Braun, G.

Ffoulkes-Jones, C.

Gürr, W.

McKechnie, N.M.

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TOXOPLASMOSE AND WEAL DWLAMMATION 
1421 
TOXOPLASMA GONDII-SPECIFIC T CELL CLONES ISOLATED 
FROM THE VITREOUS FLUID OF PATIENTS WITH RECURRENT 
OCULAR TOXOPLASMOSIS 
FERON EJ’-‘. VERJANS GMGM’. KLAREN VNA*. 
VAN DOORNIK CEM2. LUYENDIJK L’. AND KIJLSTRA A’. 
1 The Rotterdam Eye Hospital, Rotterdam (Netherlands). 
’ The Netherlands Ophthalmic Research Institute, Amsterdam 
Puroose Recurrent ocular toxoplasmosis is a major cause of 
blindness throughout the world. However, the pathogenetic 
mechanisms of reactivation of latent Toxoplasma gondii (T. gondii) 
infections are still unknqwn. An important question is whether the 
recurrent focal inflammatory responses in the retina are primarily 
directed against the parasite itself or whether autoimmune 
mechanisms play a role in the reactivations. 
Methods We designed a study to isolate and characterise the 
intraocular T cells involved in the recurrent inflammations. We 
tested a panel of T cell lines and T cell clones (TLCs) that have 
been derived from the vitreous of 7 patients with active recurrent 
ocular toxoplasmosis. 
w While no reactivity was found against retinal antigens, 
all T cell lines and 52 TLCs generated responded significantly to 
T. go&ii. The T. gondii-specific TLCs had the CD4+ phenotype, 
were generally HLA-DR restricted and displayed a heterogeneous 
T cell receptor usage. 
Conclusions Our findings suggest that the intraocular cellular 
immune response in recurrent ocular toxoplasmosis is predominant- 
ly T. gondii-specific. These observations are relevant not only to a 
further understanding of protective immunity and immunopatholo- 
gy but also may have implications for the design of effective 
vaccines. 
1422 
OCULAR TOXOPLASMOSIS AFTER ME POURTH DECADE. 
LABALEITE P.‘, KDWIER B.*, COIGNARD C.* and ROULAND J-F. ’ 
lDcpartmcot of Opbtbtmobgy, CRRU Lib, 59037 LSk mkx, Fmn. 
2Dcpmtim~t d F’amsitdo8y, CARU Litk, 59037 Ltlle ccdex, Frmce. 
m Toxoplasma retinocbomidhis remain the most prevalat form of infenious 
posterior uveitis in immunowmpetenl you”8 adults but is umwmmo” &a the age of SO 
This emity is often misdiagnosed due to the older a8e of patients 81 presentation. We 
rmiwd ten recma cases with positive laboramry tests for intraocular samples and analysed 
the clinical faturn of these unusual forms of ocular toxoplammsis 
m Ten patients, with a8e rm8ed between 50 and 87 years old (m = 65). were 
inch&d in this stud” during Ihe cericd f&rum-v 92-actcber 94 All oresfated a severe 
ih uvcitis 2) the iims between clinical onset of the hisease and ant&r char&r 
p-t&s 3) the w&is grade 4) the existewe of a retinociwmidal scar 5) the size of the 
active rainc&oroiditis lesion 6) the ~resexe of a ~ostaior vitrcas detachmenr and 7) the 
received treatment. 
s Ah topical anesthesia, an anterior plncmtesis WBS paformed by taking 0 I5 to 
0.30 ml of aauaus humor. At the same fimc a semlwical kst was achieved. Samples were 
immediately &ased at the Parasitdogy lnboratq of CHRU de Lille. The PCR lkcedure 
used chem&mincrcna probing of the Bl gene of Toxoplama gondii. The se@nenl used 
for the ampliticatioa cmrespond~cd to nucle&es 694 to 887 The procedure allowed the 
dacction of 0. I T gondii per sample Amlysis for @tic Mtibodies included 18’3, IgM and 
lg.4 isotypm (Enq@mW Toxoplasmosis ISC. R&ring Germany / ISAgA-M. bioM&iam, 
Fm”a / ISAgA-A, CHRU de till? Fmnw). 
&#J@ In our s&s tk me of pients wifh positive PCR for imraocula samples was 60 
% In& I@3 synthesis, kg.4 w IgM detection dhved us to obtain a positive diagnosis 
in the IO cases For all umples, two or - of the teclmiqwes were positive. Our clinical 
eMmilutiwshowedsome~~ticukrrcatum.thelonglimcb*wandinicJonsn~ 
ocular paracatais, the sevmity of intraocular i”tlmmukm, the big size of the 
retinwhoroidifis lesion and the presace of a posterior viweoua detachment 
m Confirmation of the toxoplasma origin was obtained in all the ten uveitis cases 
by -on of FCR md semlogical tests. Local conditions favorking the diffision of 
parasitic mataial may explain the l&h rate of positive reuh for PCR. This series shows 
- clinical feahues fhat may encompass this oflen misdiagnosed form of ocular 
