Dose-dependent hyporreactivity to phytohemagglutinin in systemic lupus erythematosus

The response of peripheral blood lymphocytes to stimulation with optimal and suboptimal doses of PHA was measured in patients with active SLE before initiation of therapy. The [³H]thymidine uptake of SLE patient's lymphocytes was significantly lower than that of their matched controls when cells were stimulated with suboptimal PHA doses in the presence of autologous plasma. A moderate improvement in the PHA response was observed by culturing washed patient's lymphocytes in medium supplemented with pooled normal human plasma, but only in one case the response reverted to normal values. A significant inhibitory effect of SLE plasma on the response of normal donor's lymphocytes to stimulation with low PHA doses, which was independent from the presence of lymphocytotoxic antibodies and persisted after complement inactivation was observed in further experiments.The results indicate that depression of lymphocyte transformation could be demonstrated in patients with active SLE using suboptimal doses of PHA and suggest that this depression may be caused by both a defect in the responding lymphocyte populalation and the presence of inhibitory factor(s) in SLE plasma.     

Reconstructing the Population Genetic History of the Caribbean

The Caribbean basin is home to some of the most complex interactions in recent history among previously diverged human populations. Here, we investigate the population genetic history of this region by characterizing patterns of genome-wide variation among 330 individuals from three of the Greater Antilles (Cuba, Puerto Rico, Hispaniola), two mainland (Honduras, Colombia), and three Native South American (Yukpa, Bari, and Warao) populations. We combine these data with a unique database of genomic variation in over 3,000 individuals from diverse European, African, and Native American populations. We use local ancestry inference and tract length distributions to test different demographic scenarios for the pre- and post-colonial history of the region. We develop a novel ancestry-specific PCA (ASPCA) method to reconstruct the sub-continental origin of Native American, European, and African haplotypes from admixed genomes. We find that the most likely source of the indigenous ancestry in Caribbean islanders is a Native South American component shared among inland Amazonian tribes, Central America, and the Yucatan peninsula, suggesting extensive gene flow across the Caribbean in pre-Columbian times. We find evidence of two pulses of African migration. The first pulse—which today is reflected by shorter, older ancestry tracts—consists of a genetic component more similar to coastal West African regions involved in early stages of the trans-Atlantic slave trade. The second pulse—reflected by longer, younger tracts—is more similar to present-day West-Central African populations, supporting historical records of later transatlantic deportation. Surprisingly, we also identify a Latino-specific European component that has significantly diverged from its parental Iberian source populations, presumably as a result of small European founder population size. We demonstrate that the ancestral components in admixed genomes can be traced back to distinct sub-continental source populations with far greater resolution than previously thought, even when limited pre-Columbian Caribbean haplotypes have survived.     

High KIR diversity in Amerindians is maintained using few gene-content haplotypes

Interaction between killer cell immunoglobulin-like receptors (KIR) and cognate HLA class I ligands influences the innate and adaptive immune response to infection. The KIR family varies in gene content and allelic polymorphism, thereby, distinguishing individuals and populations. KIR gene content was determined for 230 individuals from three Amerindian tribes from Venezuela: the Yucpa, Bari and Warao. Gene-content haplotypes could be assigned to 212 individuals (92%) because only five different haplotypes were present—group A and four group B. Six different haplotype combinations accounted for >80% of individuals. Each tribe has distinctive genotype frequencies. Despite few haplotypes, all 14 KIR genes are at high frequency in the three tribes, with the exception of 2DS3. Each population has an even frequency of group A and B haplotypes. Allele-level analysis of 3DL1/S1 distinguished five group A haplotypes and six group B haplotypes. The high frequency and divergence of the KIR haplotypes in the Amerindian tribes provide greater KIR diversity than is present in many larger populations. An extreme case being the Yucpa, for whom two gene-content haplotypes account for >90% of the population. These comprise the group A haplotype and a group B haplotype containing all the KIR genes, except 2DS3, that typify the group B haplotypes. Here is clear evidence for balancing selection on the KIR system and the biological importance of both A and B haplotypes for the survival of human populations.Electronic Supplementary Material Supplementary material is available for this article at     

Generation of the HLA-B35, -B5, -B16, and B15 groups of alleles studied by intron 1 and 2 sequence analysis

 HLA-B is the most polymorphic of the major histocompatibility complex classical class I loci. This polymorphism is mainly in exons 2 and 3, which code for the molecule’s α1 and α2 domains and include the antigenic peptide binding site. Recent studies have indicated that not only exons but also the intron 2 region may be involved in the generation of certain HLA-B alleles such as B ^* 3906 and B ^* 1522. To study the degree of intron 2 participation and the mechanisms that generate polymorphism at the HLA-B locus, intron 1 and 2 sequences from the HLA-B35, -B5, -B16 and -B15 groups of alleles were obtained. A group-specific intronic polymorphism was found: namely, B ^* 5301 shows intron 1 and 2 sequences identical to those found in all B35 alleles studied. On the other hand, B ^* 5101 and B ^* 52012 show the same intron 1 and 2 sequences and their intron 1 is the same as that found in the B35 group. This suggests that B5 and B35 groups of alleles may have arisen from a common ancestor. All known B16 alleles show the same introns 1 and 2, with the exception of B ^* 39061 and B ^* 39062, and all B15 alleles also bear the same introns 1 and 2, with the exception of B ^* 1522. Variability at intron 1 is more restricted than at intron 2, and the use of intron 1 for HLA-B allele phylogenetic analysis is better for grouping alleles of a postulated common origin. In conclusion, there is a remarkable conservation of intronic sequences within related HLA-B alleles, which probably reflects a common origin and perhaps a selective force avoiding DNA changes. Intronic sequences are also potentially useful to design DNA typing strategies. Received: 11 March 1997 / Revised: 29 May 1997     

