Journal of Autoimmunity (1991) 4,113-124

Combined Anti-interleukin-2 Receptor and Low-dose Cyclosporine Therapy in Experimental Autoimmune Uveoretinitis

Makoto Higuchi, Tibor Diamantstein*, Rachel R. Caspi

Hisao Osawaf and

Laboratory of Immunology, National Eye Institute, NIH, Bethesda, USA, and *Institute of Immunology, Klinikum Steglitz, Free University of Berlin, Germany (Received 5 April and accepted 8 August 1990) The effect of combination treatment with anti-interleukin-2 (IL-2)receptor monoclonal antibody (ART18) and cyclosporine A (CsA) on the effector stage of experimental autoimmune uveoretinitis (EAU) was examined. Efferent-stage EAU was induced in Lewis rats by adoptive transfer of a T-helper cell line specific to retinal soluble antigen (SAg). Rats were treated with ART18 (0.5 mg/kg/day), low dose CsA (1.5 mg/kg/ day), or a combination of both. The results were compared to groups treated with high dose CsA (10 mg/kg/day) and to sham-treated animals, with respect to clinical and histological EAU, lymphocyte proliferative responses to SAg, and the ability to transfer EAU to secondary recipients. Ten-day combination therapy with ART18 and low-dose CsA was more effective than high-dose CsA and almost completely suppressed EAU development. ART18 as sole therapy was partially effective, and was better than low dose CsA as sole therapy. Splenocytes of protected animals did not transfer EAU to secondary recipients, while splenocytes of sham-treated controls did, suggesting that the number of uveitogenic lymphocytes in the treated host was reduced by the therapy. In contrast, this therapy was completely ineffective against EAU induced by active immunization. The possible reasons for this discrepancy between the two respective models of EAU are discussed.

Introduction

Experimental autoimmune uveoretinitis (EAU), induced in susceptible animals by immunization with the retinal soluble antigen (SAg), serves as a model for a Correspondence to: Rachel R. Caspi, PhD, Laboratory of Immunology, NIH Building 10, Room lON216, Bethesda, MD 20892, USA.

National Eye Institute,

113 0896-8411/91/010113+

12 $03.00/O

0 1991 Academic Press Limited

114 M. Higuchi et al.

number of sight-threatening ocular inflammations of presumed autoimmune nature in humans [ 1, 21. EAU is characterized by the presence of a delayed-type hypersensitivity response to SAg, resulting in irreversible damage to the retinal photoreceptor cells where the SAg is located. CD4+ T lymphocytes play a central role in EAU, and the complete pathological picture can be induced in naive syngeneic animals with adoptively transferred, SAg-specific T-cell lines [3, 41. Moreover, EAU can be successfully treated with cyclosporine A (CsA), which primarily targets T lymphocytes [5]. Following experimental studies in the model of EAU, human uveitis has been successfully treated with CsA [6]. However, the nephrotoxicity experienced at therapeutic doses of this drug has severely limited its long-term use [7]. In addition, although primarily a T-cell targeting drug, CsA suppresses equally T cells of all antigenic specificities, resulting in general, rather than specific, immunosuppression. Increasing the specificity of the therapy to target the actual lymphocytes involved in the autoimmune response, while minimizing the side effects, is an important goal in the development of immunotherapeutic strategies. In many organ-specific autoimmune disease models, high affinity interleukin-2 (IL-2) receptors (IL2R) appear to play an important role. Soluble IL2R are found in the serum in experimental as well as in human autoimmune diseases [&lo], and in some disease entities their level is correlated with disease activity. In EAU and in experimental autoimmune encephalomyelitis (EAE) disease can be adoptively transferred only by recently-activated T cells, where IL2R expression is maximal, but not by rested line cells, which express low levels of IL2R ([3], [ 1 l] and Caspi, unpublished). It has been suggested that proliferation of autoaggressive lymphocytes may be necessary for disease induction, since irradiated T-cell lines are unable to transfer disease ([12] and Caspi, unpublished). In view of the tight association between expression of IL2R by autopathogenic T cells and their pathogenicity, immunomodulation aimed at eliminating high-affinity IL2R-bearing T cells is an attractive clinical approach. Such an approach would be expected to act primarily on the activated autoaggressive T cells, while sparing resting T cells of other antigenic specificities. Indeed, in several experimental autoimmune disease models, therapy with monoclonal antibodies to the IL2R or with a chimeric IL2-toxin has already yielded encouraging results [8,13-171. The present study utilizes the Lewis rat model of EAU to evaluate the therapeutic efficacy of an IL2R-directed treatment with the ART18 monoclonal antibody 1181, and the efficacy of a combination treatment using ART18 together with a subtherapeutic dose of CsA, in comparison to ‘traditional’ high-dose CsA therapy. The parameters evaluated were induction of disease, as measured by time of onset, incidence and severity, as well as the persistence of SAg-specific uveitogenic lymphocytes in the treated host, as reflected by the presence of a cellular response to SAg in the spleen, and the ability to transfer disease to secondary, untreated, recipients. In order to mimic clinical circumstances, where patients present with established disease and circulating activated T lymphocytes, we decided to treat EAU in its efferent stage. As a model for efferent stage disease we used adoptive transfer of an autoimmune SAg-specific CD4+ lymphocyte Iine (ThS), and compared this to treatment of actively induced EAU, beginning at 7 days after immunization. Our results indicate that the former, but not the latter, model of efferent-stage ocular

