The need for standardization of antiretinal antibody detection and measurement

Plasma Antiretinal Autoantibody Profiling and Diagnostic Efficacy in Patients With Autoimmune Retinopathy

PURPOSE

To evaluate plasma antiretinal autoantibody (ARA) profiling and diagnostic efficacy for autoimmune retinopathy (AIR).

DESIGN

A multicenter, diagnostic evaluation study.

METHODS

Forty-nine patients with a clinical diagnosis of AIR, disease controls including 20 patients with retinitis pigmentosa (RP), and 30 normal controls were included. Plasma samples from patients were analyzed for the presence of 6 ARAs, including recoverin, α-enolase, carbonic anhydrase II, heat shock protein 60, aldolase C, and cone-rod homeobox/cone-rod retinal dystrophy 2 using western blotting.

RESULTS

Autoantibody detection rates against cone-rod homeobox/cone-rod retinal dystrophy 2, heat shock protein 60, and aldolase C in AIR were 67.3%, 40.8%, and 42.9%, respectively, which were higher than those in RP and normal controls (P < .001, P < .001, and P = .007, respectively), but recoverin, α-enolase, and carbonic anhydrase II were not different from other control groups (P = .117, P = .774, and P = .467, respectively). Among ARAs, antirecoverin antibody was the most specific, as it was found in 3 (6.1%) patients with AIR and none of the control groups. As the number of detected ARAs increased, the probability of AIR increased (odds ratio: 1.913; P < .001; 95% confidence interval: 1.456-2.785). The positive number of ARAs was significantly higher when photoreceptor disruption was observed on optical coherence tomography, or severe dysfunction was observed in electroretinography (P = .022 and P = .029, respectively).

CONCLUSIONS

The profiles of ARAs in the AIR group were different from those in the RP and normal controls. The higher number of positive ARAs suggests a higher possibility of AIR diagnosis. ARAs should be used as adjunct tools for the clinical diagnosis of AIR.

Serum anti-recoverin antibodies is found in elderly patients with retinitis pigmentosa and cancer

PURPOSE

To screen for anti-recoverin antibodies in elderly patients with retinitis pigmentosa (RP) with or without cancer and cross-sectionally characterize the seropositive patients clinically.

METHODS

Serum from 75 RP patients who had been tested for mutations in a panel of 83 RP genes and 73 normal controls, all aged 50-80 years, were screened for anti-recoverin antibodies by Western blot using recombinant recoverin, retinal lysate from a marmoset and commercial anti-recoverin antibodies as a control.

RESULTS

Three RP patients with typical pigmentary degeneration of the 75 (4.0%) were seropositive for anti-recoverin antibody. Pathogenic mutations were identified in two seropositive RP patients. All three patients had visual impairment since childhood and were diagnosed as RP by the age of 30. The severity of the retinopathy varied greatly among these three patients, ranging in visual acuity from light perception OU to 20/30 OU. Retinitis pigmentosa (RP) patients with a history of cancer were more likely to have anti-recoverin antibodies (3/14; 21.4%) than those without (0/61; 0%; p = 0.005, Fischer exact test). All 73 healthy controls with no history of cancer were also seronegative.

CONCLUSION

Our results show that serum anti-recoverin antibodies can be detected in typical RP patients with identified pathogenic mutations and that a history of cancer may increase the risk of developing anti-recoverin antibodies.

Autoantibody profiling in intraocular fluid of patients with uveitis

A high prevalence of serum antiretinal antibodies (ARAs) in patients with uveitis has been previously described, though their clinical role remains elusive. Assessment of intraocular ARAs may provide further insight into the pathogenesis of diverse uveitis entities. In this study we investigate the prevalence of multiple specific anti-ocular antibodies (AOcAs), including ARAs, in intraocular fluid of patients with uveitis. Autoantibody profiling with 188 different ocular antigens was performed by a multiplex immunoassay with intraocular fluid samples of 76 patients with uveitis. Clinical data from uveitis patients were collected and statistical analyses were executed to evaluate associations between intraocular AOcAs and clinical characteristics. Controls consisted of 19 intraocular fluid samples from cataract patients. A spectrum of 22 different AOcAs was present in higher levels in patients with uveitis than in controls (p < 0.05), but in moderately elevated titers (<2x). High elevations of intraocular AOcAs in uveitis (>5x compared to cataract) were observed in varicella zoster virus-induced uveitis, multiple sclerosis-associated uveitis and patients with unexplained uveitis but positive quantiferon test. Presence of macular edema was associated with increased intraocular levels of tyrosinase antibodies. Our results show that patients with uveitis are characterized by the presence of a broad spectrum of moderately elevated levels of intraocular AOcAs, and high intraocular AOcA levels were found in several specific uveitis entities. This study favors secondary production of AOcAs and not their inciting role.

Diagnostic features of the autoimmune retinopathies

The term autoimmune retinopathy encompasses a spectrum of rare autoimmune diseases that affect retinal function, often but not exclusively at the level of the photoreceptor. They typically present with painless visual loss, which may be accompanied by normal fundus examination. Some are progressive, often rapidly. They present a diagnostic challenge because there are no standardised clinical or laboratory based diagnostic criteria. Included within the spectrum are cancer-associated retinopathy, melanoma-associated retinopathy and presumed non-paraneoplastic autoimmune retinopathy. Differentiation from other retinopathies can be challenging, with overlap in symptoms, signs, and investigation findings, and an absence of pathognomonic features. However, technological developments in ophthalmic imaging and serological investigation over the past decade are adding novel dimensions to the investigation and classification of patients with these rare diseases. This review addresses the clinical, imaging, and serological features of the autoimmune retinopathies, and discusses the relative strengths and limitations of candidate diagnostic features.