Alleles at four HLA class II loci determined by oligonucleotide hybridization and their associations in five ethnic groups

The use of polymerase chain reaction (PCR) and oligonucleotide hybridization offers a new approach for the definition of HLA class II alleles. It has been possible to determine 43 alleles of DRB1, four of DRB3, two of DRB4, four of DRB5, eight of DQA1, and 14 of DQB1. These alleles are inherited together in members of families and form closely associated groups which are found repeatedly and in characteristics patterns in different populations. We have determined the HLA class II alleles and analyzed their association in 431 healthy unrelated subjects including 161 North American Caucasians, 53 Latin Americans, 61 Blacks, 88 Chinese, and 68 Israeli Jews. For-locus haplotypes (DRB1; DRB3/4/5; DQA1; DQB1) were derived from 79 B cell lines and the analysis of segregation in 34 nuclear families. The B-cell lines yielded 37 and the families showed the same, and 20 other, haplotypic combinations. In addition to these 57 haplotypes, associated alleles were assigned in the unrelated panels following certain rules. The resulting haplotypes were assigned to groups known to share associated alleles. The groups were: (1) DR1, DR2, and DRw10 (13 haplotypes); (2) DR3 and DRw6 (26 haplotypes); (3) DR5 and DRw8 (24 haplotypes); (4) DR4, DR7, and DR9 (24 haplotypes). Their distribution in populations with different ethnic backgrounds was analyzed. The expressed DRB4 allele and its null mutant were determined by PCR and oligonucleotide hybridization. The different DR7 haplotypes resulting from these determinations were analyzed in a panel of 130 North American Caucasoids. This comprehensive analysis of class II HLA haplotypes in human populations should be useful in understanding the role of these genes and in various applications including anthropolgy, disease susceptibility, and transplantation of allogeneic organs and tissues. Address correspondence and offprint requests to: P. Stastny     

Y-chromosome evidence for differing ancient demographic histories in the Americas

To scrutinize the male ancestry of extant Native American populations, we examined eight biallelic and six microsatellite polymorphisms from the nonrecombining portion of the Y chromosome, in 438 individuals from 24 Native American populations (1 Na Dené and 23 South Amerinds) and in 404 Mongolians. One of the biallelic markers typed is a recently identified mutation (M242) characterizing a novel founder Native American haplogroup. The distribution, relatedness, and diversity of Y lineages in Native Americans indicate a differentiated male ancestry for populations from North and South America, strongly supporting a diverse demographic history for populations from these areas. These data are consistent with the occurrence of two major male migrations from southern/central Siberia to the Americas (with the second migration being restricted to North America) and a shared ancestry in central Asia for some of the initial migrants to Europe and the Americas. The microsatellite diversity and distribution of a Y lineage specific to South America (Q-M19) indicates that certain Amerind populations have been isolated since the initial colonization of the region, suggesting an early onset for tribalization of Native Americans. Age estimates based on Y-chromosome microsatellite diversity place the initial settlement of the American continent at approximately 14,000 years ago, in relative agreement with the age of well-established archaeological evidence.     

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 Parkanã show unusual frequencies in the EsD¹, PGM¹₁, Gc², Cp^B, Fy^a, Di^a, and L^M genetic markers. In addition, the very rare Rh allele r^y 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 F_is values, as well as higher mean ages in heterozygous as compared to homozygous persons, suggest that an heterotic effect is counteracting these dispersive forces.     

Synthesis and characterization of platinum-sterol hydrazone complexes with biological activity against Leishmania (L.) mexicana

Leishmaniasis is a parasitic zoonosis caused by protozoans of the genus Leishmania transmitted by insects known as phlebotomines, which are found in wild or urban environments. The disease occurs in tropical and sub-tropical areas, mainly in Asia, Europe, Africa and the Americas. At present, there is no effective treatment for this disease. In the search for new rational chemotherapeutic alternatives, two novel trans [Pt(Hpy1)₂(Cl)₂] (1) and trans [Pt(Hpy2)₂ (Cl)₂] (2) complexes were synthesized by the reaction of K₂PtCl₄ with sterol hydrazone ligands 20-hydrazone-pyridin-2-yl-5α-pregnan-3β-ol (Hpy1) and 22-hydrazone-pyridin-2-yl-chol-5-ene-3β-ol (Hpy2). These organic compounds are specific inhibitors of sterol methyl transferase (SMT). The new platinum complexes were characterized by a combination of ESI-MS (electrospray ionization-mass spectroscopy), UV-vis, infrared and NMR spectroscopies; elemental analysis and molar conductivity. Promastigotes of Leishmania (L.) mexicana were treated for 48 h with 10 μM of the sterol hydrazones Hpy1 or Hpy2 alone or coordinated to Pt. Hpy1 produced higher leishmanistatic activity than Hpy2 (39% growth inhibition vs. 16%), which significatively increased (71%, p < 0.001) when the complex trans-[Pt(Hpy1)₂(Cl)₂] was used. This complex represents a new chemotherapeutic alternative to be evaluated in depth in experimental models of leishmaniasis.     

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.