Anti-IL2 receptor therapy in EAU autoimmunity can be successfully treated by a combined anti-IL2R CsA treatment strategy.

115

and low-dose

Materials and methods Animals

Male and female Lewis rats weighing 150 to 200 g (6 to 10 weeks of age) were purchased from Charles River, Raleigh, NC. Only male animals were used as recipients of adoptively transferred cells. Reagents

SAg was purified from bovine retinas as described by others [19]. Rat spleen concanavalin A (ConA) conditioned medium (SCM) was prepared as described [3] and ConA was neutralized with 0.1 M alpha-methyl mannoside (Sigma Chemical Co., St Louis, MO). Mouse anti-rat IL-2 receptor monoclonal antibody of the IgGl isotype (ART18) was derived from the hybridoma clone ART18 as described previously [18]. Ascites fluid obtained from mice bearing the ART18 hybridoma was used for experiments after dilution in phosphate bufFered saline (PBS). CsA (Sandoz, Basel, Switzerland) was dissolved in olive oil at concentrations of 3 mg/ml and 20 mg/ml, and injected intramuscularly. Induction

of EAU

by active immunization

Bovine SAg was emulsified (1: 1) in complete Freund’s adjuvant (DIFCO, Detroit, Mich.), supplemented with 2.5 mg/ml Mycobacterium tuber&oh H37RA (GIBCO, Detroit, MI); Twenty-five ltg of SAg in 0.1 ml of emulsion was divided between the two hind footpads. Induction

of EAU

by adoptive transfer

SAg-specific T helper lymphocyte line (ThS) was derived from draining lymph nodes of immunized Lewis rats, and was maintained in culture in supplemented RPM1 1640, by alternating cycles of stimulation with SAg and IL-2-dependent expansion as described [3], except that fetal calf serum was substituted for human serum. Before adoptive transfer, rested ThS (2 x lo5 cells/ml) were activated with 5 pg/ml of ConA in the presence of antigen-presenting cells (APC, 2 x lo6 cells/ml) for 60 h. The activated lymphoblasts were washed and injected intravenously into naive Lewis recipients. Animals received between 12 x lo6 and 17 x lo6 cells. Treatment

Animals were divided into five treatment groups as follows: (a) ART18; 0.5 mg/kg/ day, intraperitoneally; (b) Low dose CsA; 1.5 mg/kg/day, in 0.1 ml, intramuscularly; (c) Combination; ART18, intraperitoneally and low dose CsA, intramuscularly; (d) High dose CsA; 10 mg/kg/day, intramuscularly; (e) Sham-treated control; 0.1 ml

116 M. Higuchi et al.

of olive oil/day, intramuscularly, and 0.5 mg protein/kg/day of non-specific mouse ascites, intraperitoneally (ascitic fluid from pristained BALB/c mice injected intraperitoneally with SP2/0 myeloma cells. Cedarlane Labs, Hornby, Ontario, Canada). Assessment of disease

