Monoclonal Antibody Monospecific to Glycine for Brain Immunocytochemistry

We have developed mouse monoclonal antibodies (AGLY-1-8, all IgG1 subisotype mAbs) against glycine (Gly) conjugated to bovine serum albumin using glutaraldehyde (GA)-NaBH4. Among these, AGLY-4 mAb was found to be the most useful for Gly immunocytochemistry (ICC) in functions of specificity and sensitivity without non-specific immunobinding. AGLY-4 was demonstrated to be monospecific to Gly by an enzyme-linked immunosorbent assay (ELISA) binding test, and not reactive to any of the other amino acids and peptides tested. Using this antibody, indirect immunoperoxidase staining was observed in different regions of the rat brain fixed with GA in combination with borohydride reduction. In contrast, immunoreactivity was quite low in tissues fixed only with GA. Absorption controls indicated that the immunostaining could be completely inhibited by 5 microg/ml of Gly-human serum albumin (HSA) conjugate prepared using GA and NaBH4, which was consistent with the results of an ELISA inhibition test. No cross-reaction occurred with other GA-conjugated amino acids. Dense ICC staining was observed in the rat neurons related to the auditory and vestibular centers, and modest immunostaining was seen in all the structures of the cerebellar cortex except for the Golgi cells which were strongly stained. These results were in complete agreement with the previous methods using polyclonal anti-Gly serum. Also, a new finding was that staining was noticed in certain cells widely distributed in the different brain regions. These results strongly suggest that the monoclonal antibody has a potential for elucidating the precise distribution of Gly-containing cells.