FIG. 5.

Scattergram showing the titers of individual ARF, UNC, AGN, and normal sera tested against peptide C3 by ELISA. Titers of each individual serum are shown in the scattergram. Sera were diluted 1:100, and twofold dilutions were performed in PBS. Peptide C3 was coated onto Immunlon 4 microtiter plates at 50 ml/well of a 10-μg/ml solution. The dilutions were added to washed wells, and the ELISA was performed as described previously. OD was read at 405 nm, and an endpoint of 0.3 was used to calculate the titer. Triangles represent carditis patient sera, and a square shows the titer of a normal serum pool from five normal individuals. Individual sera are represented by single dots. Mean titers (± standard deviations) are designated by dashed lines and were calculated for the ARF group (741 ± 950), the UNC group (1,825 ± 3,562), the AGN group (250 ± 292) and the NOR group (112 ± 35). A comparison of the ARF, UNC, and AGN groups with the NOR group yielded the following P values: for ARF versus NOR, P = 0.03; for UNC versus NOR, P = 0.004; and for AGN versus NOR, P = 0.336. ARF and UNC groups were significantly different from the NOR and AGN groups. In addition, the P value for ARF versus AGN was 0.09.