Additional file 2 of No impact of helminth coinfection in patients with smear positive tuberculosis on immunoglobulin levels using a novel method measuring Mycobacterium tuberculosis-specific antibodies

Supplementary Material 2: Supporting information S2 Fig. Higher Mtb-specific IgG1 and IgG2 response against Mtb cell membrane fraction than against PPD in plasma of Peruvian TB patients: Mtb-specific antibodies in plasma was analyzed using ELISA-plates coated with purified protein derivative from Mtb (PPD) or Mtb strain CDC1551 cell membrane fraction (CDC1551), and using either HRP-conjugated anti-IgG1 (1/800 dilution of plasma) (A), or HRP-conjugated anti-IgG2 (1/400 dilution of plasma) (B). Plasma was from Peruvian controls that were helminth negative and healthy (n = 15), and helminth negative pulmonary TB patients (Helminth-/TB+; n = 9). Data are presented as scatter plot bar graphs with each symbol (circle, PPD; triangle, CDC1551) representing a single individual and bars depicting mean ± SEM of the OD450-value after background subtraction of antigen-coated wells receiving wash buffer instead of plasma but otherwise treated the same. (C) Gel electrophoresis for separation of the Mtb antigens was performed on a 10% SDS-polyacrylamide gel and total protein evaluated by silver staining. 7.5 µg of each antigen was loaded onto the gel. Lane 1: CDC1551 cell membrane fraction of Mtb. Lane 2: purified protein derivative from Mtb (PPD). Lane 3: protein standard from Bio-Rad