Biomedical subjects

I Kokkelink

Publications and source records attributed to I Kokkelink.

4 recordsLinked to original sources

PubMed1992

Purification and characterization of two lipoxygenase isoenzymes from germinating barley.

Two lipoxygenase isoenzymes (linoleate: oxygen oxidoreductase, EC 1.13.11.12) present in the embryo of germinating barley seed have been purified to homogeneity and characterized. Both isoenzymes are monomeric proteins with a molecular mass of approx. 90 kDa and crossreact on Western blots with antibodies raised against pea lipoxygenase. They have an apparent Km of approx. 16 microM for linoleic acid. The isoenzymes differ in the product formed upon incubation with linoleic acid. One of the isoenzymes (lipoxygenase 1) solely forms the 9-HPOD as a product whereas the 13-HPOD is the major product formed by the other isoenzyme (lipoxygenase 2). Lipoxygenase 1 shows a pH-optimum of 6.5, is active in a broad pH range and has an isoelectric point of 5.2-5.3. Lipoxygenase 2 has the same pH optimum, but is active in a narrow pH range and has a significantly higher pI, namely 6.8-6.9. The occurrence of two isoenzymes was confirmed by peptide analysis of the proteins. Amino acid sequence data obtained from proteolytic fragments of lipoxygenase 1 show up to 50% identity with other plant lipoxygenases.

Amino Acid Sequence↗

PubMed1990

Relative increase of inflammatory CD4+ T cells in the cerebrospinal fluid of multiple sclerosis patients and control individuals.

Of three patients with multiple sclerosis (MS) and two non-MS individuals a large number of CD4+ T cell clones was obtained from the cerebrospinal fluid and peripheral blood by direct limiting dilution. The CD4+ T cell clones from cerebrospinal fluid and peripheral blood lymphocytes were compared for their cytotoxic activity and lymphokine production. Cytotoxic capacity of cloned T cells was analysed with the use of anti-CD3 antibodies and target cells bearing Fc receptors for murine IgG. Recently, we demonstrated the existence of two different subsets of human CD4+ T cell clones by phenotypic and functional criteria. One type of CD4+ T cell with anti-CD3 mediated cytotoxic activity, in analogy with murine studies, is the inflammatory or TH1 subtype, the main producer of interleukin (IL-2), interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF)-alpha, -beta, whereas the other type of CD4+ T cell clone lacked anti-CD3 mediated cytotoxicity and produced minimal amounts of IL-2 concomitant with reduced levels of IFN-gamma and TNF-alpha, -beta. The present study demonstrates that among three MS patients, relatively more inflammatory CD4+ T cell clones with cytotoxic activity and IFN-gamma and TNF-alpha, -beta production were derived from the cerebrospinal fluid as compared with peripheral blood lymphocytes. Also among control individuals more inflammatory CD4+ T cell clones could be obtained from the cerebrospinal fluid as from the peripheral blood. The enrichment of inflammatory CD4+ T cells, therefore, appears to be physiological rather than associated with the disease.

CD4-Positive T-Lymphocytes↗

PubMed1988

Clonal analysis of functionally distinct human CD4+ T cell subsets.

A large number of CD4+ T cell clones, obtained from peripheral blood T lymphocytes by direct limiting dilution, allowed us to address the question whether functional heterogeneity exists within the human CD4+ T cell subset. Cytotoxic capacity of cloned T cells was analyzed with the use of anti-CD3 antibodies and target cells bearing FcR for murine IgG. 6 of 12 CD4+ clones obtained were able to lyse Daudi or P815 cells in the presence of anti-CD3 antibodies. The remaining six CD4+ T cell clones tested did not display anti-CD3-mediated cytotoxic activity and did not acquire this cytotoxic capacity during a culture period of 20 wk. In the absence of anti-CD3 mAb, no lytic activity against Daudi, P815, and K562 target cells was observed under normal culture conditions. Phenotypic analysis of these two distinct types of CD4+ T cells did not reveal differences with regard to reactivity with CDw29 (4B4) and CD45R (2H4) mAbs that have been described to recognize antigens associated with helper suppressor/inducer (respectively) CD4+ cells. The CD4+ clones without anti-CD3-mediated cytotoxic activities (Th2) consistently showed a high expression level of CD28 antigens, whereas the cytotoxic clones (Th1) expressed low amounts of CD28. Th1 CD4+ clones did produce IL-2, IFN-gamma, and TNF-alpha/beta, whereas the Th2 T cell clones produced minimal amounts of IL-2 and only low levels of INF-gamma and TNF-alpha/beta in response to anti-CD3 mAbs and PMA. Although not all CD4+ clones did release IL-4, there was no correlation with cytotoxic activity. Moreover, as compared with the Th1 CD4+ clones, Th2 CD4+ T cell clones proliferated moderately in response to immobilized anti-CD3 mAbs. However, proliferation reached the level of the cytotoxic clones when anti-CD28 mABs were present during culture. Both CD4+ subsets provided help for B cell differentiation upon stimulation with anti-CD3 mAbs. Our data suggest that the human CD4+ subset, in analogy to the murine system, comprises two functionally distinct T cell subpopulations, both of which are able to exert helper activity for polyclonal B cell differentiation, but which differ in cytotoxic capacity, lymphokine production, and requirements for proliferation. A function for these two types of T cells in the immune response is discussed.

Antigens, Differentiation, T-Lymphocyte↗

PubMedDate not supplied

Analysis of T cell receptor-gene rearrangement in T cells from the cerebrospinal fluid of patients with multiple sclerosis.

Characterization of T cells present in the cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) may contribute to an understanding of the immunopathologic role of these cells. To analyze the T cells in the CSF of MS patients, 30 cloned T cell lines from each of two MS patients were surveyed for their patterns of T cell receptor (TcR) beta-chain gene rearrangement. DNA from the (CSF-derived) T cell clones was digested with a number of restriction endonucleases and the gene rearrangement patterns were analyzed with a T cell receptor beta-chain probe. Southern blot analysis of the DNA of these T cell clones indicated that all had rearrangements of the TcR beta-chain genes, but none of the rearrangements were identical. These results suggest that, if a few clones of specific T cells are involved, they must form a tiny minority in comparison to the total number of T cells in the CSF of MS patients.

Adult↗