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Biomedical subjects

Z Layrisse

Publications and source records attributed to Z Layrisse.

At least 55 records · Page 3Linked to original sources
PubMed1987

Sharing of MHC haplotypes among apparently unrelated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

From the study of HLA, complement, and glyoxalase I alleles in 82 Venezuelan individuals belonging to 19 families of mixed ethnic origin having 20 affected newborns with salt-wasting congenital adrenal hyperplasia due to 21-hydroxylase (21-OH) deficiency, a total of 38 disease haplotypes and 53 nondisease haplotypes were found. Of the pathological haplotypes 47% were found to share the HLA-B39 or -Bw62 specificities, 55% of them in combination with the BFS, C2C, C4A4, C4B2 (SC42) complotype. The frequencies of HLA-B39 and -Bw62 among the affected haplotypes were 29 and 18% as compared with 6 and 0% among the nondisease haplotypes of the same families. Statistical associations (P less than 0.01) with salt-wasting adrenal hyperplasia were found with the SC42 complotype and with the combination SC42, HLA-B39. These results are markedly different from those reported in the literature which show an "association" at the population level among many Caucasoid samples of HLA-Bw47 and the extended haplotype (HLA-Bw47, DR7,FC91,0) with the salt-wasting form of the disease. Furthermore, four of the unrelated patients reported here were homozygous for all the major histocompatibility complex loci tested, while three others were homozygous for at least two HLA loci. Analysis of the geographical origin of the grandparents indicated clustering of the deficiency carrier HLA haplotypes. This observation, together with the fact that there is an excess of homozygotes among the patients in Venezuela, strongly suggests that salt-wasting 21-OH deficiency congenital adrenal hyperplasia is mostly the result of a founder effect of relatively hyperplasia is mostly the result of a founder effect identity by descent of a few abnormal alleles at the 21-OHB locus in most cases. The mutation marked by HLA-Bw47 was not observed in this population.

Adrenal Hyperplasia, Congenital↗
PubMed1986

Chediak-Higashi syndrome: immunological responses to Epstein-Barr virus studies in gene heterozygotes.

Immunologic studies were performed in five fathers and nine mothers of patients with Chediak-Higashi Syndrome (CHS). Antibody response to Epstein-Barr virus capsid antigen was higher than in normal controls. Antibodies to diffuse component of the early antigen were not detected and serum antibodies to the restricted component of the early antigen were observed in 64% of the subjects studied. Low natural killer activity and increased proportions of OKT8 positive cells were increased. These data indicate that immunologic alterations similar to those seen in CHS patients can be observed in their asymptomatic parents.

Antibodies, Viral↗
PubMed1986

Immunoregulatory alterations in Plasmodium falciparum and Plasmodium vivax infections.

Studies on the immune function of patients with acute Plasmodium vivax or P. falciparum infections were performed. All subjects were residing in recent malaria endemic areas of Venezuela. Lymphopenia, reduction of peripheral blood T-lymphocytes positive for monoclonal antibody OKT4 (T helper) a decrease of in vitro mitogenic proliferative response and natural killer cell activity were observed. Serum lymphocytotoxic antibodies reactive at 37 degrees C were detected in both groups of patients as well as serum autoantibodies. The possible role of lymphocytotoxic autoantibodies in the etiology of the T-lymphocyte depletion and acquired immunological perturbations in human malaria is discussed.

Antilymphocyte Serum↗
PubMed1985

Definition of DW8.2 by primary and secondary mixed lymphocyte cultures.

Using HLA-DW8 homozygous typing cells (HTC) of different ethnic origin it is possible to identify three subgroups of the DW8/DRW8 product (Mickelson et al., 1983). To further characterize the DW8.2 subgroup defined by HTCs of Amerindian origin we have now generated bulk PLTs within members of one extended Amerindian family and within selected HTCs of Caucasian, Oriental, and Amerindian origin. A panel of 61 DRW8 positive and negative donors of the three ethnic groups was used to test 15 different PLTs. Our results demonstrate that it is possible to generate DW8.1, 8.2, or 8.3 sensitized lymphocytes which distinguish in secondary cultures between each of the three subgroups of the DW8/DRW8 products. Of 40 DRW8 cells tested, 100% Caucasians typed as DW8.1, 100% Amerindians were 8.2; 75% Orientals were DW8.3; 8.3% were DW8.2, and 16.6% could not be classified within any of these subgroups. DRW8 individuals of mixed ethnic origin typed as either DW8.1 or DW8.2 and one DRW8 homozygous donor behaved as heterozygous 8.1/8.2. These results confirm the subdivision of the DW8/DRW8 product and explain the poor correlation and unexpected responses reported in MLC with DW8 HTCs and DRW8 donors of different ethnic origin.

