Cytologie des hemopathies malignes de type myeloide a Kinshasa

Objectifs : Determiner la part de differentes entites d'hemopathies malignes myeloides et identifir leurs caracteres cytologiques et epidemiologiques. Methodes: L'etude s'est deroulee de 2004 a 2010 au sein de deux laboratoires de biologie medicale de Kinshasa. Apres la ponction medullaire a l'aiguille intramusculaire ou spinale; les frottis des patients sont colores au May Grunwald Giemsa. Les hemopathies myeloides malignes sont retenues; les variables cytologiques et epidemiologiques des patients sont etudiees. Resultats : Soixante dix neuf hemopathies malignes du tissu myeloide sont diagnostiquees sur un total de 483 malades ponctionnes. Elles sont reparties chez 52 hommes et 27 femmes. Ces hemopathies atteignent tous les ages. Leur distribution selon les tranches d'age montrait une courbe ascendante avec trois paliers : la vingtaine; la quarantaine et la soixantaine. Les entites les plus rencontrees etaient: 39;2 de leucemie myeloide chronique (LMC) et 24;1 des syndromes myelodysplasiques (SMD). La LMC predominait entre 20-39 ans ; les SMD et quelques LAM; entre 50-59 ans. Au-dela de 60 ans; on avait le grand pic des LAM et le second pic de la LMC. Conclusion : Les hemopathies malignes myeloides presentaient une tendance a l'augmentation progressive sur la duree de l'etude. Les differentes entites apparaissaient plus tot qu'a l'age decrit dans la litterature avec un taux de SMD plus important

Superiorite du polymorphisme du systeme HLA par la biologie moleculaire sur le polymorphisme par la serologie aux Cliniques Universitaires de Kinshasa

Le present travail a consiste en l'etude sur systeme HLA de classe II dans la population congolaise. Quatre vingt douze echantillons provenant des sujets sains on ainsi ete types par des methodes de Biologie moleculaire; en utilisant la technique de PCR-SSO et en comparant les resultats a ceux obtenus; par la methode serologique; dans la meme population. Trente et un; 16; 16 et 14 alleles ont ete respectivement reveles aux loci DR; DP et DQ alors que la methode serologique n'avait detecte que 11 et 3 alleles aux loci DR et DQ respectivement et aucun allele au locus DP. Parmi les alleles observes; les plus frequents sont DRBI*1501 pour le locus DRB1; DQB1*0602 pour le locus DQB1 et DPB1*01011 pour le locus DPB1. Ces resultats montrent que le polymorphisme HLA etudie par la Biologie moleculaire est de loin plus etendu que lorsqu'on l'etudie par les methodes serologiques ou celles d'Immunologie cellulaire

HLA class II polymorphism in Aka Pygmies and Bantu Congolese and a reassessment of HLA-DRB1 African diversity.

HLA-DRB1, -DQB1 and -DPB1 polymorphisms were investigated in two African populations, the Basse Lobaye Aka Pygmies of the Central African Republic, and a Bantu-speaking group from the Democratic Republic of Congo Kinshasa. Allelic and haplotypic frequency distributions reveal marked differences between the two populations in spite of their geographical proximity: the Aka exhibit high frequencies for several alleles, especially at the DPB1 locus (0.695 for DPB1*0402), probably due to rapid genetic drift, while the Bantu distributions are more even. Genetic distances computed from DRB1 allelic frequencies among 21 populations from North and sub-Saharan Africa were applied to a multidimensional scaling analysis. African populations genetic structure is significantly shaped by linguistic differentiation, as confirmed by an analysis of molecular variance. However, selective neutrality tests indicate that many African populations exhibit an excess of heterozygotes for DRB1, which is likely to explain the genetic similarity observed between some North African and Bantu populations. Overall, this study shows that natural selection must be taken into account when interpreting the patterns of HLA diversity, but that this effect is probably minor in relation to the stochastic events of human population differentiations.

Low frequency of HLA-B27 and scarcity of ankylosing spondylitis in a Zairean Bantu population.

Ankylosing spondylitis (AS) is an inflammatory rheumatic disease which is thought to be rarely seen in African Blacks. Its genetic predisposition has been stressed in Caucasians where the HLA-B27 antigen is firmly linked to the disease. In the present study, HLA-B27 antigen was determined in 146 individuals of Bantu root. Only one of these subjects was found to possess HLA-B27 antigen. This study correlates the low frequency of HLA-B27 with the observed scarcity of AS in patients attending a clinic in Kinshasa for osteoarticular diseases.

HLA-DR gene frequencies in a Zaïrean population with particular reference to rheumatic diseases.

Epidemiological studies have shown that rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus are uncommon in black Africans, and in this population the prevalence and the clinical features of these rheumatic diseases are variable. Environmental and genetic factors have been pointed out to explain this variability. In the present study, HLA-DR genes have been determined in a Zaïrean population in order to compare our results with those found elsewhere in other black populations of the same Bantu origin. Our results show that the frequency of HLA-DR1 is higher than in Nigerians, Zimbabweans and Xhosas, the decrease in Xhosas being statistically significant (p < 0.006). The HLA-DR3 frequency is higher in Zaïreans than in Nigerians but not significantly, while it is lower than in Xhosas (p < 0.003) and in Zimbabweans (not significant). The HLA-DR4 frequency is higher in Zaïreans than in Nigerians but it is lower than in Xhosas and Zimbabweans; the differences are not statistically significant. The HLA-DR8 frequency is lower in Zaïreans than in Nigerians while it is higher than in Xhosas (p < 0.002) and in Zimbabweans (not significant). These data suggest that genetic factors partly explain the clinical and epidemiological variability of rheumatic diseases in black Africans.

