ODI of Anti-PPD Antibody in Pleural Effusion

The mean ODI values of anti-PPD IgG, IgA and IgM antibodies in tuberculous effusions were 0.49±0.19 (mean±SD), 0.72±0.39 and 1.02±0.24. They were significantly higher (p<0.01 in anti-PPD IgG and IgA antibodies, p<0.05 in IgM antibody) than those (0.37±0.11, 0.46±0.27 and 0.86±0.25) in carcinomatous antibodies (IgG in Fig 1, IgA in Fig 2). Defining the cut-off values as mean ODI -I- 2SD in malignant pleural effusions, we calculated the accuracy of anti-PPD antibody estimation for diagnosis of tuberculous pleural effusion. The IgG antibody sensitivity was 7/31 (22.6 percent), specificity 37/39 (94.9 percent), positive predictive value 7/9 (77.8 percent) and efficiency 44/70 (62.9 percent). A positive correlation was confirmed between ODI values of anti-PPD IgG and IgA antibodies in tuberculous pleural effusions (p<0.05), but no relationship was found among antibodies in malignancy. Patient age did not correlate with ODI values.

FIGURE 1. The ODI values of anti-PPD IgG antibodies in pleural efiusions. There is a significant difference (p<0.01) between tuber-culous and malignant pleurisy. Average value ±SD was displayed by open circle and bars.

FIGURE 2. The ODI values of anti-PPD IgA antibodies in pleural efiusions. There is a significant difference (p<0.01) between tuber¬culous and malignant pleurisy. Average value ±SD was displayed by open circle and bars.

Analysis of Detected PPD and BCG Whole Cell Fraction Antigens

The PPD antigen was stained with CBB and PAS after SDS-PAGE. In Figure 3, many protein bands with CBB stain and three broad bands (below 20 Kd, 30 to 40 Kd, 55 to 80 Kd) with PAS stain were observed. Figure 4 shows the representative immunostain of PPD and BCG whole cell fraction antigens recognized by IgG antibody in pleural effusions. The blotted paper demonstrated a broad band from 25 to 40 Kd molecular weight region in each specimen. Another band from 14 to 22 Kd was also found in some samples. Every immunostain positive paper included 25 to 40 Kd band, so we considered that it was the main antigen of PPD and BCG whole cell fraction. The IgG antibody reactive with this 25 to 40 Kd band was positive in seven of 17 tuberculous effusions examined and in only one of 18 malignant ones. This band did not change with or without the presence of 2-mercaptoethanol, nor did it change with heat for one hour at 100°C (data not shown).
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FIGURE 3. The CBB and PAS stains of PPD antigens. More than ten protein hands in CBB stain and three broad ones (below 20 Kd, 30 to 40 Kd, 55 to 80 Kd) in PAS stain are observed.

FIGURE 4. Immunostain of antigens in BCG whole cell fraction and PPD recognized by IgG antibody in three tuberculous pleural effusions. A broad band of 25 to 40 Kd molecular weight is stained in each specimen. Another 14 to 22 Kd band is also found in one sample of BCG whole cell fraction.