IFNG and tuberculosis: The ELISpot IFN-γ assay was carried out with freshly prepared PBMC from TB patients and BCG+ subjects and with frozen cells from BCG- individuals, after preliminary analysis to confirm that there was no difference between the results obtained with freshly prepared and frozen cells from BCG+ controls (n = 5): no significant difference was observed for Erp, ESAT-6, Ag85B, PPD or PHA (p > 0.05) between the two cell preparations.