Segregation of type 1 cytokine production in human peripheral blood lymphocytes: phenotypic differences between IFN-gamma and IL-2-producing cells in the CD8+ T cell subset

Whole blood cytokine profiles in cats infected by feline coronavirus and healthy non-FCoV infected specific pathogen-free cats

In this study, the cytokine profiles of clinically healthy cats naturally infected with feline coronavirus (FCoV), of cats with feline infectious peritonitis (FIP) and of specific pathogen-free (SPF) cats were investigated in whole blood using a traditional reverse-transcriptase polymerase chain reaction (RT-PCR) assay and a semi-quantitative method of analysis based on computerised quantification of positive bands. The low inter-assay coefficient of variation recorded demonstrated that this method is highly repeatable. Compared with SPF cats, cytokine production was upregulated in most of the samples from FCoV-positive non-symptomatic cats. The appearance of a case of FIP in the cattery was associated with an increased expression of cytokines, in particular there was an increased production of IL-1beta and IFN-gamma, suggesting that these cytokines might protect infected cats from the disease. This hypothesis was also supported by the low levels of IFN-gamma recorded in blood from cats with FIP.

Detection of human perforin by ELISpot and ELISA: Ex vivo identification of virus-specific cells

The perforin (PFN) protein is essential for the elimination of target cells by cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. The study of cells releasing PFN has been hampered by a lack of sensitive methods. We therefore produced PFN-reactive monoclonal antibodies (mAb) and developed capture enzyme-linked immunosorbent (ELISA) and enzyme-linked immunospot (ELISpot) assays. Three mAbs were generated and shown to react with unique determinants of PFN. All mAbs recognized intracellular PFN in human peripheral blood mononuclear cell (PBMC) as assessed by flow cytometry and immunohistochemistry. Functional PFN capture ELISA and ELISpot assays were developed utilizing two of the mAbs for capture and the third mAb for detection. When examining PFN release by the YT lymphoma cell line, the ELISpot displayed a greater detection sensitivity than the ELISA. Assessment of PFN release by a CTL clone using ELISpot gave results consistent with a parallel (51)Cr-release cytotoxicity assay. Moreover, PFN release by PBMC could be quantified by ELISpot and ELISA after ex vivo stimulation with defined CTL epitopes from common viruses. These novel immunoassays will be valuable for further investigations of the mechanisms underlying granule-mediated apoptosis. In addition, the capture immunoassays could provide tools for studying CTL responses in infectious and tumor diseases as well as for vaccine development.

Tc1 effector diversity shows dissociated expression of granzyme B and interferon-gamma in HIV infection

OBJECTIVE

To examine antigen specific cytotoxic effector T cell diversity in HIV infected individuals.

DESIGN

We used a panel of previously defined HLA class I-restricted HIV peptides to stimulate CD8 cells in freshly isolated peripheral blood mononuclear cells of HIV infected patients, to determine cognate killing via the perforin-granzyme pathway and inflammation induced by secretion of interferon (IFN)-gamma.

METHODS

ELISPOT assays were used to measure the secretion of granzyme B (GzB) and IFN-gamma at single cell resolution.

RESULTS

In all nine patients only approximately 20% of the peptides triggered a canonical Tc1 response with simultaneous release of GzB and IFN-gamma. The majority of these peptides (approximately 80%) that elicited recall responses fell into the 'single positive' category with induction of either GzB or IFN-gamma alone. The GzB positive cells did not produce interleukin (IL)-4 or IL-5.

CONCLUSION

The GzB positive but IFN-gamma negative CD8 cells are programmed to induce apoptosis mediated killing without inflammation while the GzB negative and IFN-gamma positive CD8 cells could mediate inflammation without killing. This Tc1 CD8 effector cell diversity and the understanding of these differentiation mechanisms may enable the precise implementation and fine-tuning of fundamentally different defense strategies against HIV and other infections.

Methylisothiazolinones elicit increased production of both T helper (Th)1- and Th2-like cytokines by peripheral blood mononuclear cells from contact allergic individuals

BACKGROUND

Delayed-type hypersensitivity reactions to nickel (Ni2+) in humans are associated with increased production of both T helper (Th) 1- and Th2-like cytokines. Cytokine responses to the major group of contact allergens, i.e. organic compounds, have been less extensively studied. We have investigated here the cytokine production induced by a mixture of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI), the active ingredients in common preservatives that are capable of eliciting allergic contact dermatitis.

