Resultados de un programa de pesquisa prenatal de la talasemia grave / Results of an antenatal screening programme for beta-thalessemia

Objetivos: Detectar el rasgo beta-talasémico durante el control prenatal de mujeres en la primera etapa del embarazo; reducir el nacimiento de niños homocigotos con beta-talasemia. Métodos: Se incluyeron embarazadas de hasta 18 semanas de gestación con antecedentes de no más de 3 embarazos, que asistían a una clínica de control prenatal. Se realizó una pesquisa mediante la estimación del volumen corpuscular medio, la hemoglobina corpuscular media y la prueba NESTROF. Se controló también a los esposos de las mujeres con pruebas positivas. Si ambos padres eran positivos, se confirmó el diagnóstico por medio de cromatografía líquida de alto rendimiento. Para la detección fetal de las parejas positivas se efectuó biopsia de vellosidades coriónicas o amniocentesis. Se ofreció la interrupción del embarazo a las mujeres con fetos con talasemia grave. Resultados: Se efectuó la pesquisa a 17339 madres en el período comprendido entre octubre de 1999 y marzo de 2010. Las pruebas de cribado fueron positivas para el volumen corpuscular medio, la hemoglobina corpuscular media y la pruebas de NESTROF en el 11.02%, 18.76% y 12.62% de las embarazadas, respectivamente. El 1.98% de las mujeres eran portadoras confirmadas. Un total de 54 parejas requirieron pruebas diagnósticas prenatales fetales. Se detectó talasemia grave en 19 fetos; todos esos embarazos fueron interrumpidos. Se encontró rasgo talasémico en 16 fetos. Conclusión: La pesquisa prenatal de la beta-talasemia es un abordaje rentable para evitar el nacimiento de niños afectados, en especial en países de alta prevalencia.

Enumeration of CD4 and CD8 T lymphocytes in healthy HIV seronegative adults of northwest India: a preliminary study.

CD4 T lymphocyte count is used to measure the progression of HIV infection and to monitor the response to antiretroviral therapy. Information on reference CD4 and CD8 T cell counts in healthy individuals is lacking in northwest India. Samples from 65 HIV-seronegative healthy volunteers (males, 37; females, 28) aged 18 through 59 years were analyzed using FACS (Fluorescent Antibody Cell Sorter) Count TM System. The values of mean and standard deviation of each lymphocyte subpopulation were estimated. The mean +/- SD of absolute numbers of CD4 and CD8 lymphocytes/microl was 743.4 +/- 307.8 and 541.7 +/- 176.4 in males and 790.7 +/- 280.4 and 497.03 +/- 203.6 in females respectively. The range of CD4 counts was 379 to 1800 in males and 321 to 1265 in females. The mean CD4:CD8 ratio was 1.43 +/- 0.56 in males and 1.78 +/- 0.76 in females. The results of this study show a wide variability in CD4 counts in the Indian population. A large multicentric study would define normal ranges of CD4, CD8, and CD4:CD8 ratios among the Indian population.

Isolation and analysis of circulating tuberculous antigens in Mycobacterium tuberculosis.

BACKGROUND: Serological techniques like enzyme linked immunosorbent assay (ELISA) and immunoblotting are useful for detection of mycobacterial antigens of diagnostic importance in tuberculosis. AIM: To isolate and identify circulating tuberculous antigens reactive with sputum positive and sputum negative pulmonary tuberculosis (PTB) sera. METHODS: Circulating tuberculous antigen was isolated by ammonium sulphate fractionation from the sera of sputum positive and sputum negative (clinically and radiologically diagnosed) PTB cases. The circulating antigen fractions and individual patients' serum samples were resolved by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting was performed using anti M.tb sonicate IgG as a probe to detect antigens. RESULTS: Anti M.tb sonicate IgG was found to be reactive with mycobacterial proteins 170 kDa, 140 kDa, 85 kDa, 55 kDa, 43 kDa, 20 kDa and 16 kDa in the antigen fraction isolated from sputum positive tuberculosis sera by immunoblotting. However only 85 kDa, 55kDa, 43 kDa and 20 kDa antigenic proteins were found to be recognized by anti sonicate IgG in the antigen isolated from sputum negative sera. These observations were further confirmed by analysis of individual S+ and S- PTB serum by immunoblotting. CONCLUSION: Seroreactive studies of circulating tuberculous antigens showed the presence of 170 kDa, 140 kDa, 85 kDa, 55 kDa, 43 kDa, 20 kDa and 16 kDa protein antigens in sputum positive sera, while 85 kDa, 55 kDa, 43 kDa and 20 kDa antigens were found to be present in sputum negative PTB which need further evaluation for their use in serological diagnosis of tuberculosis.

Serodiagnosis of childhood tuberculosis by ELISA.

