A case of clinically amyopathic dermatomyositis that was refractory to intensive immunosuppressive therapy including tofacitinib, but successfully treated with plasma exchange therapy.

Clinically amyopathic dermatomyositis (CADM) patients often develop rapidly progressive interstitial lung disease (RP-ILD). A high level of anti-melanoma differentiation-associated gene 5 antibodies (anti-MDA5 Ab) before treatment is associated with RP-ILD development, a poor treatment response, and poor survival. The prognosis of CADM patients remains poor due to ILD even with combined intensive immunosuppressive therapy. Recently, several additional therapies, including tofacitinib (TOF) and plasma exchange (PE) therapy, have been reported to be effective. We herein report a case of CADM-ILD with a high level of anti-MDA5 Ab that was refractory to combined intensive immunosuppressive therapy including TOF, but successfully treated with PE. The following are possible reasons why TOF was ineffective: (1) cytokines that were not suppressed by TOF played an important role in RP-ILD; (2) TOF was administered later than previously reported; and (3) TOF did not suppress pathological substances such as antibodies. On the other hand, PE removes cytokines and various pathological substances. Therefore, PE may be a more reasonable additional therapy for intractable CADM-ILD.

Usefulness of tissue inhibitor of metalloproteinase 1 as a predictor of sustained remission in patients with antineutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: We previously identified tissue inhibitor of metalloproteinase 1 (TIMP-1) as a biomarker of disease activity that distinguished mildly or highly active antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) from remission 6 months after the initiation of remission-induction therapy. In the present study, we investigated whether TIMP-1 is clinically useful as a predictor of relapse and sustained remission in AAV patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) during maintenance therapy. METHODS: The relationship between serum TIMP-1 levels and clinical outcomes in AAV patients receiving maintenance therapy was assessed using the follow-up data of a Japanese large-cohort study (the RemIT-JAV-RPGN study) and data collected from AAV patients on maintenance therapy in our hospital (the MAAV-EU study). RESULTS: In the RemIT-JAV RPGN study, serum levels of TIMP-1 were significantly higher in mildly active AAV patients with MPA and GPA 6 months after the initiation of remission-induction therapy than in patients in remission. Regarding maintenance therapy, elevated levels of TIMP-1 in patients in remission were associated with relapse and/or difficulty reducing the glucocorticoid dosage after 6 to 12 months. In the MAAV-EU study, serum levels of TIMP-1 were elevated in relapsed patients 6 months before relapse, earlier than the increase in serum levels of CRP. Analyses of both studies revealed that approximately 30% of patients in remission with a serum TIMP-1 level ≥ 150 ng/mL relapsed after 6 to 12 months, while the majority of patients with a TIMP-1 level < 150 ng/mL sustained remission for at least 12 months. CONCLUSION: We herein demonstrated that TIMP-1 is more useful as a predictive biomarker of sustained remission than as a predictor of relapse in maintenance therapy for AAV. TIMP-1 levels < 150 ng/mL are important for the long-term maintenance of remission and may be an indicator for the tapering or cessation of treatment.

Giant Cell Arteritis Presenting with Ptosis and Diplopia.

Giant cell arteritis (GCA) is vasculitis of large-sized vessels that can lead to vision loss. We herein report a rare case of GCA accompanied by ptosis and diplopia as early symptoms, which were caused by third nerve palsy. A 78-year-old man presented with fever, right temporal headache, right eyelid ptosis, and diplopia. GCA was confirmed by a temporal artery biopsy. The symptoms disappeared after a slight delay following the administration of prednisolone. Unlike vision loss, ptosis and diplopia are considered to be reversible and responsive to treatment. GCA should not be ruled out if patients exhibit these ophthalmic symptoms.

The association between ear involvement and clinical features and prognosis in ANCA-associated vasculitis.

