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C Navarrete

Publications and source records attributed to C Navarrete.

At least 73 records · Page 4Linked to original sources
PubMed1987

Cytogenetic study in children chronically habituated to inhalation of volatile substances.

Deliberate inhalation of volatile substances is a common and harmful phenomenon among young persons around the world. Clinical and cytogenetic studies were performed in 35 children (33 boys and 2 girls) chronically habituated to inhalation of volatile agents, with the aim to define whether this practice is associated with chromosome abnormalities and if so to what extent. A significant increase in the rate of chromosome abnormalities and in the frequency of sister chromatid exchanges (SCE) was found in sniffers over the values in controls (p less than 0.001). Clinical, socioeconomic, and cytogenetic findings are discussed.

Adolescent↗
PubMed1987

Frequency and associations of HLA-DR and HLA-DQ antigens in a British Caucasoid panel.

The frequencies of the HLA-DR and -DQ antigens, including those of the new specificities "DRBr" and TA10, were established in a random panel of 286 British Caucasoids. The most frequent DR antigens were DR2, DR4 and DR7. The DR-DQ antigen associations were examined and the only heterogeneity found was with DR7 which was found to be associated predominantly with DQw2 but also with DQw3. The DR4's were subdivided into those positive and those negative for TA10 and DR4-TA10 was found to be associated with HLA-B44.

Gene Frequency↗
PubMed1986

Separate ontogeny of two macrophage-like accessory cell populations in the human fetus.

Human macrophage-like accessory cells were analyzed as they emerge in the absence of extrinsic antigens during fetal development. Monoclonal antibodies to monocytes/macrophages were used in combination with antibodies to HLA class II molecules. In the yolk sac and mesenchyme sampled at wk 4 to 6 of fertilization age, cells with dendritic morphology formed two populations distinguishable by phenotypic criteria: type i (majority) carried both macrophage-associated (RFD7+) and monocyte-associated markers (UCHM1+) but no detectable HLA-DR antigen, and type ii (minority) constitutively expressed class II (HLA-DR and -DP) but no RFD7 and UCHM1. The emergence of this heterogeneity preceded the formation of both thymus and bone marrow. During additional development, type i and type ii cells seeded to different microenvironments and underwent some additional phenotypic changes. Cells of type i, the RFD7+ population with high lysosomal (acid phosphatase) activity, were seen in the thymic cortex, marginal zone of lymph nodes, splenic red pulp, and in the midst of erythropoietic activity within the bone marrow. These cells were UCHM1- and class II-. Cells of type ii formed the population of HLA-DR+, RFD7- interdigitating cells, early inhabitants of T cell areas in the developing thymic medulla, lymph nodes, spleen, and tonsil. The Type ii cells that had already settled in their nichès expressed not only HLA-DR and -DP but also HLA-DQ, and another class II antigen identified by the antibody RFD1, which shows the restricted tissue distribution of HLA-DQ, but is governed by genes that are outside of and telomeric to the HLA-DQ region (or HLA-DR). Finally, subpopulations of macrophages (RFD7+, acid phosphatase-positive) in the fetal gastrointestinal and hepatic systems were HLA-DR+; the latter appear to include precursors of Kupffer cells in the developing liver.

Acid Phosphatase↗
PubMed1986

Ontogenic and functional implications of the differential expression of HLA-DQ antigens on leukemic cells.

We have examined the HLA class II antigenic profiles on different types of leukemic cells and have attempted to relate these findings to the normal differentiation pathways of the cells from which they have arisen. Monoclonal antibodies reacting with the different HLA class II determinants, HLA-DR, DRw52(MT), and DQ, were used to study the expression of these antigens on Epstein-Barr virus transformed cell lines, chronic lymphocytic leukemic cells, acute lymphoblastic leukemic blasts, acute myeloblastic leukemic blasts, and established leukemic cell lines by indirect immunofluorescence binding and immunoprecipitations. The results showed that whereas the HLA-DR and HLA-DRw52(MT2) antigens are normally expressed on the majority of the cells tested, there is a different expression of the HLA-DQ antigens on acute leukemic blasts, chronic lymphocytic leukemic cells, and leukemic cell lines indicating that the DQ molecules may be differentiation antigens preferentially expressed on mature cells. Furthermore, when the pre-B cell leukemic line NALM 6 was induced to differentiate with phorbol ester (TPA), normal expression of the HLA-DQ antigen was obtained after 5 days of culture. The absence of HLA-DQ antigens from the acute leukemic blasts suggests that these immature cells "froze" in the early stages of cell differentiation. We discuss these findings in relation to the role of these HLA class II antigens in cell differentiation and the immune response.