OBJECTIVE: Diagnosis of childhood tuberculosis remains an enigma despite many recent technological developments. The present study has been taken up with the aim to assess the diagnostic potential of mycobacterium tuberculosis excretory-secretory ES-31 antigen and affinity purified anti ES-31 antibodies in the serodiagnosis of different spectrum of childhood tuberculosis. METHODS: Mycobacterium tuberculosis H37Ra excretory-secretory antigen (ES-31) and affinity purified goat anti ES-31 antibodies were used in stick penicillinase ELISA for IgG antibody detection and stick Sandwich penicillinase ELISA for detection of circulating free and immune complexed antigen in the sera of 230 children. RESULTS: Analysis of tubercular antibody, circulating free and immune complexed antigen (CIC-Ag) was done in both pulmonary and extrapulmonary form of childhood tuberculosis and overall sensitivity of 81.4% with a specificity of 93% was achieved for detection of antitubercular IgG antibodies. Of the five cases of pulmonary tuberculosis showing absence of IgG antibody, 3 showed the presence of CIC-Ag and one was found positive for both free and CIC-Ag. Similarly out of 8 cases of extrapulmonary childhood tuberculosis missed by IgG detection 5 were found to be positive for CIC-Ag and 1 showed the positive reaction for both free and immune complexed antigens. CONCLUSION: IgG antibody to excretory-secretory antigen ES-31 is found to be having good specificity with acceptable sensitivity in detecting different forms of childhood tuberculosis. Further detection of circulating free and/or immunecomplexed antigen can be used as an adjunct tool in the diagnosis of childhood tuberculosis.

Levels of antibody, free antigen and immune-complexed antigen by ELISA in different grades of sputum positive patients of pulmonary tuberculosis.

The ES-31 (31 kDa protein) antigen was isolated from culture filtrate of Mycobacterium tuberculosis H37Ra and was shown to have potential in immunodiagnosis of pulmonary tuberculosis. Serum samples from 38 confirmed sputum positive pulmonary tuberculosis patients were grouped into AFB+, AFB++, AFB+++ based on sputum bacillary load. Analysis of tubercular antibody, circulating free and immune complexed antigen (CIC-Ag) was done in serum samples by Indirect and Sandwich ELISA using ES-31 antigen and affinity purified anti ES-31 antibody respectively. The analysis of Geometric mean titre (GMT) of all the three groups showed that GMT of tubercular antibody was considerably decreased compared to elevated levels of CIC-Ag (Antibody: 1360 to 816 and CIC-Ag: 534 to 1744) from low bacillary sample to high bacillary samples, whereas there is no significant change in the titre of circulating free antigen. Low levels of detectable antibody is observed possibly due to removal of antibody from circulation by immune complex formation as confirmed by its elevated levels in sputum AFB+++ positive patients.

Seroreactivity of 31 kDa and 41 kDa mycobacterial secretory proteins isolated from culture filtrate in extra pulmonary tuberculosis.

Despite rapid advances in molecular genetics for detection of mycobacteria, it is clear that interest in serodiagnosis remains high, especially for those situations in which a specimen may not contain the infecting agent in particular in extrapulmonary tuberculosis. Immune response to excretory-secretory (ES) proteins of Mycobacterium tuberculosis (M.tb) has been of diagnostic interest in tuberculosis. In earlier study from our laboratory, a secretory protein M.tb ES-31 has been shown to have diagnostic potential in pulmonary tuberculosis. Further, another M.tb H37Ra ES protein (ES-41) was isolated and purified by trichloroacetic acid solubilization followed by Fast Performance Liquid Chromatography (FPLC). These two protein fractions viz ES-31 and ES-41 secreted by M.tb H37 Ra bacilli were employed in stick indirect penicillinase ELISA to study seroreactivity in extra pulmonary tuberculosis namely tuberculous lymphadenopathy, tuberculous meningitis, abdominal tuberculosis and bone & joint tuberculosis. While using ES-31 antigen 88% (22/25) of tuberculous lymphadenopathy and 90% (9/10) of tuberculous meningitis cases showed positive reaction for tuberculous IgG antibody, ES-41 showed 80% positivity in both groups. In abdominal and bone & joint tuberculosis cases, ES-41 antigen showed better sensitivity of 81.5% (22/27) and 84.6% (22/26) respectively in IgG antibody detection compared to 70% (19/27) and 69.2% (18/26) shown by ES-31. This study is of interest that different antigen protein fractions of M.tb exhibit differential seroreactivity, as ES-31 protein showed good potential in detecting tuberculous IgG antibodies in tuberculous lymphadenopathy (TBLN) & tuberculous meningitis (TBM), while ES-41 in abdominal and bone & joint tuberculosis cases.