Monoclonal antibodies to rabbit alpha-2-macroglobulin and their use in a sensitive ELISA assay.

alpha-2-macroglobulin (alpha-2-M), a plasma proteinase inhibitor, plays an important role in the pathogenesis of lung inflammation. The purpose of this study was to develop a sensitive ELISA assay for rabbit alpha-2-M to allow us to define the role of this protein in a rabbit model of lung inflammation/injury. Therefore, we developed hybridomas which secrete monoclonal antibodies (mAbs) against rabbit alpha-2-M. From the antibodies produced, two (5B6 and 3C5) were selected. Both of them were of the IgG1 subclass. 5B6 reacted with native alpha-2-M as well as with the "fast" form of alpha-2-M (native alpha-2-M or the "slow" form is converted to the "fast" form by reaction with a proteinase). On the other hand, 3C5 reacted only with "fast" form of alpha-2-M. With these antibodies, we developed two ELISA assays which were used to determine the concentration of alpha-2-M in the lung fluids from rabbits with lung injury.