Clinical disease was measured as incidence and time of onset of anterior chamber inflammation. Eyes were examined every day starting on day 2 after adoptive transfer or day 7 after active immunization, and disease was scored on a scale of 0 to 4, according to the intensity of anterior chamber inflammation. Grading was as follows: 0, no visible change; 1, minimal change (dilatation of iris and conjunctival blood vessels); 2, moderate (cloudy media); 3, marked (loss of red reflex, obscured pupil); 4, severe (loss of red reflex, hemorrhage, proptosis). Histological disease was measured as incidence and severity of posterior segment inflammation and retinal damage. Enucleated eyes were prefixed in 4% phosphate-buffered glutaraldehyde for 1 h, postfixed in 10% formaldehyde overnight, and embedded in paraffin. Six sections per eye (4 u in thickness) were cut at different depths along the antero-posterior plane of the eye through the posterior pole in the optic nerve area and stained with haematoxylin-eosin. Slides were evaluated in a masked fashion by an independent observer, and graded on a scale of 0 to 4 in half-point increments. 0, no change; 0.5, inflammatory cell infiltration of the retina, with or without photoreceptor damage, in less than l/4 of the retinal section area (ret. s.a.); 1, photoreceptor outer segment damage in 2 l/4 of ret. s.a.; 2, lesion extending to the outer nuclear layer and in 2 l/4 of ret. s.a.; 3, lesion extending to the inner nuclear layer and in 2 l/4 of ret. s.a.; 4, full thickness retinal damage in 2 l/4 ret. s.a. Mean grade of EAU in each group was calculated by averaging all eyes of EAU-positive rats. Quantitation

of serum antibodies by enzyme-linked

immunosorbent

assay (ELISA)

Blood was taken from ART18/low dose CsA-treated rats at various times after the beginning of treatment. Sera were separated and stored at - 20°C. Antibody titers against SAg were measured essentially as described [20]. Serum antibody titers against mouse Ig were measured as follows: microtitration plates were coated with 300 ng of mouse Ig (Jackson Immunoresearch Laboratories, Inc., West Grove, PA) in 100 ~1 of carbonate coating buffer/well and incubated for 4 h at 37°C. Serial dilutions of test sera were prepared in 100 ~1 of PBS with 0.05% Tween 20 and 0.5% bovine serum albumin (BSA) added to the wells and incubated for 2 h at 37°C. One hundred ul of diluted (1: 1,000) peroxidase-conjugated goat-anti rat IgG (Kirkegaard and Perry Laboratories, Gaithersburg, MD) which had been exhaustively absorbed with solid-phase mouse Ig (see below) was added, and the plates were incubated for 1 h at 37°C. One hundred ul of freshly prepared substrate buffer containing 0.04% o-phenylene-diamine and 0.0 15 o/0hydrogen peroxide was added and incubated for 40 s to 1 min, and the reaction was stopped with 50 ul of 4~ H,SO,. Samples were read at 490 nm with a LKB Minireader II. Antibody titers are expressed as ODdg, at serum dilution 1:20. Absorption of the goat anti-rat IgG with mouse Ig was done by incubating 2 ml of mouse IgG-Agarose (Jackson Immunoresearch Laboratories, Inc., West Grove, PA)

Anti-IL2 receptor therapy in EAU

117

with 1 ml of the peroxidase-conjugated goat anti-rat Ig diluted 1:lO in PBS for 30 min at room temperature on a rocking platform. Inhibition of in vitro proliferation of ThS cells by AR T18 Inhibition of ILZdependent proliferation ThS cells were used immediately after a 60-h stimulation with SAg on APC. Triplicate 0.2 ml cultures were set up by adding 2 x lo4 cells in 0.1 ml, to 0.1 ml of medium containing double dilutions of ART18 antibody or non-specific control ascites. SCM as a source of IL2 was added to each well in 10 ~1 to the final concentration of 5%. Cells were incubated, labelled with [3H]thymidine and harvested, as below. Inhibition of antigen-driven or mitogen-driven proliferation ThS cells were used after 2 weeks of rest in IL2-containing medium. Cultures of 2 x lo4 cells/well and 4 x lo5 AK/well were set up in the presence of ART18 or control ascites, as above. SAg or Con A was added to each well in 10 1(1to the final concentration of 10 ug/ml or 5 ug/ml respectively. Cultures were incubated, labelled and harvested as below. Lymph node cell and spleen cell responses to SAg Proliferative responses of spleen cells (from adoptively transferred animals) or draining lymph node cells (from actively immunized animals) to SAg were determined in triplicate 0.2 ml cultures in 96-well flat-bottom plates. Cultures of 2 x lo5 to 4 x lo5 cells were set up in supplemented RPM1 1640 medium [3] containing 1.5% normal rat serum, in the presence of 10 ug/ml of SAg, and were incubated for a total of 64 h. The cells were pulsed with 1 l.Ki[3H]thymidine (t3H]TdR) per well for the last 16 h of culture. Cultures were harvested on an automatic cell harvester (PhD, Cambridge Technology, Cambridge, MA) and read by standard liquid scintillation counting.