OBJECTIVE

To characterize the immune response induced by MCI/MI in terms of the production of Th1- and Th2-like cytokines in peripheral blood mononuclear cells (PBMC) from allergic and non-allergic subjects.

METHODS

Ten subjects with a history of contact allergy to MCI/MI and nine age-matched non-allergic volunteers participated. Their actual status was confirmed by patch testing. PBMC were cultured in the presence or absence of MCI/MI; cell proliferation was measured employing [3H]thymidine incorporation; and the number of cytokine-producing cells was determined using the enzyme-linked immunospot (ELISpot) assay and the levels of soluble cytokines in culture media by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

The proliferative response of PBMC to MCI/MI was significantly greater in the case of the allergic group than for the non-allergic group, as was the production of interleukin (IL)-2 and IL-13 (as determined by ELISpot and/or ELISA). PBMC from three of the allergic individuals with increased production of IL-2 and IL-13 responded to MCI/MI with elevated numbers of cells producing IL-4 and IL-5. The increases in the production of IL-2, IL-4, IL-5 and IL-13 were positively correlated.

CONCLUSION

MCI/MI elicited concomitant production of both Th1- and Th2-like cytokines by PBMC from subjects with contact allergy to these substances. This finding indicates that the organic compounds MCI/MI elicit a mixed Th1- and Th2-type of response, similar to that elicited by the metal ion Ni2+ in Ni2+-sensitized individuals.

CD8+CD28-T Lymphocytes from HIV-1-Infected Patients Secrete Factors That Induce Endothelial Cell Proliferation and Acquisition of Kaposi's Sarcoma Cell Features

Kaposi's sarcoma (KS) develops more frequently in human immunodeficiency virus type 1 (HIV-1)-infected patients. In this study, we report that molecules released by CD8(+)CD28(-) T lymphocytes from HIV-1-infected patients promote endothelial-cell (EC) growth and induce ECs to acquire spindle cell morphology and upregulation of intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular endothelial cell growth factor receptor-3 (VEGFR-3) (a typical feature of the KS cell phenotype). The effects observed on ECs cocultured with in vivo activated CD28(-) cells were partly reproduced when ECs were grown in medium containing interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). At concentrations similar to those found in the supernatant of in vivo activated CD28(-) cells, the two proinflammatory cytokines sustained EC growth and survival only when combined. We, therefore, conclude that CD28(-) T lymphocytes from HIV-1-infected patients exert their effect on ECs through a mechanism involving both IFN-gamma and TNF-alpha. This finding may have wide implications for our basic understanding of the immunopathology of KS.

Antigen-specific T cell response in infants after recombinant hepatitis B virus vaccination at birth: evaluation of T helper lymphocyte diversity

Recombinant hepatitis B virus antigen (rHBsAg)-specific CD4+ T cell clones (TCC) were isolated and expanded from the peripheral blood of nine children vaccinated at birth against the hepatitis B (HB) virus. Four of them responded with protective antibody production (responders), three subjects were unable to produce detectable antibody levels even after revaccination (nonresponders), and two infants produced antibodies only after revaccination (slow responders). TCC were then characterized for their ability to produce cytokines known to be important for T cell expansion (interleukin-2, IL-2) and/or effector functions (IL-4, IFN-gamma, IL-10). Results demonstrated that the frequency of rHBsAg-specific TCC in the samples of nonresponders was comparable to or higher than that in the samples of responders. Nevertheless, the majority of TCC obtained from responders or from slow responders before revaccination displayed the T helper 1 (T(H1))-dominant phenotype, while the majority of TCC obtained from nonresponders were nonpolarized T lymphocytes. After revaccination, the distribution of the different T(H) subsets in slow responders was heterogeneous. Overall, our present data suggest that an absence or delay in developing an rHBsAg-specific antibody response to vaccination is not associated with the capacity to generate an Ag-specific T cell response. However, compared to responders, nonresponding infants react to the rHBsAg vaccination with a reduced capacity to expand and differentiate toward polarized T(H) cells.

