(a)
(b)
(c)
(d)
Figure 3: Correlations of IgA antibody levels in serum of latently M. tuberculosis infected individuals. Scatter graphs showing the relations between anti-AlaDH IgA and anti-19 kDa IgA (a), anti-NarL IgA and anti-19 kDa IgA (b) and anti-AlaDH IgA and anti-AlaDH IgG (c) as well as anti-NarL IgA and anti-PstS3 IgA (d) using the optical density (OD) values in diluted sera (). The correlation coefficient and the value were calculated using the Spearman rank test. The hexagon with a dot in its center characterizes the progressor to active TB, whereas all other latently M. tuberculosis infected individuals are characterized by the symbol .