Serial transfer of lymphocytes from treated rats to naive rats Spleen cells from rats adoptively transferred with ThS cells (primary recipients) were depleted of excess macrophages by adherence to plastic and were cultured at the concentration of 2 x 106/ml with 5 ug/ml of ConA for 60 h. Cultured cells were washed and injected intravenously into naive rats (secondary recipients). Clinical examination of the secondary recipients was performed daily. Enucleated eyes were examined histopathologically, and lymphocyte responses to SAg were tested as in primary recipient donor rats. Presentation of results Experiments were repeated at least three times. Results are shown as averages of several experiments, or as representatives.

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M. Higuchi et al.

60 50

1000

10000

ART18 (I/dilution)

Figure 1. Inhibitory effect of ART18 on in vitro proliferation of uveitogenic ThS cells. Results are expressed as percent inhibition of response in comparison to control containing the same dilution of nonspecific control ascites. --A---, ConA; -O--, SAg; -W--, IL2.

Results ART18

inhibits activation and the subsequent ILZdependent

expansion of ThS cells

Inhibition of the proliferation of the ThS cell line in vitro by ART18 is shown in Figure 1. Proliferation with antigen and mitogen, which involve de novo generation of IL2R, were suppressed by ART18 in a dose-dependent manner. Suppression of IL-2 dependent proliferation was much more efficient than suppression of antigen or mitogen-driven proliferation, and was also dose-dependent. The reason for this difference in the efficiency of inhibition is not known, but may reflect a higher rate of synthesis of IL2R molecules in the presence of a direct antigenic (or mitogenic) stimulus. These in vitro results show that ART18 can directly suppress proliferation of IL2R-bearing ThS cells. Serum antibodies in AR Tl&treated

rats to mouse Ig

To determine the kinetics of the appearance of anti-mouse Ig antibodies in the sera of the treated animals, rats were continuously treated with ART18/low dose CsA, or with non-specific ascites and olive oil. Blood was collected at timed intervals, and the titer of anti-mouse Ig was determined by ELISA as described in Materials and Methods. Antibodies to the mouse Ig became detectable on day 7, and titers increased through day 18 (termination of experiment). Antibody titers rose more slowly in the treated animals, but reached control levels after 18 days of treatment (Figure 2). In subsequent experiments involving treatment of adoptively transferred recipients, the duration of therapy was limited to 10 days, since after that time significant titers of serum antibodies to the treatment mouse Ig were detectable. In vivo treatment of adoptively transferred

recipients

Groups of animals were treated with ART18 alone, low dose CsA alone, or their combination. Clinical disease (measured as incidence and time of onset of anterior

Anti-IL2 receptor therapy in EAU

4

6

8

IO

12

14

119

1

16

18

Days under treatment

Figure 2. Kinetics of appearance of anti-mouse Ig antibodiesin rats treated with ART18 plus low-dose CsA, in comparisonto sham-treatedanimals.-0--, ART18/CsA; -•--, non-specificcontrol ascites.

Table 1. Suppressive effect of combination treatment with AR T18 and low-dose CsA on

induction of EAU by adoptive transfer of ThS cells

Treatment ART18 CsA (1.5 mg/kg) Combination Sham treated CsA (10 mg/kg)

Total number of animals

Number of clinically positive (%)

14 14 14 19 14

8 (57) 13 (93) 1 (7) 17 (90) 6 (43)

Number of Average day positive by of onset histopathology (%) (*SE) 7.8 (-40.7) 7.1 (kO.4) 7.0(40) 5.9 (-&OS) 6.7 (kO.8)

9 14 5 18 12

(64) (100) (36) (95) (86)

‘Calculation based on histopathology of EAU-positive animals (if EAU included). SE: Standard error of the mean. Results represent a composite of three separate experiments.