Longitudinal study of intracellular T cell cytokine production in infants compared to adults

Intracellular cytokine production in lymphocytes obtained longitudinally from 325 healthy infants aged 2-12 months was compared with adult lymphocytes using four-colour flow cytometry. Peripheral blood samples (180 microlitres) were stimulated with phorbol 12-myristate 13-acetate, ionomycin and brefeldin A to induce production and intracellular accumulation of cytokines. The method was validated by assessing reproducibility, repeatibility, ruggedness (i.e. fresh versus day-old blood samples), precision, linearity and sensitivity. Among infants, the number and percentage of T lymphocytes (helper/inducer T cell subsets and cytotoxic/suppressor T cell subsets) producing IFN-gamma (type 1) and IL4 (type 2) increased over the first year of life but remained significantly lower than levels found in adults. In both infants and adults more CD4- T cells than CD4+ T cells were induced to make IFN-gamma. Infant Th1/Th2 ratios revealed modest Th1-skewed (predominant) profiles compared to adults, which were 5-10 times higher. Infant Tc1/Tc2 ratios revealed Tc1-skewed responses which were equal to adult ratios by age 12 months. At 12 months infant Th2 responses were closer to adult levels than were Th1 cells. Intracellular cytokine detection by flow cytometry is a rapid, sensitive, rugged and precise method to characterize immune status changes over time.

Antigenicity and immunogenicity of allogeneic retinal transplants

The transplantation of neuronal cells and tissues represents a promising approach for the treatment of incurable neurodegenerative diseases. Indeed, it has been reported recently that retinal transplantation can rescue photoreceptor cells and delay age-related changes in various retinal layers in rodents. However, retinal grafts deteriorate progressively after placement in recipients' eyes. Here we investigated whether a host's immune response elicited toward the graft contributes to its deterioration. Using an ELISA spot assay, we measured T cell responses to retinal tissues placed in the vitreous cavity of syngeneic and allogeneic mice. We found that allogeneic retinas induced potent alloimmune responses mediated by T cells secreting type 1 cytokines (IFN-gamma and IL-2). No response was found in mice engrafted with syngeneic retinas. In addition, all syngeneic retinal grafts displayed no signs of tissue damage (at 55 days), while the majority of allogeneic retinas deteriorated as early as 12 days after placement. Next, we showed that anti-donor responses occurred within two phenotypically and functionally distinct T cell subsets: CD4+ T cells secreting IL-2 and CD8+ T cells producing IFN-gamma. Importantly, CD4+ T cells were necessary and sufficient to cause graft deterioration, while CD8+ T cells did not contribute to this process.

In vivo priming of CD4 T cells that produce interleukin (IL)-2 but not IL-4 or interferon (IFN)-gamma, and can subsequently differentiate into IL-4- or IFN-gamma-secreting cells

The differentiation of antigen-stimulated naive CD4 T cells into T helper (Th)1 or Th2 effector cells can be prevented in vitro by transforming growth factor (TGF)-beta and anti-interferon (IFN)-gamma. These cells proliferate and synthesize interleukin (IL)-2 but not IFN-gamma or IL-4, and can differentiate into either Th1 or Th2 cells. We have now used two-color Elispots to reveal substantial numbers of primed cells producing IL-2 but not IL-4 or IFN-gamma during the Th1- or Th2-biased immune responses induced by soluble proteins or with adjuvants. These cells were CD4(+)CD44(high) and were present during immediate and long-term immune responses of normal mice. Naive T cell receptor for antigen (TCR) transgenic (DO11.10) T cells were primed in vivo after adoptive transfer into normal hosts and FACS((R)) cloned under conditions that did not allow further differentiation. After clonal proliferation, aliquots of each clone were cultured in Th1- or Th2-inducing conditions. Many in vivo-primed cells were uncommitted, secreting IL-2 but not IL-4 or IFN-gamma at the first cloning step, but secreting either IL-4 or IFN-gamma after differentiation in the appropriate conditions. These in vivo-primed, uncommitted, IL-2-producing cells may constitute an expanded pool of antigen-specific cells that provide extra flexibility for immune responses by differentiating into Th1 or Th2 phenotypes later during the same or subsequent immune responses.