OBJECTIVE: The concept of otitis media with ANCA-associated vasculitis (OMAAV) was recently proposed by the study group of the Japan Otological Society. However, little is known about the effect of ear involvement on the clinical features and prognosis of AAV. We investigate this issue in this study. METHODS: We retrospectively examined 36 patients diagnosed with OMAAV and 44 patients diagnosed with AAV without ear involvement (non-OMAAV) at Ehime University Hospital from 2013 to 2018. We collected serological findings including ANCA type and titer, C-reactive protein (CRP), serum creatinine level, organ involved at initial diagnosis, treatment, remission, disease relapse, and mortality from medical records. We investigated whether clinical features and outcomes differed between the OMAAV and non-OMAAV groups. RESULTS: Age, ANCA titer, and CRP at initial diagnosis were not significantly different between the two groups, and the rate of intravenous cyclophosphamide (IVCY) use also did not differ. The proportions of patients with concurrent eye involvement, facial palsy (FP), and hypertrophic pachymeningitis (HCP) were significantly higher in the OMAAV than in the non-OMAAV group (p = 0.005, 0.005 and 0.049, respectively), while both renal and peripheral nerve involvement were significantly less common in OMAAV patients (p = 0.04). Among the 30 patients with renal involvement, serum creatinine level at diagnosis was significantly lower in the OMAAV group (p = 0.04). The mortality rate was 8.3% in OMAAV and 6.8% in non-OMAAV cases, but this difference was not significant. The rate of relapse was 33.3% in OMAAV and 13.6% in non-OMAAV cases; this difference was significant (p = 0.04). CONCLUSIONS: Serological measurements of disease activity did not differ between the groups. Eye involvement, FP, and HCP, however, were significantly more common in AAV with ear involvement. In addition, renal involvement was less common and renal impairment was milder in AAV with ear involvement. These findings can be considered clinical features. The relapse rate was significantly higher in AAV with ear involvement.

The hearing prognosis of otitis media with ANCA-associated vasculitis.

OBJECTIVE: The concept of otitis media with ANCA-associated vasculitis (OMAAV) was recently proposed by the study group of the Japan Otological Society. However, information remains limited regarding the hearing outcome of OMAAV. Thus, we investigated this issue in this study. METHODS: We retrospectively examined 50 ears from 32 patients diagnosed with OMAAV at our hospital between 2010 and 2019. We collected the results of pure tone audiometry (PTA) at diagnosis and changes in PTA threshold after treatment, serological findings including ANCA type, titer, soluble interleukin-2 receptor (sIL2R), and C-reactive protein, organs involved at initial diagnosis, treatment, and disease relapse from medical records. According to the hearing outcome, patients were divided into two groups: good prognosis and poor prognosis groups. We investigated the clinical features, treatment, and changes in PTA between the groups. RESULTS: Age, sex, ANCA negativity, and the use of intravenous cyclophosphamide (IVCY) were significantly related to hearing prognosis of OMAAV, while other organs involved at diagnosis, serological findings, and relapse rate were not significantly associated with hearing outcome. Hearing level at diagnosis was significantly better in good prognosis group, while air-bone gap (ABG) was not significantly different between the groups. The air conduction (AC), bone conduction (BC), and ABG were significantly improved in the good prognosis group. However, ABG was not improved in the poor prognosis group, while AC and BC were significantly improved. The AC hearing level at diagnosis (58.5 dB) and hearing gain at 2 weeks after treatment (12.5 dB) were suggested as good indicators for predicting the hearing outcome of OMAAV. CONCLUSION: Younger age, male sex, shorter period from onset to diagnosis, the use of IVCY, and better hearing threshold at diagnosis were the good prognostic factors of the hearing outcome of OMAAV. These results suggest that earlier diagnosis of OMAAV might be needed for better hearing outcome, and the use of IVCY may be recommended for the treatment of OMAAV patients.

The treatment outcomes of rituximab for intractable otitis media with ANCA-associated vasculitis.

