Pseudomonas aeruginosa antibodies in human plasma

Plasma samples from healthy adults were examined for antibodies to the common protective antigen (OEP) [1] by passive hemagglutination (HA) reaction [2] with the finding that the majority of them had an antibody titer of 60 or lower. 2-Mercaptoethanol (2-ME) treatment, however, caused a decrease in HA titer down to 16 or lower in most of the cases, suggesting that the OEP antibody resides mostly in IgM and slightly in IgG. The finding was corroborated by gel filtration on Sephadex G-200. It appears likely that IgA is not implicated in the HA titer since IgA was HA negative. However, the detection of enzymatic activity by enzyme-linked immunosorbent assay (ELISA) [9] still suggests a possibility that OEP antibody resides in IgA. On the other hand, antibodies to proteolytic enzymes, especially protease and elastase [3], elaborated by Pseudomonas aeruginosa, were found to be present in most cases at a titer of 16 or lower by HA reaction. It was also found that they reside mostly in IgM.