Rat retinal müller cells express Thy‐1 following neuronal cell death

In the normal rat retina the Thy‐1 antigen is a specific marker of ganglion cells, but degeneration of ganglion cells in vivo does not remove completely the expression of Thy‐1 in the retina. To reconcile these differences we have postulated that ganglion cell death could induce a glial response including the expression of Thy‐1 in Müller cells, the main glial cell type in the retina. Using immunocytochemistry, we have shown that pure cultures of Müller cells were strongly labelled with antibodies against Thy‐1. PCR amplification of cDNA reverse transcribed from Müller cell RNA indicated the presence of Thy‐1 transcripts. Double labelling experiments with anti‐Thyl and anti‐glutamine synthetase, a marker of Müller cells, indicated the presence of both antigens in the same cells. Although Müller cells expressed Thy‐1 mRNA and protein when cultured in the absence of neuronal cells, when co‐cultured with retinal neurons they were not labelled with antibodies against Thy‐1. Our results suggest that Thy‐1 is expressed by Müller cells following loss of retinal neurons. Thy‐1 may have an important function during glial response to neuron death in retina. © 1995 Wiley‐Liss, Inc.