Antibodies, Monoclonal↗
PubMed1986

HLA-Dw specificity assignments are independent of HLA-DQ, HLA-DR, and other class II specificities and define a biologically important segregant series which strongly activates a functionally distinct T cell subset.

Several lines of evidence indicate that HLA-Dw, as defined by HTC typing, is not the result of the combined stimulatory effect of HLA-DR and DQ. Therefore, responder cells do not have to share HLA-DQ antigens with the stimulator HTCs to give a typing response. The common HLA-DR-DQ associations observed in HTCs correspond to different patterns of linkage disequilibrium in different populations. HLA-DQ and HLA-Dw are functionally heterogeneous. Although HLA-DQ molecules may play a role in primary stimulation, this role is distinct from that of Dw determinants which have strong lymphocyte activating properties. The role of the HLA-DQ determinants on the other hand, is one of modulating the total T cell response by controlling the proliferation of suppressor and cytotoxic cells. The primary MLC response is the result of the proliferative effect of HLA-Dw, DR, DP, and other associated determinants, in conjunction with a modulatory effect of DQ molecules. However, HLA-Dw (as detected by HTC typing) are DR associated determinants which are immunodominant in primary MLR. The genes of the HLA-DR subregion have been named DR by the WHO nomenclature committee. This subregion encodes the HLA-DR specificities and the DRw52 and DRw53 determinants. Unfortunately this nomenclature does not take into account the need to define the genetic basis of the HLA-Dw determinants--whether they are encoded by separate genes within the HLA-DR subregion or whether they are encoded by as yet unspecified genes in the HLA class II region in linkage disequilibrium with HLA-DR DRw52/53. There are at least three and possibly four beta chain genes in the HLA-DR subregion, all in strong linkage disequilibrium with each other. Some of these are expressed in most haplotypes while others are not; some behave as pseudogenes in some haplotypes and in others, all the genes are expressed. All the genes of the class II region have not been fully characterized. HLA-Dw determinants may be specified by one or more of these genes. When more information becomes available, the genetic and molecular basis of the HLA-Dw series as well as the functional heterogeneity and antigenic strength of the various class II determinants will be better understood.

Epitopes↗
PubMed1986

Different HLA associated gene combinations contribute to susceptibility for coeliac disease and dermatitis herpetiformis.

Forty two white patients of British or Irish descent with coeliac disease and 28 with dermatitis herpetiformis were typed for class I HLA-A, B, and C, and class II DR and DQ antigens. In coeliac disease there was a significant increase in the frequencies of A1, B8, DR3, DR7, and DQw2 compared with controls but no increase of DR2. In dermatitis herpetiformis there were similarly increased frequencies of A1, B8, DR3, and DQw2. In contrast with coeliac disease, however, the frequency of DR7 (18%) was no different from the control group but there was an increased frequency of DR2.

Adolescent↗
PubMed1986

Clinical, genetic and cytogenetic studies in couples attending an infertility clinic.

The present study was carried out in order to assess the genetic component in a group of sterile or infertile couples from a latin american population. During a six-year-period, 258 patients were investigated. Sixty two per cent of the cases were studied for sterility and 38% for infertility. It was found that 34% had genetic pathology. In infertile couples the frequency of chromosome abnormalities was 2.8%; when sterility was also considered this frequency was 11.6%. Chromosome variants were found in 11.4% of the sterile patients and in 8.8% of the infertile cases.

Chromosome Aberrations↗
PubMed1985

Different functions and associations of HLA-DR and HLA-DQ(DC) antigens shown by serological, cellular and DNA assays.

