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Biomedical subjects

D Rigal

Publications and source records attributed to D Rigal.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

T lymphocyte disorder after Capnocytophaga ochracea endocarditis.

Capnocytophaga species are gram-negative rods which may cause disease in both non-immunocompromised and immunocompromised hosts. We describe a case of endocarditis due to Capnocytophaga ochracea in a non-immunocompromised patient with a decrease of blood CD4/CD8 ratio and lymphocyte proliferative response to ConA during infection. In vitro experiments showed that C. ochracea decreased lymphocyte proliferation to mitogens (ConA, PHA), cell surface CD4 antigen and IL2 receptor expression on peripheral blood mononuclear cells (PBMC) from normal volunteers.

Capnocytophaga↗
PubMedDate not supplied

Canine monocytes express a receptor specific for murine Fc gamma 2a and Fc gamma 3 immunoglobulins.

Murine monoclonal antibodies (mAb) of IgM and IgG subclasses that do not bind to canine cells have been used to detect the expression of Fc receptors on canine peripheral blood mononuclear cells and the cell line MAXEY-DH82. Murine Ig of IgG2a and IgG3 isotypes bound specifically to canine peripheral blood monocytes and to MAXEY-DH82, whereas Ig of IgG1, IgG2b, and IgM did not. No other cell types, including resting and activated peripheral blood lymphocytes, expressed this canine Fc receptor (cFcR) specific for murine IgG2a and IgG3. MAXEY-DH82 was used to characterize this Fc gamma 2a/gamma 3 receptor. Binding of murine IgG2a and IgG3 is trypsin sensitive and partially suppressed by phosphatidyl inositol-phospholipase C (PI-PLC) treatment, indicating that this cFc gamma 2a/gamma 3 receptor is a lipid-anchored protein. Preincubation of MAXEY-DH82 with canine sera or canine IgG prevented the binding of murine gamma 2a/gamma 3 Ig, demonstrating that this receptor is a cFc receptor for canine IgG. The cFc gamma R expressed on canine monocytes and on MAXEY-DH82 is probably the analog of the murine and human Fc gamma RI. The specific expression of this analog by canine cells could be used in identifying and purifying canine monocytes.

Animals↗
PubMedDate not supplied

Differential expression of the LFA-1 molecule on the human peripheral blood mononuclear cell subpopulations.

The expression of leukocyte function associated antigen 1 (LFA-1) was studied on human peripheral blood mononuclear cells (PBMNC) by a double immunofluorescence method. Monoclonal antibodies IOT18 (recognizing the beta chain, 95 kDa, CD18) and SPVL7 (recognizing the alpha chain, 180 kDa, CD11a) were used. These antibodies revealed the same heterogeneous distribution of the LFA-1 molecule among peripheral blood mononuclear cells. A bimodal profile characterized the lymphocytes, whereas the monocyte subpopulation presented a unimodal profile. NK cells, including CD16, CD8 dim, expressed the LFA-1 with a high density. B cells expressing the CD19 phenotype showed surface LFA-1 at a low level, whereas it appeared with an intermediate intensity on the T helpers/inducers (CD4 cells). Among the cytotoxic cells (CD8) and the immunoregulatory subpopulations associated with an immunosuppressive response (CD8+ CD11b+, CD8+ CD11b- and CD8+ leu8+) or with a contrasuppressive response (Vicia villosa cells), an heterogeneous LFA-1 expression was observed, discriminating the LFA-1 dim and the LFA-1 bright cells. Anti LFA-1 antibodies also allowed us to define three novel subsets among the CD8 cells: the CD8 dim LFA-1 bright, the CD8 bright LFA-1 bright, and the CD8 bright LFA-1 dim cell subpopulations. This heterogeneous distribution of LFA-1 among PBMNC may be associated with different functions of the different cell subsets analyzed in this study.

Antibodies, Monoclonal↗
PubMedDate not supplied

Methylation patterns of long interspersed repeated DNA and alphoid repetitive DNA from human cell lines and tumors.

The methylation status of CCGG sites has been determined in long interspersed repeated (L1Hs sequences) DNA and in alphoid satellite DNA extracted from human cell lines and also from pathological specimens. Southern blot experiments were performed using a cloned 1.2 kb KpnI fragment of L1Hs DNA and a cloned 680 bp tetrameric unit of alphoid satellite. DNA as probes for these sequences. In vitro transformation of human lymphocytes by Esptein-Barr virus is correlated with a progressive hypomethylation of L1 Hs DNA sequences. This loss of modification of L1 sequences is also observed in DNA isolated directly from colon adenocarcinoma and in chronic lymphocytic leukemia. Therefore, alteration of the level of methylation of L1 sequences seems not to be due solely to in vitro cultivation of human cells but is associated with the immortalization of these cells. In addition, these sequences are preferentially hypomethylated when compared to alpha-satellite DNA in several lymphoblastoid cell lines and pathological specimens.

Cell Line↗
PubMedDate not supplied

Serial transplantation and characterization of a canine diffuse large cell lymphoma grafted in nude mice.

A continuous canine lymphoma cell line (DL. 24N) was established by serial transplantation from a diffuse large cell lymphoma into athymic nude mice, yielding subcutaneous tumours at the injection site associated with lymph node metastasis. The transplanted tumour cells, of canine origin as assessed by the karyotype, appear comparable to the large non-cleaved and immunoblastic human cells, as did the initial tumour cells. Immunological studies show reactivity with antibodies to dog immunoglobulins, DT-2 and Thy-1, to MHC-class II antigens, and to both CD10 (CALLA) and CD21 (CR2) human antigens. Such a cell line, showing similarities with some of the human diffuse large cell lymphomas, will thus provide a new tool for further comparative studies of malignant lymphomas.

Animals↗