DIFFERENTIAL EXPRESSION OF CARBONIC-ANHYDRASE ISOZYMES IN MICROGLIAL CELL-TYPES

Microglial cells have been shown to express carbonic anhydrase. Using carbonic anhydrase histochemistry and immunohistochemistry, different types of central nervous system microglial cells were detected, which expressed two main carbonic anhydrase (CA) isozymes during the early p ostnatal stage of development and after peripheral nerve injury in the spinal cord of adult rats. Amoeboid and reactive microglial cells wer e heavily immunostained for CA-II and CA-III and showed colocalization with complement receptor type 3 and Griffonia Simplicifolia B4 isolec tin. Resting microglial cells in the brain and spinal cord showed fain t CA-III staining and were negative for CA-II. These results show that not only CA-II, but also CA-III isozyme is represented in the central nervous system and carbonic anhydrase activity may correlate with met abolic and immunological changes of microglial cells. These data also further strengthen the idea of the mesodermal origin of central nervou s system macrophages.