Two consanguineous Caucasoid HTCs, DHI and FPA, were investigated, the latter having an unusual HLA-DR/DQ(DC) association. Both these HTCs typed clearly as HLA-DRw11. However, while DHI typed as DRw11/DQw3(DC4) as expected, FPA typed as DRw11/DQw1(DC1) instead. Although extremely rare in Caucasoids, DRw11/DQw1 is a common pattern of association in Nigerian Negroids. Southern blots of DNA extracted from EBV cell line derived from FPA, hybridized with HLA-DC alpha and HLA-DC beta probes, confirmed this unusual DRw11/DQw1(DC1) association. In addition the DC alpha probe showed a unique additional restriction fragment length polymorphism (8 kb) attributable to the DX gene in the FPA DNA. When DHI and FPA were used as stimulators in MLC, the patterns to typing responses obtained were not completely concordant although they overlap to some extent. For this reason FPA has been locally designated Dw'F5', distinct from Dw5. Furthermore, the HLA-DQ antigens of the responder cells were not necessarily the same as those of the HTCS to which they gave typing responses (FPA and DHI). Functional studies using these two HTCs showed that the DQ(DC) antigens probably have no direct lymphocyte activating properties but rather have a regulatory role in controlling responses to allodeterminants in MLC.

Antibodies, Monoclonal↗
PubMed1985

HLA polymorphisms in Nigerians.

The HLA class I and class II phenotypes of a panel of 114 unrelated Nigerians have been determined. The panel was tested for all the known class I antigens and comparisons of the HLA-A and -B frequencies with those of other African Negroid populations revealed some differences. Only limited comparisons could be made for the HLA-DR and -D frequencies as these are not available for any well-defined African Negroid population. The data concerning the class II antigens of this panel are the most interesting. Half of the DRw11-positive panel members are DQw3 negative and DQw1 positive. In addition, there is dissociation of some HLA-D and -DR specificities, a number of panel members are positive for an HLA-D specificity and are negative for the corresponding HLA-DR specificity. Our results show the value of population studies in the investigation of the relationship between the different HLA class II antigens.

Black People↗
PubMed1985

Differential expression of HLA-DR and HLA-DQ antigens on normal cells of the myelomonocytic lineage.

We have previously shown that HLA-class II antigens have a differential expression on acute myeloblastic leukaemia (AML) blasts. These cells express HLA-DR molecules but the HLA-DQ antigens are undetectable. In this paper we study the expression of HLA-DR and HLA-DQ antigens, using monoclonal antibodies (MoAbs), on normal cells of the myelomonocytic lineage: the common myelomonocytic progenitor (CFU-GM) and the monocytes, by techniques of inhibition of CFU-GM growth and double immunofluoroscence, respectively. The results show that HLA-DR and HLA-DQ antigens are differentially expressed on normal myelomonocytic cells. While HLA-DR molecules are expressed on CFU-GM and on the majority of peripheral blood monocytes, HLA-DQ antigens are not expressed on CFU-GM and only present on a subpopulation of monocytes. This data further confirms that HLA-DR and HLA-DQ molecules are coded by different genes with independent regulation of the gene expression not only on myeloid leukaemias but also on normal cells of the myelomonocytic lineage.

Adult↗
PubMed1983

Differential expression of HLA-DR and DR-linked determinants on human leukemias and lymphoid cells.

Leukemic and normal hemopoietic cells were examined with the monoclonal anti-bodies DA2 and Genox 353 for the presence of HLA-DR and DR-linked (DC/MB) determinants, respectively. Although most non-T acute leukemias and leukemic cell lines expressed the monomorphic DR determinant detected by DA2, fewer than expected expressed the DR-linked polymorphic specificity detected by Genox 353. TdT+ lymphoid precursors from normal bone marrow were also DA2+ but Genox 353-. T cells and thymocytes which were DA2-, Genox 353- became DA2+, Genox 353+ after activation in vitro. Immunoprecipitation using DA2 and Genox 353 gave bands on polyacrylamide gel-electrophoresis which were of different molecular weights. In addition, DA2 could absorb out Genox 353 determinants from a cell lysate whereas Genox 353 could not absorb out DA2 determinants. It is concluded that DA2 and Genox 353 detect HLA-DR and DR-linked (DC1/MB1) determinants, respectively, and that these are differentially expressed on hemopoietic cells during differentiation.

