Anti-recoverus antibodies cause apoptotk death of photoreceptor cells in vivo

Purpose. Autoantibodies against recoverin arc associated with autoimmune cancerassociated retinopath} (CAR) syndrorm. The purpose of this stud> was to examine the pathogenic role of anti-recoverin antibodies in CAR using an animal model. Methods. Lewis rats were injected intravitreally or intravenously with purified biolinvlated rat monoclonal antibodk-s specific to recoverln. Control animals recciled normal lat lgCi or saline instead of MAb. Titer and specificity of antibodies llcrc determined by El.ISA. L;yes were collected at different time after immunization and examined for ihe presence of antibodies in the retina bl immunofluorescence using Texas Red. Apopîolic cells were determined by in situ labeling using terminal dlTP nick end labeling ( IVNEL). Results. The presence of anti-recoverin antibodies was detected in the photoieceptor cell layer 24 hr aller injection of antibodies. The rnosl intense staining of the outer nuclear la; er of retina was observed after 48 hi. it faded after % hr and was not detectable 7 days post immunisation. In both experiments, after intravitreal and intravenous administration of anti-recoverin MAhs. a high number of TirNEL labelled photoreceptor cells was observed after the presence of antibodies was not detectable. This effect was time dependent: the number of apoptotic ceils increased with lime. Apoptotie cells were not detected in the retinas of the control animals receiving normal Ig(j. Conclusions. These studies strongly support our hypothesis that autoimmumU plays a role in cancer associated retinopath}. Pathogenic anti-recoverin antibodies can cross blood retinal barrier, enter the photoreceptor cells, and cause cell death by apoptosis that lead to loss of lision.