Fig. 4.

Relationship of antibodies to PPD in plasma samples and enhancement of TNF-α secretion. Spearman Rank correlation analysis (two-tailed exact Fisher test) was carried out to determine the correlation. between TNF-α secretion and the concentrations of IgG1 and IgG3 antibodies to PPD in plasma samples (n = 8). Each • represents the average of results obtained from seven donors (± SEM), shown as vertical lines. Antibody concentration is given as units of activity. (a) Antibody activity for IgG1. (b) Antibody activity for IgG3 anti PPD antibodies. The significance of correlation (P-values) is given for antibody subclasses.