Antibodies, Monoclonal↗
PubMed1980

Precursor and effector phenotypes of activated human T lymphocytes.

In mice, thymus-derived lymphocytes are differentiated into functional subclasses by their cell surface antigens. The Ly 1 determinants are present on T cells with a helper function, whereas Ly 2 and Ly 3 antigens are expressed on the surface of lymphocytes with suppressor or cytotoxic functions. In man also, T-cell subsets have been identified using allo- and heteroimmune sera and, more recently, using monoclonal antibodies, which seem to identify helper and suppressor or cytotoxic subpopulations. The major histocompatibility system (MHS)-encoded Ia antigens belong to several polymorphic families of membrane associated glycoproteins originally found on B lymphocytes; however, they have also been shown to be markers for suppressor T cells in mice. Recent studies have shown that in both mouse and man, T cells activated by a mixed lymphocyte reaction or by mitogens become Ia+. Furthermore, some human T lymphoid cells, either freshly isolated from peripheral blood or after in vitro activation by lectins or alloantigens, possess suppressor properties. We report here the phenotype of a T suppressor-cell subpopulation which was induced in long-term culture of lymphoid cells after activation with phytohaemagglutinin (PHA). Our results suggest that a subset of T cells was progressively expanded over a period of 8 days in culture and that, with the expression on the surface of these cells of 'Ia-like' antigens, they acquired the capacity to suppress the proliferative response of syngeneic or allogeneic lymphocytes to alloantigens or mitogens.

Antigens, Surface↗
PubMedDate not supplied

Chromosome abnormalities and sister chromatid exchanges in children with acute intoxication due to inhalation of volatile substances.

Deliberate inhalation of volatile substances is a common and harmful practice among young persons worldwide. Recently, we described chromosome damage in children who chronically inhale volatile agents. Clinical and cytogenetic studies were performed for 15 "sniffing" children (13 boys and 2 girls), the purpose of which was to define the chromosomal effect of the acute intoxication. A significant increase in the rate of chromosome abnormalities and in the frequency of sister chromatid exchanges (SCEs) was found in sniffers vs. controls. The values were also higher in children who were acutely intoxicated than in those who chronically inhaled volatile agents. Clinical, socioeconomic, and cytogenetic findings are also discussed.

Adolescent↗
PubMedDate not supplied

HLA class I and class II antigen associations in acute leukaemias.

HLA-A,B,C and DR antigen frequencies were determined in a group of 188 patients suffering from acute myeloid (AML) and acute lymphoid leukaemia (ALL). These antigen frequencies were compared with those obtained on a panel of normal individuals (n = 109) of the same ethnic origin. The significance of the differences in the antigen distribution and the strength of the associations between particular HLA antigens and the disease were then calculated. The results obtained show a decreased frequency of HLA-Aw19 in the overall group of patients and the group of patients with ALL. In addition, the antigen frequency of the HLA-B18 and DR5(DRw11) antigens was also decreased in the overall group of patients and in those patients with AML but not in the patients with ALL. The results suggest that the antigen Aw19 may confer some degree of resistance to the development of ALL and that the HLA-B18 and/or DR5 antigens may be resistance factors for the development of AML.

Adolescent↗
PubMedDate not supplied

Modulation of the expression of HLA class II antigens by gamma interferon and phorbol ester TPA on myeloid leukaemic cell lines.

We investigated the effect of gamma interferon and phorbol ester (TPA), on the expression of HLA class II molecules of myeloid leukaemic cell lines K562, U937, KG-1, HL-60 and ML-2. Gamma interferon induced the expression of HLA-DR but not HLA-DQ on HL-60 and ML-2, increased the expression of HLA-DR and DQ on U937 and induced the expression of HLA-DQ on KG-1. TPA treatment did not affect the expression of HLA class II antigens on U937 and KG-1 and induced the expression of HLA-DR and HLA-DQ on HL-60 and ML-2. TPA treatment did not affect the HLA phenotype of K562 but gamma interferon did induce HLA class I molecules. Thus, gamma interferon cannot only increase the expression of HLA products already expressed on the cells but can also induce the de novo synthesis of these molecules on myeloid leukaemic cell lines.

Cell Line↗