Therapeutic effect of an anti-HIV candidate vaccine.

A chimpanzee infected with the HIV since 8 months and presenting regularly with antigenemia was inoculated with a candidate vaccine. It received 3 doses, one dose every 15 days. Thirty days after the third injection, we noted the disappearance of the HIV antigens in the serum and its persistence in the lysate of the cells. We noted also a strong precipitation reaction both in the tube and in the gel between the antibodies and the antigens released by the lysis of the cells. The analysis of this precipitate demonstrated that it was constituted of immune complexes in which the antibodies were of high affinity. At the 240th day after the third injection of the candidate vaccine we noted the disappearance of the HIV antigens in the lysate of cells as well. From these results, we conclude that the candidate vaccine we tested can elicit high affinity antibodies able to clear the HIV antigens and destroy the cells containing the HIV antigens probably with the help of specific killer cells.

A group specific anamnestic immune reaction against HIV-1 induced by a candidate vaccine against AIDS.

The first experimental immunization of humans against the AIDS retrovirus, HIV-1, was started in a series of HIV seronegative, healthy volunteers in November 1986. For the primary vaccination recombinant vaccinia virus (V25) expressing the complete gp160 env protein of the HTLV-IIIB strain of HIV-1 was introduced by scarification. This elicited a weak primary response which we subsequently attempted to enhance by additional immunizations (boosting), using four different immunization protocols. We report here that intravenous injection of paraformaldehyde-fixed autologous cells infected in vitro with V25 (individual D.Z.) gave the best results. This individual received second and third boosts of intramuscular gp160 derived from an HTLV-IIIB clone using the hybrid vaccinia virus/bacteriophage T7 expression system. An anamnestic humoral and cellular immune reaction was achieved for over one year after the original vaccination, with high levels of antibodies to the viral envelope, and neutralizing antibodies against divergent HIV-1 strains such as HTLV-IIIB and HTLV-IIIRF (also called HTLV-III HAT) after the first boost. In addition, group-specific cell-mediated immunity and cell-mediated cytotoxicity against infected T4 cells were obtained after the primary vaccine and enhanced by the boosts. Finally, skin tests showed both immediate and delayed hypersensitivity to gp160 in vivo. Although this protocol is not practical for a large scale vaccine trial, our results show for the first time that an immune state against HIV can be obtained in man.

Genomic diversity of Zairian HIV isolates: biological characteristics and clinical manifestation of HIV infection.

We describe here several African isolates of HIV, compare them to U.S.-European prototype isolates and to each other, correlate the number of isolates with serological results, and provide insights into the disease spectrum associated with HIV infection in Africa. Three of 25 healthy Zairian donors and 54 of 87 Zairian patients selected for specific pathology and hospitalized in the internal medicine department of the University Clinic of Kinshasa, Zaire, were HIV positive over a six month period in 1985 either by serum antibody (42 cases) or virus isolation (40 cases). The virus positive cases showed a decrease in number of T4 cells and interleukin-2 (IL2) production by mononuclear cells. Restriction endonuclease analysis of HIV sequences from these isolates showed that genomic diversity is also observed in the Zairian isolates but closely related viruses could also be found, similar to the spectrum of diversity among isolates obtained from the U.S. and Europe. A number of isolates (12 of 40) were obtained from serum antibody negative adults. These results are difficult to explain by viral antigenic diversity alone since hybridization with a HTLV-III-B (clone BH10) probe under stringent conditions indicated an overall high degree of relatedness. Rather, these results indicate that some African HIV infected patients fail to make detectable antibodies to HIV or the antibodies were bound in immune complexes not detectable by current techniques.

Evidence for HTLV-III/LAV expression by primary cultures of T8 cells.

The selective targets for HTLV-III/LAV, the causal infectious agent of AIDS and AIDS-related complex (ARC), are T4 cells, apparently because the virus receptor is associated with T4 antigen determinants. This accounts for T4 cell depletion in AIDS and for a decrease of IL-2 production by AIDS peripheral blood lymphocytes (PBL) after in vitro PHA activation. By contrast, T8 cells are not targets for HTLV-III/LAV, since T8 cells from PBL and from long-term cultured T cells (CTC) could not be infected by the virus. We describe 2 samples of PBL from Zairian patients with HTLV-III infection in which HTLV-III was expressed by T8 cells. Evidence that T8 cells were expressing virus was obtained by complement cytotoxicity experiments performed in the presence of OKT8 monoclonal antibody (MAb), which removed HTLV-III-positive cells from cultured T cells producing the virus, and by double labelling experiments, in which some cells exhibit both T8 antigens detected either by IFA (rhodamine) or by rosetting in presence of OKT8 MAbs and HTLV-III antigens detected by IFA (fluorescein) with of anti-HTLV-III p24 and p15 MAbs. Since normal T cells have previously been shown to undergo antigenic diversity, we think these results can be explained by HTLV-III infection of T4 cells which later lost T4 antigens and acquired the T8 phenotype.