OBJECTIVE: To investigate treatment outcomes, hearing outcomes, and adverse effects of rituximab (RTX) for intractable otitis media with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (OMAAV). METHODS: Twenty-three patients who met the criteria proposed by the OMAAV study group were included. RTX was used for patients who had difficulty achieving induction of remission using glucocorticoids (GC) and intravenous cyclophosphamide (IVCY). RESULTS: Six patients were treated with RTX (RTX group), while 17 patients did not require RTX for induction of remission (non-RTX group). All six patients in the RTX group achieved remission. Age, sex, and months from onset to diagnosis did not differ significantly between the groups. The air-conduction hearing thresholds at diagnosis and remission were 71.7±6.3dB and 50.1±5.1dB in the RTX group, and 56.8±4.8dB and 35.8±4.8dB in the non-RTX group, respectively. Hearing level at remission was significantly better in the non-RTX group (p<0.05), while hearing gain did not differ significantly between the groups. Infectious complications were similar between the groups. CONCLUSIONS: Our findings suggest that RTX is effective and safe for intractable OMAAV patients who have a poor response to GC and IVCY.

Targeted proteomics reveals promising biomarkers of disease activity and organ involvement in antineutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: Targeted proteomics, which involves quantitative analysis of targeted proteins using selected reaction monitoring (SRM) mass spectrometry, has emerged as a new methodology for discovery of clinical biomarkers. In this study, we used targeted serum proteomics to identify circulating biomarkers for prediction of disease activity and organ involvement in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS: A large-scale SRM assay targeting 135 biomarker candidates was established using a triple-quadrupole mass spectrometer coupled with nanoflow liquid chromatography. Target proteins in serum samples from patients in the active and remission (6 months after treatment) stages were quantified using the established assays. Identified marker candidates were further validated by enzyme-linked immunosorbent assay using serum samples (n = 169) collected in a large-cohort Japanese study (the RemIT-JAV-RPGN study). RESULTS: Our proteomic analysis identified the following proteins as biomarkers for discriminating patients with highly active AAV from those in remission or healthy control subjects: tenascin C (TNC), C-reactive protein (CRP), tissue inhibitor of metalloproteinase 1 (TIMP1), leucine-rich alpha-2-glycoprotein 1, S100A8/A9, CD93, matrix metalloproteinase 9, and transketolase (TKT). Of these, TIMP1 was the best-performing marker of disease activity, allowing distinction between mildly active AAV and remission. Moreover, in contrast to CRP, serum levels of TIMP1 in patients with active AAV were significantly higher than those in patients with infectious diseases. The serum levels of TKT and CD93 were higher in patients with renal involvement than in those without, and they predicted kidney outcome. The level of circulating TNC was elevated significantly in patients with lung infiltration. AAV severity was associated with markers reflecting organ involvement (TKT, CD93, and TNC) rather than inflammation. The eight markers and myeloperoxidase (MPO)-ANCA were clustered into three groups: MPO-ANCA, renal involvement (TKT and CD93), and inflammation (the other six markers). CONCLUSIONS: We have identified promising biomarkers of disease activity, disease severity, and organ involvement in AAV with a targeted proteomics approach using serum samples obtained from a large-cohort Japanese study. Especially, our analysis demonstrated the effectiveness of TIMP1 as a marker of AAV activity. In addition, we identified TKT and CD93 as novel markers for evaluation of renal involvement and kidney outcome in AAV.

Comparison of Localized and Systemic Otitis Media With ANCA-Associated Vasculitis.

OBJECTIVE: To investigate differences in immune activity based on the presence of multiple organ involvement in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and whether hearing outcomes are different between patients with AAV localized to the ear and patients with systemic AAV. STUDY DESIGN: Retrospective case review. SETTING: University hospital. PATIENTS: Twenty patients with otitis media with AAV (OMAAV) who met the criteria proposed by the OMAAV study group in Japan. MAIN OUTCOME MEASURE(S): Serum levels of C-reactive protein, ANCA titer, soluble interleukin-2 receptor levels, and hearing outcome. RESULTS: Thirteen patients had disease involvement of organs other than the ear (systemic OMAAV group); involvement was localized to the ear in seven patients (localized OMAAV group). Serum levels of C-reactive protein, ANCA titer, and soluble interleukin-2 receptor were not significantly different between the groups. Hearing levels at diagnosis and in remission were significantly worse in the localized OMAAV group compared with the systemic OMAAV group. Hearing gain was not significantly different between groups. CONCLUSION: It is suggested that immune activity in patients with AAV localized to the ear is equivalent to activity in patients with systemic AAV. Therefore, we may need treatment for OMAAV equal in intensity to that for systemic AAV. As the hearing level at diagnosis was worse in patients with AAV localized to the ear than in patients with systemic AAV, earlier diagnosis may be needed to improve hearing outcome.