toxoplasmosis 
1423 
Association of IgG and IgE antibodies detection for the diagnosis 
of Toxocariosis 
PICDT S. 1 ; MOSSUZ V., ; GONZALVEZ B. 2 ; MOUl‘LON M. 2 ; AMBSD,S& 
THOMAS P. 1 
1 - Departement de ParasitologieMycologie Medicale et Mokulaire CNRS UP 
78. Grenoble - France 
2 - Service d’Ophab”ologk - MU de Grenoble - BP 217 X - 38043 Grenoble Cedex 
- France 
Purpose : Clinical examination is poorly infomutive for the diagnosis of ocular 
and visceral toxocariosis. Various serological tests are available, but “one of 
them provide definitive confirmation of the diagnosis. We propose to evaluate 
specific IgG and IgE and to correlate these data with clinical presentation and 
evolutio” of patients with long lasting follow up. 
Methods : Serum from 11 patients suffering visceral or ocular toxocariosis, based 
on epidemiological, clinical and therapeute consideration, were collected and 
stored frozen. Serum from normal individuals or patients suffering other 
infeaious diseases were cc&&d in the same conditions. 
Semidiagnosis was performed by immunoenzymatic way “sing antigen from 
Toxocara canis larvae stage to determine specific IgG and IgE levels. Data were 
exmesd as tox~can units obtained bv correction of the valve of ontic dens&-v of 
the sample go with a calculated index factor. 
Results : When data from I,zG and IeE assays were oluaed on the same maoh. we 
observed that all the eleven greatly~proIx&le to&&is were confir& &IgG 
and IgE data over cut-off valves. None of the others patients presented a 
positive combined serological test. 
Conclusion : We suggest that diagnosis of toxocariosis could be greatly enhanced 
by the conmmittent determination of IgG and IgE anti-toxocara canis antibodies. 
A positive IgG only, is in favour of a” infection in the past while a positivity of 
both IgG and IgE is in favour of a in progress infection. Experiments are actually 
performed to evaluate the use~llness of such analysis on aqueous humor samples 
during ocular toxocariosis. 
1424 
‘I-HE ROLE OF IMMUNOLOGICALLY CROSS-REACTIVE ANTIGENS IN THE 
DEVELOPMENT OF OCULAR ONCHGCERCIASIS 
BRAUN G., MCKECHNE N.M., GURR W. AND C. FFOULKESJONES 
Dqmrtment of Pathology, University of Cambridge, LX 
Purpose: Our primary objective is the study of mechanisms involved 
in the development of posterior segmemt pathology in onchocerciasis. 
Based on the observation of immunological cross-reactivity we 
suggest that structural similarities between a host ocular antigen and 
an antigen of Onchocerca wloulus may have a role in the initiation of 
autoimmune reactivitv. 
Methods: The cros&eactive antigens, designated 0~39 and hr44, 
derived from0. wloulus and human retina resuectivelv. have been 
cloned and their piimary structures compare%. For the 
characterisation of the cross-reactivity, monodonal antibodies to these 
antigens have been prepared and T cell lines established. The 
recombinant antigens have also been used to study the potential to 
induce disease in the Lewis rat. 
Results: Primary structure analysis showed limited sequence 
identities, confined to small peptides, between the antigens Ov39 and 
hr44 and 0x09 and visual rhodopsin. A monoclonal antibody raised 
to 0~39 is aoss-reactive with hr44 and gave evidence for a shared 
conformational epitope. Hr44 and Ov39 also share T cell cross- 
reactivity. Hr44 is a neurospecific, membrane associated class I 
antigen and localises in those tissues affected by ocular onchocerciasis. 
Like some other self-antigens, hr44 induces ocular disease in the 
Lewis rat, however, the histopathology appears to differ from all the 
other autoimmune uveitis models. 
Conclusions: These findings suggest a potential mechanism for an 
autoimmune etiology of uveitis in ocular onchocerciasis. 
Tbir research is supported by the British Medical Resarch Cauncll, The Wellcome Trust 
Foundatim,, the Smss National Fends, the Royal society and the European Cmnmu”ity. 
s77 


1424 The role of immunologically cross-reactive antigens in the development of ocular onchocerciasis 

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1424 The role of immunologically cross-reactive antigens in the development of ocular onchocerciasis

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