Asian People↗
PubMed1985

HLA antigens in hemophiliacs A with or without factor VIII antibodies in a Venezuelan Mestizo population.

Twenty-eight unrelated hemophilia A patients, seven of them with anti-factor VIII antibodies were typed for HLA-A, B, C antigens and 25 of them for HLA-DR. The results show a significant difference in HLA-DR4 frequency between hemophiliacs with antibodies who lack this antigen and hemophiliacs without antibodies, in whom HLA-DR4 is increased as compared to a healthy control series. This data suggests that DR4 may be associated with a factor preventing anti-factor VIII immunization.

Antibodies↗
PubMed1984

A study of HLA-DR2 associated HLA-Dw/LD specificities.

HLA-Dw2 and Dw12 are both associated with HLA-DR2; however, these specificities accounts for only 86% (161/188) of the DR2+ haplotypes in our North American Caucasian panel. In an attempt to identify new DR2 associated antigenic clusters, we have generated four primed lymphocyte (LD) typing (PLT) reagents in haploidentical familial combination against DR2+ Dw blank haplotypes. These reagents were positively restimulated by 11 of 16 DR2+ Dw blank cells tested, with good discrimination from Dw2 and Dw12+ cells, thus identifying a new antigenic cluster provisionally termed LD-MN2. We have compared the LD-MN2 specificity with the specificity LD-5a defined by two DR2+ HTCs, BAS and REM, (Layrisse, Caracas) which have been included in the pre-1984 Workshop Cluster DB9. Although none of our DR2+ cells gave typing responses to these two HTCs defining LD-5a, PLT studies did indicate an interrelationship between these specificities and with the specificity tb24 defined with the HTC, FJO (Betuel). The LD-5a HTCs, four LD-5a heterozygous cells, and two additional HTCs (WJR-Hansen, Seattle and FJO/tb24--Betuel, Lyon) significantly restimulated the anti-MN2 PLT reagents, though usually not as strongly as the MN2+ cells. MN2+ cells primed against the LD-5a HTCs were restimulated by only the LD-5a+ cells. Dw2+ cells primed against FJO were restimulated by some, but not all MN2+ cells. These results suggest that MN2, tb24, and LD-5a share some determinants, not shared with most cells which type as Dw2 and Dw12, though differing by other stimulatory determinants. These studies emphasize the necessity of studying new antigenic clusters by both PLT and HTC methodologies as well as testing different ethnic groups.

Epitopes↗
PubMed1984

Cytotoxic antibodies in sera of Venezuelan multiparous women of Amerindian and mixed ethnic origin.

Sera from 464 multiparous women of mixed ethnic origin and 114 Amerindian mothers (Warao of Western Venezuela), were studied for lymphocytotoxicity using a panel of B and T lymphocytes isolated from 50 to 100 individuals from the same populations. Twenty-five and 9.65% of the sera, respectively, showed activity against at least 5% of the panel. Among the women of mixed ethnic origin 10% produced antibodies directed against one or more HLA Class I antigens while 2 sera contained monospecific anti-DR antibodies; among the Warao, only 2 sera recognized HLA antigens: a Bw51 and an undetermined Cw antigen which shows linkage disequilibrium with Bw16 in both populations.

Adult↗
PubMed1983

Analysis of the HLA-DRw8 haplotype: recognition by HTC typing of three distinct antigen complexes in Caucasians, Native Americans, and Orientals.

We have used seven HLA-D homozygous typing cells (HTC) in a comparative study of the DRw8 antigen complex in three racial groups. Three distinct HLA-D specificities were recognized, each associated with HLA-DRw8. Four of the HTC defined a DRw8-associated HLA-D specificity designated 8.1, one defined a specificity designated 8.2, and two defined a specificity designated 8.3. Each of the three specificities showed an association with a distinct racial group: Dw"8.1" in Caucasians, Dw"8.2" in Pacific Northwest Indians, and Dw"8.3" in Orientals. An informative primed lymphocyte (PLT) cell generated against a Dw"8.1" haplotype was able to distinguish 8.1 from 8.2 and 8.3. Using selected anti-DRw8 sera, a serologic distinction between 8.1 and 8.3 could also be made. It was thus possible, by using both cellular and serologic techniques in a comparative population study, to recognize at least three HLA-D-defined splits of the DRw8 haplotype.

Asian People↗
PubMed1983

Family studies of the HLA system in acute post-streptococcal glomerulonephritis.

