Abstract
Nine lines of monoclonal IgM antibodies to rat brain glutaminase were produced from a mouse. The antibodies were named MAb-19, -21, -45, -48, -51, -55, -59, -97, and -120. Immunotitration tests revealed that six of the nine antibodies (MAb-19, -21, -45, -48, -97, and -120) absorbed dose-dependently more than 75% of glutaminase activity in rat brain. By immunoelectroblotting after gel electrophoresis of the homogenate, all antibodies showed a positive band at the same position as that of the purified enzyme. However, MAb-55, -59, and -97 crossreacted with other proteins. Despite the difference in their specificities, all of the antibodies except MAb-51 competed with one another for determinants on the enzyme. The competition test further indicated that the affinities of the antibodies were in the order MAb-120 greater than -21 greater than -48 greater than -19 not equal to -45 greater than or equal to -97 greater than or equal to -55 greater than or equal to 59. When applied to immunohistochemical staining of cerebral cortex of rat brain, the five specific antibodies (MAb-19, -21, -45, -48, and -120) produced essentially the same pattern of neuronal labeling; they labeled specifically pyramidal neurons, which are reportedly glutamatergic. The most intense labeling was obtained with MAb-120.