Evaluation of a multi-antigen test based on B-cell epitope peptides for the serodiagnosis of pulmonary tuberculosis.

SETTING: Two sample panels: 1) 20 pulmonary tuberculosis (PTB) patients and 10 healthy subjects from a country with a low incidence of TB (Italy); and 2) 47 PTB patients and 26 healthy subjects from a country with a high incidence of TB (Morocco). OBJECTIVE: To identify a combination of Mycobacterium tuberculosis peptides useful for the serodiagnosis of active PTB. METHODS: Fifty-seven B-cell epitope peptides of M. tuberculosis were evaluated by immunoenzymatic assay and the data were analysed using logistic regression analysis and the random forest method. RESULTS: The best discriminating peptide between PTB patients and healthy subjects from the sample of the low TB incidence country was the 23 amino acid peptide of the Rv3878 protein. The sensitivity and specificity were respectively 65% and 100%. The same peptide had a sensitivity and specificity of respectively 47% and 100% for the sample from the high TB incidence country. The best combination of peptides was a pool of nine peptides which had a sensitivity of 70.2% and a specificity of 100% in the high TB incidence country. CONCLUSIONS: The 9-peptide pool can be useful in identifying patients with active PTB.

[Low prevalence of anti-centromere antibodies in scleroderma in Morocco (about 272 cases)]. / Faible prévalence des anticorps anti-centromère dans la sclérodermie au Maroc (à propos de 272 cas).

PURPOSE: assessment of autoantibodies prevalence during scleroderma within a Moroccan population by a retrospective survey. MATERIAL AND METHODS: 272 patient (220 cases of systemic sclerosis, 45 cases localised scleroderma and 7 cases of mixed connective tissue disease (MCTD)) underwent a screening for antinuclear antibodies (ANA) by indirect immunofluorescence (IFI) on Hep-2 cells, followed, in 127 cases, by anti-extractable nuclear antigen (ENA) antibodies identification using a double immunodiffusion (IDD) method. RESULTS: sixty eight for percent of patients presenting with a systemic sclerosis had positive ANA whose identification revealed: 23 cases (15.3%) of anti-topoisomerase I, 8 cases (5.3%) of anti-centromere (ACA) and 5 cases (3.3%) of anti-U1-RNP antibodies. Out of the 8 cases of ACA, 3 corresponded to a CREST syndrome. Anti-topoisomerase I antibodies were observed in 2 of the 4 patients having an interstitial pulmonary syndrome. Anti-U1-RNP antibodies were present in 3/38 patients (7.8%) having a systemic sclerosis associated to arthritis. 4/45 patients (9%), presenting with a localised scleroderma, had positive ANA, of which 2 were ACA. All patients admitted for MCTD had anti-U1-RNP antibodies, coexisting with anti-Sm antibody in 2 cases. CONCLUSION: the low prevalence of ACA observed in this survey, when compared to American, European and Japanese studies, is probably due to ethnic variation in frequency of ANA. Indeed, low rates or absence of ACA have been reported in south-African, Afro-American, Indian, and Thai studies. The IDD, method of reference for detecting of anti-ENA antibodies, identify a small fraction of anti-nucleolar aspects of scleroderma. Thus, other methods such as ELISA and/or immunoblotting are required to complete their identification.