Effect of purification methods on isotype subclass distribution in Ig preparations. Ig preparations purified using the various methods were tested for changes in MSP-1p42 specific IgG1 (Panel A), IgG2 (Panel B), IgG3 (Panel C) and IgG4 (Panel D) for each treatment; pre-treatment serum, Protein G, Protein A/G, CA-AS, and PEG. Immune serum was from a naturally exposed individual residing in Gabon. Data shown are the mean OD405 (± SEM) of three independent isotype subclass specific ELISA experiments. Asterisks indicate statistically significant differences (p < 0.05). Dashed lines indicate background level responses for each isotype subclass test.