Biomedical subjects

O Ignatovich

Publications and source records attributed to O Ignatovich.

5 recordsLinked to original sources

PubMed2001

Molecular characterization of human monoclonal antibodies derived from fusions of tonsil lymphocytes with a human myeloma cell line.

Recently a new human myeloma cell line (Karpas 707H) has been developed for the efficient generation of stable human hybridomas. Here we describe the first molecular characterization of human monoclonal antibodies (MAbs) produced by a human counterpart to mouse myeloma cells. We studied 30 of the hybridomas generated by fusions to tonsil lymphocytes by DNA sequencing of rearranged V-genes, and have analyzed germ-line diversity, somatic hypermutation, and heavy- and light-chain pairings. Our results suggest that the hybridoma-derived antibodies are representative of antibodies from populations of human lymphocytes and at different stages in the maturation of the response; the use of Karpas 707H myeloma for human hybridoma fusions may therefore provide a valuable tool for analysis of the human antibody responses.

Amino Acid Sequence↗

PubMed1999

Dominance of intrinsic genetic factors in shaping the human immunoglobulin Vlambda repertoire.

The expressed human immunoglobulin Vlambda repertoire demonstrates a strong bias in the use of individual Vlambda segments. Mechanisms that underlie such biases can be divided into two categories: intrinsic genetic processes that lead to the preferential rearrangement and/or expression of certain segments; and selection following light chain expression. Here, we have used two approaches to investigate the factors that shape the human Vlambda repertoire. Firstly, we characterised 136 Vlambda rearrangements (59 productive and 77 non-productive) amplified from the human genomic DNA of peripheral blood cells. Secondly, we analysed Vlambda segment use in a library of 2000 cDNA clones from a transgenic mouse containing a 380 kb region (including 15 functional Vlambda segments) from the human immunoglobulin lambda locus. By hybridisation and sequencing we found that the patterns of use of human Vlambda segments in the transgenic mouse were similar to those found in the expressed human peripheral blood repertoire and in productive and non-productive genomic DNA rearrangements. These data indicate the importance of intrinsic genetic factors in shaping the human Vlambda repertoire and highlight the remarkable conservation of the molecular mechanisms involved in the production of the antibody repertoire in mouse and man. Therefore, transgenic mice represent a good model for analysis of the human antibody repertoire and for the production of human antibodies.

Animals↗

PubMed1997

The creation of diversity in the human immunoglobulin V(lambda) repertoire.

Sequence diversity in the human antibody repertoire is generated in two steps: by the combinatorial assembly of V gene segments and by somatic hypermutation. Here, we have characterised these processes for the lambda (lambda) light chain using a library of 7600 lambda cDNA clones from peripheral blood lymphocytes. By hybridisation and sequencing we found that most lambda chains are derived from the cluster of V(lambda) segments closest to the J(lambda)-C(lambda) pairs and that there is considerable variation in the use of individual V(lambda) segments (ranging from 0.02% to 27%): three of the 30 functional V(lambda) segments encode half the expressed V(lambda) repertoire. As a result of these biases, sequence diversity in the primary repertoire is focused at the centre of the antigen binding site. By contrast, somatic hypermutation spreads diversity to the periphery. Comparison with the human kappa (kappa) light chain indicates that both kappa and lambda use the same strategy for searching sequence space and have almost identical patterns of diversity in the mature antibody repertoire.

Gene Frequency↗

PubMed1996

Sequence and evolution of the human germline V lambda repertoire.

We recently completed a map of the human immunoglobulin lambda (IGL) locus on chromosome 22q11.2 and showed that the V lambda genes are arranged in three distinct clusters, each containing members of different V lambda families. We have now sequenced each of these V lambda genes and determined which are functional by comparison with the expressed repertoire. Our analysis indicates that there are approximately 30 functional V lambda genes, depending on the haplotype, that belong to ten V lambda families (five V lambda 1, five V lambda 2, eight V lambda 3, three V lambda 4, three V lambda 5, one V lambda 6, two V lambda 7, one V lambda 8, one V lambda 9 and one V lambda 10). V lambda genes related to the major human V lambda families (V lambda 1, V lambda 2 and V lambda 3) predominate in species that express mainly lambda light chains.

Amino Acid Sequence↗

PubMed1995

Cloning and characterisation of the gene encoding the ribosomal protein S5 (also known as rp14, S2, YS8) of Saccharomyces cerevisiae.

The protein sequence derived from a cloned yeast gene and partial cDNA has high sequence identity to 40S ribosomal subunit S5 proteins of higher eukaryotic origin. The open reading frame of the gene is flanked by consensus sequence motifs characteristic of ribosomal protein genes and the pattern of transcription of the gene in yeast cells subjected to nutritional shift or temperature shock is also typical of a ribosomal protein gene. The gene is single copy and essential for viability. The predicted sequence of the N-terminus of the protein identifies it as a phosphorylated ribosomal protein variously known as rp14, S2 or YS8, the least basic of the non-acidic ribosomal proteins of Saccharomyces cerevisiae.

Amino Acid Sequence↗