Average EAU grade ( + SE)’ 2.1(+0.4) 2.0 (40.2) 0.8 (f0.3) 3.1 (k0.3) 1.3 (rtO.2)

is unilateral,

both eyes

chamber inflammation) as well as histological disease (measured as incidence and severity of posterior segment inflammation and retinal damage) were compared to sham-treated animals and to animals treated with high-dose CsA (Table 1). All disease parameters in the combination treatment group were strongly suppressed in comparison to all other groups, including the high-dose CsA group. Only one animal out of 14 given the combination treatment showed clinical evidence of disease, which was in keeping with the reduced incidence and EAU severity seen by histopathology. ART18 and low-dose CsA separately only partially suppressed disease, with the ART18 group showing lower incidence than the low-dose CsA. Spleen ceil responses to SAg Spleens from treated animals were collected 10 days after adoptive transfer of ThS cells, pooled within each group, and proliferative responses to SAg were measured by

120 M. Hiauchi et al.

CsA (IO)

ARTl8+

CsA( 1.5)

Cs A

(1.5)

ART18 0

20

I 40

I

Percent

,I,

I 60

I i 80

I

I,, 100

I2ro

of response

Figure 3. Proliferative responses of spleen cells from treated animals to SAg. Spleen cell response to SAg in the sham-treated control group was defined as 100%. Shown is the normalized average of three separate experiments + standard deviation.

thymidine uptake (Figure 3). Since responses to SAg in spleen cells of normal rats are essentially identical to background under these culture conditions (not shown), the level of response to SAg is considered to reflect the relative number of ThS cells in the tested spleens. The results show that spleen cells from rats receiving the combination treatment were essentially unable to respond to SAg. The level of response in splenocytes of rats receiving either treatment alone, or high dose CsA, was between 30% and 50% of that of sham-treated control rats. Thus, SAg responses in the recipient spleens closely followed the pattern of disease expression in the various treatment groups. Serial transfer of spleen cells from treated primary recipients of ThS cells to untreated secondary recipients Spleens collected from rats in the various treatment groups were cultured individually for 3 days with ConA and transferred to secondary recipients, so that each secondary recipient received the spleen of one individual donor. Only donors who themselves had EAU could transfer the disease to secondary recipients (Table 2). Disease in the secondary recipients was typically milder than in the respective donors, probably reflecting the fact that only a part of the originally transferred ThS cells were found in the donor spleen. Secondary recipients whose donors had milder EAU did not develop disease, resulting in a comparatively reduced incidence as a group. About half of the secondary recipients of spleen cells from rats given ART1 8 alone, low dose CsA alone or sham treatment developed EAU, while spleens from donors given the combination treatment or high dose CsA were unable to transfer disease. AR T18ICsA treatment

ofdisease induced by active immunization

Groups of Lewis rats were immunized with an emulsion of SAg in CFA and divided into the same treatment groups as previously. Treatment was started on day 7 after immunization and continued for 10 days. The 7-day time point was chosen ‘because the latent period of EAU induced by active immunization is 7 days longer than that

Anti-IL2 receptor therapy in EAU

121

Table 2. Combination treatment suppresses the ability of splenocytes from primary recipients of ThS cells to transfer EAU Incidence of EAU Treatment group ART18 CsA (1.5 mg/kg) Combination CsA (10 mg/kg) Sham treated

Primary recipients’

Secondary recipients’

415

215

515 215 315 13/13

215 O/5 O/5 6113

Secondary transfer rate2 0.5 0.4 0 0 0.46

‘Incidence of disease was determined by histopathological examination of enucleated eyes and is expressed as the number of positive/total animals in the group. ‘Transfer rate is calculated as the number of positive animals in the secondary recipient group, divided by the number of positive animals in the donor group.

of EAU induced by adoptive transfer, indicating that the generation of functional uveitogenic lymphocytes requires approximately 7 days [3]. We therefore consider this time point to represent a transition into the efferent stage of actively induced disease. In contrast to the dramatic effect of combination therapy and the ameliorating effect of ART18 alone on ThS-induced EAU, this therapy was completely ineffective in preventing EAU induced by active immunization. This held true even when treatment was started concurrently with immunization and continued for 18 days, covering both afferent and efferent phases. In fact, treatment with ART1 8 alone seemed to slightly, but reproducibly, aggravate the disease with respect to time of onset and incidence (data not shown). Low-dose CsA treatment and combination therapy had only a slight ameliorating effect. High-dose CsA completely or largely prevented disease (when started on day 0 or day 7, respectively), in keeping with previously published results [5]. Responses of draining lymph node cells to SAg and titers of anti-SAg antibodies in the serum of treated animals followed the same pattern as the expression of disease (not shown). Discussion This study explores the possibility of treating ocular autoimmunity in its efferent phase by targeting the activated uveitogenic T cells with a monoclonal antibody to the IL%R, with or without a concomitant treatment with low dose CsA. The results indicate that efferent stage EAU, as represented by the adoptive transfer of uveitogenic ThS cells, can be treated by the combination therapy with a high degree of success, and by ART18 alone with a moderate degree of success. The reduced an vitro responses to SAg of splenocytes from the treated animals, as well as their diminished ability to transfer EAU to secondary recipients, would suggest that there are fewer uveitogenic cells remaining in the spleens of animals protected by the Treatment. Hn contrast, the same combination treatment was completely ineflective in the therapy of EAU induced by active immunization. Treatment even with ART18

