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A Hinkkanen

Publications and source records attributed to A Hinkkanen.

10 recordsLinked to original sources
PubMed1992

Diversity of T cell receptor alpha and beta chain genes expressed by human T cells specific for similar myelin basic protein peptide/major histocompatibility complexes.

T cell receptor (TcR) alpha and beta nucleotide sequences involved in the human autoreactivity to myelin basic protein (MBP) were studied by screening cDNA libraries derived from 11 independent T lymphocyte clones (TCC) established from multiple sclerosis patients and healthy donors. The TCC with defined MBP peptide specificity and HLA-DR restriction expressed multiple TcR. Even TCC recognizing the same human MBP peptide [amino acids (aa) 139-153] in identical or very similar HLA-DR context expressed diverse TcR. Two TCC which recognized peptide aa 139-153 equally well in the context of both HLA-DR2a and -DR1 molecules used distinct TcR alpha but identical beta chains. The knowledge of TcR beta and TcR alpha chain sequences of human MBP-specific T cells will allow studies correlating structure and function of TcR and their targets in MBP autoreactivity. This may have an impact on the development of immunotherapies in multiple sclerosis.

Amino Acid Sequence↗
PubMed1990

Rapid method based on reversed-phase high-performance liquid chromatography for purification of human myelin basic protein and its thrombic and endoproteinase Lys-C peptides.

Reversed-phase high-performance liquid chromatography was applied to isolate myelin basic protein from human brain, followed by separation of proteolytic peptides thereof on the same chromatographic system. Brain tissue was delipidated under conditions that keep copurifying proteases inactive. The crude brain protein fraction was applied directly to a C4 column. The homogeneous protein obtained in this way was digested with thrombin and endoproteinase Lys-C in order to produce short defined myelin basic protein peptides. The purified peptides were used to determine the antigen fine specificity of myelin basic protein recognizing T lymphocyte lines isolated from multiple sclerosis patients.

Brain Chemistry↗
PubMed1990

Myelin autoreactivity in multiple sclerosis: recognition of myelin basic protein in the context of HLA-DR2 products by T lymphocytes of multiple-sclerosis patients and healthy donors.

A panel of 20 human myelin basic protein (hMBP)-specific T-lymphocyte lines was generated from the peripheral blood of eight multiple sclerosis (MS) patients and two healthy donors, most of them expressing the HLA-DR2 haplotype, which is associated with an increased susceptibility to MS. Using HLA-DR gene-transfected mouse L-cell lines as antigen-presenting cells, we established that of the 20 hMBP-specific T-lymphocyte lines, 7 were restricted by the DR2a gene products of the DR2Dw2 haplotype. Four T-cell lines recognized hMBP in the context of the DR2b products of the DR2Dw2 haplotype. DR2b-restricted T-cell responses were demonstrable only in T-cell lines derived from MS patients. The hMBP epitopes presented by the DR2a heterodimer were mapped to peptides covering amino acid residues 1-44, 76-91, 131-145, or 139-153 and to a region spanning the thrombin-cleaved bond at Arg130-Ala131. DR2b-restricted T-cell lines recognized epitopes within amino acids 80-99 and 148-162. Peptide 139-153 was also presented in the context of HLA-DR1 molecules. Our data show that (i) in MS patients both the DR2a and DR2b products of the DR2Dw2 haplotype function as restriction elements for the myelin autoantigen hMBP, (ii) the DR2a molecule presents at least five different epitopes to hMBP-specific T lymphocytes, and (iii) anti-hMBP T-cell lines derived from individual donors can differ in their antigen fine specificity as well as in their HLA restriction.

Adult↗
PubMed1987

Mammalian T-lymphocyte antigen receptor genes: genetic and nongenetic potential to generate variability.

T lymphocytes of higher vertebrates are able to specifically recognize a seemingly unlimited number of foreign antigens via their receptors, the T cell antigen receptors (TCRs). T lymphocytes mature by passing through the thymus and acquire antigen specificity by expressing the TCR molecules on their cell surface. Genetic and somatic diversification mechanisms give rise to the enormous degree of TCR variability observed in mature T cells: germline and combinatorial diversity as well as junctional and the so-called N-region diversity. In contrast to the situation in immunoglobulin genes somatic hypermutation does not seem to play a significant role in TCR diversification. It is argued here that the enzyme terminal nucleotidyl-transferase is potentially a major factor in generating the immense diversity. We propose furthermore that this enzyme ensures the flexibility of T cell responses to novel antigens by random insertion of so-called N-region nucleotides. Apart from the physiological functions of TCR genes any involvement in the etiology of T cell neoplasia remains to be proven.

Animals↗
PubMedDate not supplied

Oligonucleotide fingerprinting with (CAC)5: nonradioactive in-gel hybridization and isolation of individual hypervariable loci.

The first topic to be treated in this paper is the nonradioactive DNA fingerprinting by means of in-gel hybridization with digoxigenated (CAC)5. Besides the fact that time-consuming Southern blotting can be avoided, the dried agarose is an excellent matrix to produce background-free nonradioactive DNA fingerprints. There is no tendency of either the oligonucleotide probe or the antibody towards unspecific binding to the dried agarose. Prehybridization and blocking steps are therefore superfluous. Furthermore, we will discuss what effect the degree of crosslinking of the antibody-enzyme conjugates has. The second topic concerns the isolation and characterization of locus-specific probes from a human (CAC)5 fingerprint. The isolation and characterization of one variable probe, by screening complete genomic libraries, is described and discussed. This probe is compared to a hypervariable single-copy probe, isolated from a size-enriched genomic library. The sequence of the repeat flanking locus-specific probe is presented and a semi-specific, adaptor-mediated polymerase chain reaction was designed to amplify (CAC)n/(GTG)n flanking sequences.

Base Sequence↗
PubMedDate not supplied

Highly instable (GATA)n-containing sequences of the mouse during the cloning process.

Mouse DNA fingerprints were obtained by HaeIII digestion of genomic DNA and in-gel hybridization with the (GATA)4 oligonucleotide probe. In order to obtain locus-specific probes that hybridize with only one fragment of the (GATA)4 DNA fingerprint, a genomic library of size-selected inserts was constructed using a system of direct subcloning from the phage clones. During the cloning procedure, the phage as well as the plasmid insert DNAs changed primarily within their repetitive DNA but also within adjacent nonrepetitive sequences, as was demonstrated for several clones by in-gel hybridization with the (GATA)4 probe as well as by sequence analysis. Isolated subclones varied within their (GATA)n repeats, resulting in different insert lengths. Several "metastable" as well as stable (GATA)4-positive subclones could be isolated. Also, vector sequences were affected by alterations during the cloning process. These phenomena are discussed within the context of possible mechanisms for cloning artifacts.

Animals↗