Bystander killing of neurons by cytotoxic T cells specific for a glial antigen.
To explore pathways to neuron loss in inflammatory diseases, transgenic mice expressing beta-galactosidase (beta-gal) in either astrocytes or photoreceptor cells, or both, were inoculated with activated, beta-gal-specific cytotoxic CD8 T lymphocytes (CTLs). beta-gal-positive astrocytes in brain were rapidly attacked, with particular damage in cerebellum. Substantial loss of cerebellar granule cells was found, even though these neurons did not express beta-gal. The small number of beta-gal-positive retinal astrocytes present in these mice was also rapidly destroyed by transferred CTLs, but without detectable consequences for retinal neurons. However, in mice with photoreceptor cell-specific beta-gal expression, near-total destruction of photoreceptor cells was produced by CTL transfer. Attack on photoreceptor cells displayed minimal inflammation, and onset was a week later than onset of astrocyte-directed disease. CTL transfer into F1 mice expressing beta-gal in both astrocytes and photoreceptor cells confirmed that pathogenesis directed against antigen expressed in glia versus neurons proceeded in two distinct, independent phases. beta-gal-positive retinal astrocytes were severely affected by 5 days post-transfer, followed by rapid resolution. Photoreceptor cells in the same retina were unaffected until 12 days post-transfer. The susceptibility of photoreceptor cells was not enhanced by the prior CTL attack on beta-gal-expressing retinal astrocytes. The results demonstrate that extensive bystander killing of neurons can occur in vivo as a result of direct CTL attack on surrounding astrocytes. Antigen-expressing retinal neurons were also efficiently killed by CTLs, but by a mechanism that was substantially delayed and dissociated from the killing of retinal astrocytes.
McPherson
Scott W
SW
Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Heuss
Neal D
ND
Roehrich
Heidi
H
Gregerson
Dale S
DS
D000818:Animals; D001253:Astrocytes / Q000473:pathology / Q000502:physiology; D001259:Ataxia / Q000473:pathology / Q000503:physiopathology; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D002460:Cell Line; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D009457:Neuroglia / Q000473:pathology / Q000502:physiology*; D009474:Neurons / Q000473:pathology / Q000502:physiology*; D009900:Optic Nerve / Q000166:cytology / Q000473:pathology; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology / Q000473:pathology; D012160:Retina / Q000166:cytology / Q000473:pathology; D013602:T-Lymphocytes, Cytotoxic / Q000473:pathology / Q000502:physiology*; D001616:beta-Galactosidase / Q000276:immunology*
D005904:Glial Fibrillary Acidic Protein; D001616:beta-Galactosidase