Eighteen families (67 siblings) of index cases with acute post-streptococcal glomerulonephritis (APSGN) were typed for HLA-A,B,C,DR antigens. Twenty cases of clinical nephritis and 10 cases of asymptomatic disease with detected among the sibships. In eight families with more than one affected individual comprising 18 sib pairs random segregation of paternal and maternal HLA haplotypes was found (0.5 less than p less than 0.06), but some antigens (CW1, DR3) showed deviation from the expected 1:1 ratio in affected and nonaffected siblings in backcross families. We had previously noticed the existence of Mendelian recessive ratios in APSGN but in the absence of clear evidence for a dominant or recessive mode of inheritance for a putative APSGN susceptibility gene(s), pedigree data were analyzed twice for linkage with HLA using the two genetic models. The data obtained, although not sufficient to reject the hypothesis of linkage, provide no support for it. Comparison of the frequency of 61 HLA antigens among 42 unrelated APSGN patients and 109 controls, showed that HLA-DRW4 is more frequent among the former (pc = 0.0500).

Acute Disease↗
PubMed1982

HLA-D typing with homozygous cells identified in an American indigenous isolate. II. Family studies and D/DR relationship.

Twelve American Indian nuclear families with 2-5 siblings have been HLA-D typed using mixed lymphocyte cultures and clusters of homozygous typing cells (HTC) of Caucasoid origin to detect DW1-DW7 and typing cells of American Indian origin to detect LD5A, LD15A and LD15B antigens. Results obtained demonstrate complete absence of DW1-DW7 in these families and illustrate the inheritance and segregation of LD5A, LD15A and LD15B. DR typing results obtained with the 8th International Histocompatibility Workshop genetic set of antisera indicate inheritance in coupling of DR2 with LD5A, of DR6.2 (DR3+6, MT1 negative, MT2 positive) with LD15A, and of DRW8 with LD15B. The existence of MLC activating antigen(s) different to DW4, yet associated to DRW4 in this population is postulated. The D/DR relationship present in this American Indian isolate demonstrate once more that DR2 can be inherited in combination with an HLA-D antigen different to DW2, and that LD15A HTC define a second sub-cluster of the broad DW6 specificity group, which is inherited with DRW6.2 and BW62 antigens in the Warao population.

Family↗
PubMed1980

Restriction and persistence of polymorphisms of HLA and other blood genetic traits in the Parakanã Indians of Brazil.

Results concerning HLA types and 22 other blood genetic systems are reported for the Parakanã Indians of northern Brazil, a tribe that is notable for the light color and pilosity of some of its members. No clear evidence of Caucasoid admixture was found, but the Parakanã show unusual frequencies in the EsD1, PGM1(1) Gc2, CpB, Fya, Dia, and LM genetic markers. In addition, the very rare Rh allele ry is present, as well as what seems to be a new PGM2 variant. There is very limited heterogeneity in the HLA system. All these distinctive features may have arisen through a combination of founder effects and genetic drift. However, low FIS values, as well as higher mean ages in heterozygous as compared to homozygous persons, suggest that an heterotic effect is counteracting these dispersive forces.

Adolescent↗
PubMed1979

Hepatitis--Bs antigen in an isolated Indian population of southern Venezuela: a family study.

A genetic analysis of the presence of HBsAg in a population of which 7.2% of the members were positive is presented. Though the ratios of carriers: non-carriers were generally in good agreement with expectation if the carrier state were determined by homozygosity for a single recessive gene, the two examples of mating most critical to a test of the hypothesis, carrier X carrier, yielded 2 normal children among 4 in one family, and one normal child, the only offspring, in the second family. Other investigators have reported similar findings. We conclude that the hypothesis of simple recessive inheritance cannot be sustained.

Adolescent↗
PubMed1978

HLA--D typing with homozygous cells identified in an American indigenous isolate. I. Population studies.

Lymphocytes from six individuals homozygous for their HLA--A, --B, --C and --D loci belonging to an American indigenous group, the Warao, have been used as typing cells to detect HLA--D determinants in 121 donors from the same indigenous isolate and in 71 donors of mixed ethnic origin living in Venezuela. Two determinants responsible for strong proliferation in mixed lymphocyte cultures have thus been identified. Four HLA--A2, B5 cells (r values between 0l72 and 0.57) identify a determinant provisionally called LD5a showing a gene frequency of 0.30 among the Warao and of 0.09 among the population of mixed ethnic origin. The nearest B locus antigen to this new specificity among the Warao is HLA--B5 (r value = 0.20). A second determinant identified by two HLA--A2, B15 sisters (r values of 0.71) shows a gene frequency of 0.15 among the Warao and of 0.03 among the mixed population. The latter is related to Dw8 as shown by results of the VI and VII Histocompatibility Workshops, and is weakly associated (r value of 0.28) to HLA--B15 among the American indigenous population tested.

Epitopes↗