Role of CD4+ and CD8+ T cells in allorecognition: lessons from corneal transplantation

Corneal transplantation represents an interesting model to investigate the contribution of direct vs indirect Ag recognition pathways to the alloresponse. Corneal allografts are naturally devoid of MHC class II+ APCs. In addition, minor Ag-mismatched corneal grafts are more readily rejected than their MHC-mismatched counterparts. Accordingly, it has been hypothesized that these transplants do not trigger direct T cell alloresponse, but that donor Ags are presented by host APCs, i.e., in an indirect fashion. Here, we have determined the Ag specificity, frequency, and phenotype of T cells activated through direct and indirect pathways in BALB/c mice transplanted orthotopically with fully allogeneic C57BL/6 corneas. In this combination, only 60% of the corneas are rejected, while the remainder enjoy indefinite graft survival. In rejecting mice the T cell response was mediated by two T cell subsets: 1) CD4+ T cells that recognize alloantigens exclusively through indirect pathway and secrete IL-2, and 2) IFN-gamma-producing CD8+ T cells recognizing donor MHC in a direct fashion. Surprisingly, CD8+ T cells activated directly were not required for graft rejection. In nonrejecting mice, no T cell responses were detected. Strikingly, peripheral sensitization to allogeneic MHC molecules in these mice induced acute rejection of corneal grafts. We conclude that only CD4+ T cells activated via indirect allorecognition have the ability to reject allogeneic corneal grafts. Although alloreactive CD8+ T cells are activated via the direct pathway, they are not fully competent and cannot contribute to the rejection unless they receive an additional signal provided by professional APCs in the periphery.

Analysis of the costimulatory requirements for generating human virus-specific in vitro T helper and effector responses

The present study analyzes the role of CD28-B7-mediated costimulation during in vitro human peripheral blood memory T cell activation by influenza A virus. Inhibition studies using the B7-binding fusion protein CTLA4Ig and antibodies against CD80 and CD86 demonstrate that CTLA4Ig and anti-CD86 inhibited influenza-specific T cell proliferation, interleukin (IL)-2 and interferon (IFN)-gamma production, and generation of influenza-specific CD8+ CTL. The production of IL-10 and IL-18, which are known to modulate T cell immune responses, were not affected by blocking the CD28-B7 costimulatory pathway. Inhibition of diverse influenza-specific T cell functions could be reversed by the addition of exogenous IL-2 or IL-12 but not by the addition of IFN-gamma or IL-18. Although IL-2 is known to overcome CD28-B7 costimulatory requirements, this is the first report showing that exogenous IL-12 is able to bypass CD28-B7 costimulatory blockade induced by CTLA4Ig in vitro. The induction of IFN-gamma production with the recently described IFN-gamma inducing cytokine IL-18 was not detected. In conclusion, these results demonstrate that CD86 represents a major costimulatory signal for the activation of resting peripheral blood memory T cells with recall antigens. These observations may have important implications for the development of immunotherapeutic strategies in diverse immunodeficiency diseases as well as in tumor immunotherapy.

Functional heterogeneity of cytokines and cytolytic effector molecules in human CD8+ T lymphocytes

CD8(+) T cells use a number of effector mechanisms to protect the host against infection. We have studied human CD8(+) T cells specific for CMV pp65(495-503) epitope, or for staphylococcal enterotoxin B, for the expression patterns of five cytokines and cytolytic effector molecules before and after antigenic stimulation. Ex vivo, the cytolytic molecule granzyme B was detected in a majority of circulating CMV-specific CD8(+) T cells, whereas perforin was rarely expressed. Both were highly expressed after Ag-specific activation accompanied by CD45RO up-regulation. TNF-alpha, IFN gamma, and IL-2 were sequentially acquired on recognition of Ag, but surprisingly, only around half of the CMV-specific CD8(+) T cells responded to antigenic stimuli with production of any cytokine measured. A dominant population coexpressed TNF-alpha and IFN-gamma, and cells expressing TNF-alpha only, IFN-gamma only, or all three cytokines together also occurred at lower but clearly detectable frequencies. Interestingly, perforin expression and production of IFN-gamma and TNF-alpha in CD8(+) T cells responding to staphylococcal enterotoxin B appeared to be largely segregated, and no IL-2 was detected in perforin-positive cells. Together, these data indicate that human CD8(+) T cells can be functionally segregated in vivo and have implications for the understanding of human CD8(+) T cell differentiation and specialization and regulation of effector mechanisms.

