukemia). Hybridomas of the first type synthesize monoclonal antibodies Ma-1, which interact with 6410t-cells, but are not bound to the cells of human Burkitt lymphoma-Raji. Raji cells contain HLA-DRw5 and -DRw6 antigens on cell surface but there are no HLA-A2, -B7 and -B12 antigens (specific for 6410t). Thus, Ma-1 are probably derected against some of HLA antigens of loci A or B. Hybridomas of the second type synthesize Ma-2 antibodies which react with 6410t and Raji cells, but are not bound to peripheral blood lymphocytes (PBL). We suppose that Ma-2 antibodies to tumor specific antigens which have common antigen determinants both for Raji and RPMI-6410t cells. The third type of hybridomas synthesizes monoclonal antibodies Ma-3 reacting with all the three types of target cells: 6410t, Raji, and PBL. Ma-3 seems to be directed against human species-specific lymphocyte antigens which remained in 6410t and Raji cells.     

Biotechnological Potential of the Bacillus subtilis 20 Strain

Molecular Biology - Bacillus subtilis bacteria play an important role in veterinary medicine, medicine, and biotechnology, and the permanently growing demand for biotechnological products fuels the...     

Comparison of the homologous SfeI and LlaBI restriction-modification systems

A fragment containing the SfeI restriction-modification system (RMS) operon was cloned from a Streptococcus faecalis SE72 plasmid. Nucleotide sequence analysis revealed its high (99.2%) homology to the operon for Lactococcus lactis subsp. cremoris W56 LlaBI RMS recognizing the same site, 5'-CTRYAG-3'. A substantial difference was that SfeI RMS operon had an additional 198-bp fragment and a larger gene for the putative control protein. No homology was observed between operon-flanking sequences of the two closely related species, suggesting horizontal transfer of the operon.     

Complete protection against melanoma in absence of autoimmune depigmentation after rejection of melanoma cells expressing α(1,3)galactosyl epitopes

The major barrier for xenotransplantation in humans is the presence of (1–3) Galactosyl epitopes (Gal) in xenogeneic tissue and the vast quantities of natural antibodies (Ab) produced by humans against this epitope. The binding of anti-Gal Ab to cells expressing Gal triggers a complement-mediated hyperacute rejection of target cells. The hyperacute rejection of whole cancer cells, modified to express Gal epitopes, could be exploited as a new cancer vaccine to treat human cancers. We tested this hypothesis in Galactosyltransferase knockout (GT KO) mice which, like humans, do not express Gal on their cell surfaces and can produce anti-Gal Ab. Forty-five percent of mice with preexisting anti-Gal Ab rejected Gal positive melanoma cells (B16Gal). These mice remained tumor-free for more than 90 days. The majority of control mice injected with B16Null, Gal negative cells succumbed to melanoma. The rejection of B16Gal induced strong long-lasting antitumor immunity against B16Null measured by the expansion of cytotoxic T lymphocytes. In addition, mice rejecting B16Gal were protected against melanoma since they survived a second rechallenge with B16Null. Protected mice developed antitumor immunity in the absence of autoimmune depigmentation (vitiligo). These results show that rejection of Gal positive melanoma cells can efficiently boost the immune response to other tumor associated antigens present in Gal negative melanoma cells. This study supports the concept of a novel anticancer vaccine to treat human malignancies.     

New and previously unknown Eurytomidae (Hymenoptera) species from Yemen

Ten new species of the genera Eurytoma (8 species) and Tetramesa (2 species) from Yemen are described (Eurytoma lahji Zerova, E. thoraxica Zerova, E. cyrtophorae Zerova, E. longipes Zerova, E. yemeni Zerova, E. mabari Zerova, E. tibiaspinae Zerova, E. longitarsis Zerova, Tetramesa sanai Zerova, and T. rujumi Zerova). The type specimens of the new species are deposited in the collection of the Institute of Zoology, National Academy of Sciences of Ukraine, Kiev.     

New species of chalcidoid wasps of the family Eurytomidae (Hymenoptera,Chalcidoidea) from arid Palaearctic regions

Five new species of chalcidoid wasps of the family Eurytomidae are described: four from Israel and one from Kazakhstan. Tetramesa pavliceki Zerova, sp. n. (cylindrica species group) is closely related to T. scheppugi Schlecht., but differs in the more elongate flagellar segments, longer genae, and smooth metasomal tergites. Eurytoma nevoi Zerova, sp. n. is similar to E. sabulosa Erd. and E. bicolorata Zer. (phragmiticola species group), differs from these species in the longer marginal vein, punctate propodeum, and longer flagellar segments. E. oreni Zerova, sp. n. belongs to the fumipennis species group. It is closely related to E. monticola Zer., but differs in the more convex scape, longer postmarginal vein, and yellow legs. E. simutniki Zerova, sp. n. belongs to the robusta species-group. It resembles E. heriadi Zer., but differs in the longer flagellar segments of the female and in the shorter postmarginal vein. Nikanoria mamayevi Zerova, sp. n. is similar to N. stigma Zer., but differs in the more elongate metasoma, longer flagellar segments of both sexes, and larger yellow spots on the pronotum.     

Biochemically labelled human lymphoblastoid cell line. I. Its karyotypic, growth and physiological characteristics

A study was made of the properties of human lymphoid cell line RPMI-6410 derived from peripheral blood of a patient with acute myeloblastic leukaemia. The lymphoblastoid cell line was found to be resistant to 5-brom-deoxyuridine and to have a low thymidine kinase activity. The modal chromosome number for RPMI-6410 is 46-47 XY. The karyotype includes marker chromosomes: two large submetacentrics --M1 and M2, and two small acrocentrics--M3 and M4. Ways of marker chromosome formation are discussed. The properties of RPMI-6410 line make it possible to use it for somatic cell hybridization, in particular, for obtaining hybridoma synthesizing human monoclonal antibodies.     

Reversible suppression and activation of immunoglobulin genes in differentiated IgG+ sublines of human RPMI-6410t B-cells

Differentiated human B-cells of the IgG+ sublines obtained as a result of switching from IgM to IgG synthesis in the 6410t line and its IgM+ lines gradually reduce the level of IgM secretion after the inductor removal. IgG synthesis can be partially or fully recovered by treating the IgG+ sublines with a polyclonal activator of B-lymphocytes, lipopolysaccharide W from Gram negative bacteria. In the conditions of certain regulatory effects, differentiated IgG+ cells are capable to pass reversibly in the state of functional rest and synthesis initiation.