122 M. Higuchi et al.

alone seemed to slightly, but reproducibly, aggravate the disease, a result that was unexpected in view of previously published evidence that ART 18 therapy spares T suppressor cells [21]. The discrepancy between the results in the model of adoptive transfer compared to active immunization is striking, and similar dichotomy has also been reported in the treatment of EAE and of adjuvant arthritis by ART18 [8, 171. One could explain this apparent paradox by postulating differences in the cellular mechanisms operating during the efferent phase of these two respective EAU models. Indeed, while the number of adoptively transferred ThS cells is finite, in actively immunized animals recruitment of new clones may continue well into the efferent stage of disease, since antigen-containing emulsion is present at the injected site for many weeks. However, an alternative explanation could be provided by the mode of action of ART18. Since ART18 is a non-complement binding antibody (IgGl isotype) [18], it presumably does not cause cytotoxic elimination of the IL2Rexpressing lymphocytes it binds to, but rather acts by preventing their proliferation (although we cannot exclude some type of antibody-dependent cellular cytotoxicity). Experimental data suggest that autopathogenic cells may need to proliferate in the host to induce disease, since irradiated cells are ineffective ([12] and Caspi, unpublished). Our in vitro experiments showed that proliferation of ThS cells with IL2 was much more sensitive to suppression than proliferation in the presence of direct a.ntigenic/mitogenic stimulation. For obvious reasons, under conditions of adoptive transfer, the bulk of circulating ThS cells is not exposed to SAg, while in active immunization sustained antigenic stimulation continues throughout the treatment. Thus, an in vivo parallel to the situation observed in vitro might be involved in the ineffectiveness observed by us and by others in treatment of actively induced experimental autoimmunity by ART18. In line with this interpretation are the data of Roberge et al. [16], showing successful treatment of actively induced EAU by IL2-receptor-targeting therapy with the chimeric toxin IL2-PE40, which does cause elimination of its target cells. It is still entirely speculative which of the two models, adoptive transfer or active immunization in complete Freund’s adjuvant (CFA), better parallels the mechanisms operating in human disease. The two approaches to the targeting of IL2R-bearing cells, use of monoclonal antibodies to the light chain (55 kD) of the IL2R, and use of chimeric toxins where IL2 is coupled to a toxic moiety, such as a bacterial exotoxin, each has its merits and its drawbacks ([22], [23], and Lorberboum-Galski, personal communication). Chimeric IL2-toxins, utilizing the natural ligand of the IL2R, have an inherently higher afIinity of binding to the receptor, and the toxin moiety kills the target cell when the complex is internalized. However, the chimeric IL2-toxin has a short halflife in the serum and serious systemic side-effects, and bacterial toxins are highly immunogenic, resulting in production of antibodies against the therapeutic moiety. These properties effectively limit the possible duration of the treatment. Monoclonal antibodies have a lower afhnity of binding to the IL2R and are also immunogenic, and cytotoxic elimination of the target cells may be largely dependent on their isotype. However, they can be genetically engineered (‘humanized’) to largely overcome the latter two limitations and to make their potential half-life in the serum similar to that of normal immunoglobulins [22,23]. It is important to remember that these two approaches to IL2R-directed therapy are not necessarily mutually exclusive, but rather can constitute complementary treatment strategies.

Anti-IL2 receptor therapy in EAU

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In summary, our present results suggest that targeting of activated uveitogenic lymphocytes by monoclonal antibodies to the IL2R may be a viable strategy for treatment of some types of ocular autoimmunity. Use of ‘humanized’ monoclonal antibodies to IL2R should be explored as a useful adjunct to clinical treatment of uveitis with CsA, as well as to treatment with other, more traditional, forms of therapy.

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