Analysis of uveitogenic sites in phosducin molecule.
OBJECTIVE
Phosducin, a retinal photoreceptor protein, induces experimental autoimmune uveitis (EAU). In this study, we attempted to determine the numbers of uveitogenic sites in phosducin using synthetic peptides.


METHODS
Antigen peptides were synthesized according to the amino acid sequence of the rat-derived phosducin with a peptide-synthesizer and purified by reversed-phase HPLC. First, 13 peptides covering the entire sequence of phosducin were synthesized, and each was injected into the hind footpad of Lewis rats for immunization, and induction of EAU was examined clinically and histologically. Next, peptides that appeared to contain sequences of a uveitogenic site were newly synthesized and examined clinically and immunologically.


RESULTS
Of the 13 peptides used in the first immunization, 7 induced inflammation. Similar to other EAU antigens, clinical changes began with fibrin deposition in the anterior segment and posterior synechia, followed by posterior chamber hypopyon. Histologically, inflammation was observed mainly in the outer segment of photoreceptor cells and outer nuclear layer, and serous retinal detachment was found in cases of severe inflammation. Infiltration of inflammatory cells in the pineal gland was also observed. In experiments designed to further specify the uveitogenic sites, the presence of inflammation-inducing sequences was inferred for amino acid sequences 1-20, 23-37, 79-91, 127-142 and 198-212. The rats immunized with these peptides also exhibited high value on lymphocyte proliferation assay.


CONCLUSIONS
Phosducin has 5 uveitogenic sites. Among others, one of them has potent and others weak uveitogenicity.
Department of Ophthalmology, Akita University School of Medicine, Akita city, Japan.
N
N
Satoh
T
T
Abe
A
A
Nakajima
M
M
Ohkoshi
T
T
Koizumi
H
H
Tamada
S
S
Sakuragi
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000032:analysis; D001327:Autoimmune Diseases / Q000276:immunology* / Q000473:pathology; D002455:Cell Division / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000235:genetics* / Q000276:immunology*; D005260:Female; D020555:GTP-Binding Protein Regulators; D007114:Immunization; D008214:Lymphocytes / Q000473:pathology; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics* / Q000276:immunology*; D010786:Photoreceptor Cells / Q000473:pathology; D051381:Rats; D011917:Rats, Inbred Lew; D012882:Skin Tests; D014605:Uveitis / Q000276:immunology* / Q000473:pathology
D000906:Antibodies; D005136:Eye Proteins; D020555:GTP-Binding Protein Regulators; D010750:Phosphoproteins; C065631:phosducin