Revisiting tolerance induced by autoantigen in incomplete Freund's adjuvant

Injection of autoantigens in IFA has been one of the most effective ways of preventing experimental, T cell-mediated, autoimmune disease in mice. The mechanism that underlies this protection has, however, remained controversial, with clonal deletion, induction of suppressor cells or of type 2 immunity being implicated at one time or another. Using high resolution enzyme-linked immunospot (ELISPOT) analysis, we have revisited this paradigm. As models of autoimmunity against sequestered and readily accessible autoantigens, we studied experimental allergic encephalomyelitis, induced by myelin oligodendrocyte glycoprotein, proteolipid protein, myelin basic protein, and renal tubular Ag-induced interstitial nephritis. We showed that the injection of each of these Ags in IFA was immunogenic and CD4 memory cells producing IL-2, IL-4, and IL-5, but essentially no IFN-gamma. IgG1, but not IgG2a, autoantibodies were produced. The engaged T cells were not classic Th2 cells in that IL-4 and IL-5 were produced by different cells. The IFA-induced violation of self tolerance, including the deposition of specific autoantibodies in the respective target organs, occurred in the absence of detectable pathology. Exhaustion of the pool of naive precursor cells was shown to be one mechanism of the IFA-induced tolerance. In addition, while the IFA-primed T cells acted as suppressor cells, in that they adoptively transferred disease protection, they did not interfere with the emergence of a type 1 T cell response in the adoptive host. Both active and passive tolerance mechanisms, therefore, contribute to autoantigen:IFA-induced protection from autoimmune disease.

Regulation of TCR-induced IFN-gamma release from islet-reactive non-obese diabetic CD8(+) T cells by prostaglandin E(2) receptor signaling

Prostaglandins (PG) are released during tissue injury and inflammation, and inhibit immune responses at many points. PG may be one of several factors that protect not only against injury-induced, but also spontaneous, organ-specific autoimmune disease. Here we show that the production of PGE(2), normally produced at a very low rate in islets of Langerhans, is significantly increased in inflamed islets of non-obese diabetic (NOD) mice. We investigated a possible role of PGE(2) in controlling TCR-dependent release of IFN-gamma from islet-reactive NOD CD8(+) T cells. PGE(2) inhibited anti-TCR antibody-triggered release of IFN-gamma from CD8(+) T cell clone 8D8 and from polyclonal cytotoxic T lymphocytes (CTL). Using receptor subtype selective agonists, we present evidence that the effect of PGE(2) is mediated by EP(2) and EP(4) receptors, both of which are coupled to an increase in intracellular cAMP production. The cAMP analogs 8-Br-cAMP and Sp-cAMPS mimic the effect of EP(2)/EP(4) receptor agonists, inhibiting TCR-triggered IFN-gamma release from NOD CD8(+) T cells in a dose-dependent manner. The inhibitory effect of PGE(2) was largely reversed by IL-2 added at the time of culture initiation and decreased with increasing strength of stimulation through the TCR. Resting CTL were more sensitive to PGE(2) than recently expanded CTL and NOD CD8(+) T cells remained insensitive to PGE(2) for a longer time than BALB/c cells. Our study suggests that PGE(2) may be part of a regulatory network that controls local activation of T cells and may play a role in the balance between the development of islet autoimmunity or maintenance of tolerance.

Direct visualization of cytokine-producing recall antigen-specific CD4 memory T cells in healthy individuals and HIV patients

We have used computer-assisted cytokine ELISA spot analysis to measure the frequencies, the type of cytokine, and the amount of cytokine produced by individual recall Ag-specific CD4 memory cells in freshly isolated blood. We studied the memory cells specific for tetanus toxoid and purified protein derivative in 18 healthy individuals and in 22 HIV-infected patients on highly active antiretroviral therapy (HAART). In healthy individuals, the frequency, cytokine signature, and cytokine production per cell of these memory cells were stable over time. Although it is presently unclear whether the maintenance of the memory T cell pool depends upon Ag persistence, cross-reactive Ag stimulation, or cytokine-driven bystander stimulations and expansions, our data strongly argue for a stable memory cell pool in healthy individuals. In HIV patients, however, the frequency of these memory cells was a function of the viral load. The decreased numbers of functional memory cells in patients with high viral loads might provide one mechanism behind the immunodeficient state. Although the cytokine output per cell was unaffected in most patients (20 of 24), in some patients (4 of 24) it was >100-fold reduced, which might provide an additional mechanism to account for the reduced immunocompetence of these patients. The ability to visualize directly and quantify the cytokine produced by the low frequency memory cells in freshly isolated blood that have been physiologically stimulated by Ag should aid comprehensive studies of the Ag-specific memory cell pool in vivo, in health and disease.

