Development and use of ELISA to quantify type II phospholipase A2 in normal and uremic serum

Previously we reported that uremic plasma contained eight times more phospholipase A2 (PLA2) activity than control plasma (Costello et al., Clin Chem 1990;36:198-200). That study, however, did not distinguish between various PLA2s that could contribute to the observed increase. Therefore, we developed a sandwich ELISA to specifically quantify serum type II PLA2. By ELISA, uremic sera contained significantly more type II PLA2 than control sera (median = 1025 micrograms/L, range = 52-3320 micrograms/L vs median = 9.2 micrograms/L, range = 4.6-17.5 micrograms/L; P = 0.002). When serum samples were incubated with 1-[14C]oleate-labeled autoclaved Escherichia coli, activity was increased 14.6-fold in uremic vs normal serum, with a median of 6.5 mumol/min per liter (range 1.1-16.3) vs a control median of 0.49 mumol/min per liter (range 0.32-0.60; P = 0.002). Thus, ELISA detects about eightfold more immunoreactive type II PLA2 in uremic serum than does enzymatic analysis. Evidently, the increase in PLA2 activity previously observed in uremic plasma is primarily due to increased concentrations of type II PLA2.