Single-cytokine-producing CD4 memory cells predominate in type 1 and type 2 immunity

The patterns of Ag-induced cytokine coexpression in normal, in vivo-primed CD4 memory T cells has remained controversial because the low frequency at which these cells occur has effectively prevented direct ex vivo measurements. We have overcome this limitation by using two-color cytokine enzyme-linked immunospot assays and computer-assisted image analysis. We found CD4 memory cells that simultaneously expressed IL-2, IL-3, IL-4, IL-5, and IFN-gamma to be rare (0-10%). This cytokine segregation was seen in adjuvant-induced type 1, type 2, and mixed immunity to OVA, in Leishmania infection regardless of the Ag dose used or how long after immunization the assay was performed. The data suggest that type 1 and type 2 immunity in vivo is not mediated by classic Th1 or Th2 cells but by single-cytokine-producing memory cells.

A transgenic mouse model to analyze CD8(+) effector T cell differentiation in vivo

Antigen-specific effector T cells are prerequisite to immune protection, but because of the lack of effector cell-specific markers, their generation and differentiation has been difficult to study. We report that effector cells are highly enriched in a T cell subset that can be specifically identified in transgenic (T-GFP) mice expressing green fluorescent protein (GFP) under control of the murine CD4 promoter and proximal enhancer. Consistent with previous studies of these transcriptional control elements, GFP was strongly and specifically expressed in nearly all resting and short-term activated CD4(+) and CD8(+) T cells. However, when T-GFP mice were challenged with vaccinia virus, allogeneic tumor cells, or staphylococcal enterotoxin A, the cytotoxic and IFN-gamma-producing T cells lost GFP expression. Upon T cell receptor (TCR) ligation by alphaCD3, sorted GFP(+) cells fluxed calcium and proliferated vigorously. In contrast, GFP(-) effector cells showed a diminished calcium flux and did not proliferate. Instead, they underwent apoptosis unless supplied with exogenous IL-2. By reverse transcription-PCR analysis, the GFP(-) cells up-regulated the pro-apoptotic molecule, Fas-L, and down-regulated gene expression of the proximal TCR signaling molecule, CD3zeta, and c-jun, a component of the AP-1 transcription factor. Thus, differential regulation of TCR signaling may explain the divergent responses of naïve and effector T cells to antigen stimulation.

Vaccination with different HSV-1 glycoproteins induces different patterns of ocular cytokine responses following HSV-1 challenge of vaccinated mice

We previously reported that vaccination of BALB/c mice with different baculovirus expressed HSV-1 glycoproteins induced varying degrees of protection against HSV-1 ocular challenge, ranging from complete protection to no protection, to exacerbation of eye disease. To correlate specific local immune responses with protection and exacerbation of corneal scarring, we examined immune cell infiltrates in the cornea after ocular HSV-1 challenge of vaccinated mice. Mice were vaccinated with gD, which completely protects against corneal scarring, gG, which produces no protection against corneal scarring, or gK, which exacerbates corneal scarring. Cryostat sections of cornea were taken at different times after challenge and examined for infiltrating cells containing IL-2, IL-4, IFN-gamma, IL-6, or TNF-alpha. No corneal infiltrates were seen before challenge or 1 day after ocular challenge in any groups. By days 3-7, many cells containing IL-4 and IFN-gamma, but few cells containing IL-2, had infiltrated into the corneas of gG or mock vaccinated mice. At the same times, many cells containing IL-2, but few cells containing IL-4 or IFN-gamma, were seen in the corneas of gD vaccinated mice. In contrast, the corneas of mice vaccinated with gK contained large amounts of IL-2, IFN-gamma, and IL-4. Our results suggest that: (1) corneas from gD vaccinated mice had no corneal disease and developed a response highly biased toward IL-2 responses; (2) corneas from gG or mock vaccinated eyes had significant corneal disease and developed a mostly IL-4 and IFN-gamma cytokine response; and (3) corneas from gK vaccinated mice had exacerbated corneal disease and developed strong IL-2, IL-4 and IFN-gamma cytokine responses.