T-cell Receptor Signaling Activates an ITK/NF-κB/GATA-3 axis in T-cell Lymphomas Facilitating Resistance to Chemotherapy.

Purpose: T-cell lymphomas are a molecularly heterogeneous group of non-Hodgkin lymphomas (NHL) that account for a disproportionate number of NHL disease-related deaths due to their inherent and acquired resistance to standard multiagent chemotherapy regimens. Despite their molecular heterogeneity and frequent loss of various T cell-specific receptors, the T-cell antigen receptor is retained in the majority of these lymphomas. As T-cell receptor (TCR) engagement activates a number of signaling pathways and transcription factors that regulate T-cell growth and survival, we examined the TCR's role in mediating resistance to chemotherapy.Experimental Design: Genetic and pharmacologic strategies were utilized to determine the contribution of tyrosine kinases and transcription factors activated in conventional T cells following TCR engagement in acquired chemotherapy resistance in primary T-cell lymphoma cells and patient-derived cell lines.Results: Here, we report that TCR signaling activates a signaling axis that includes ITK, NF-κB, and GATA-3 and promotes chemotherapy resistance.Conclusions: These observations have significant therapeutic implications, as pharmacologic inhibition of ITK prevented the activation of this signaling axis and overcame chemotherapy resistance. Clin Cancer Res; 23(10); 2506-15. ©2016 AACR.

Paraneoplastic pemphigus associated with fatal bronchiolitis obliterans and intractable mucosal erosions: Treatment with cyclosporin in addition to steroid, rituximab and intravenous immunoglobulin.

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease that presents as severe mucosal erosions and variable cutaneous lesions and is primarily associated with hematologically malignant or benign diseases. A 59-year-old Japanese woman presented with oral, ocular and vaginal mucosal erosions and erythema as well as blistering on her trunk and limbs. She developed bronchiolitis obliterans; lymphadenopathy in the cervical, subclavian, para-aortic and intraperitoneal regions; and splenomegaly. PNP with B-cell lymphoma was diagnosed. She was treated with two courses of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) for B-cell lymphoma, rituximab once every 3 weeks for five cycles, steroid pulse therapy, oral prednisolone, cyclosporin and high-dose i.v. immunoglobulin. The B-cell lymphoma was in remission after two courses of R-CHOP treatment. Although her skin erythema and blistering were also improved, the mucosal erosions and bronchiolitis obliterans gradually worsened. The patient died of bronchiolitis obliterans after 6 months of hospitalization. Because a cellular immune response is thought to be involved in the pathogenesis of PNP, cyclosporin therapy is expected to aid in suppressing the cellular response. In this case, however, the patient's mucosal lesions and bronchiolitis obliterans were not improved by regular administration of cyclosporin therapy.

Methotrexate-associated Lymphoproliferative Disease with Multiple Pulmonary Nodules in a Patient with Rheumatoid Arthritis.

Patients with rheumatoid arthritis (RA) treated with methotrexate (MTX) sometimes develop lymphoproliferative disease (LPD). MTX-associated LPD can affect nodal or extranodal sites, including the gastrointestinal tract, skin, lungs, kidneys and soft tissues, at almost equal frequency. However, it is very rare for MTX-associated LPD to manifest as multiple nodules in the lungs. We herein report the case of a RA patient who developed MTX-associated LPD with multiple pulmonary nodules during a 5-year course of MTX therapy.

Severe fever with thrombocytopenia syndrome mimicking intravascular lymphoma.

A 63-year-old woman was admitted to our hospital, because of a high fever and general malaise which had persisted for several days. Laboratory findings showed leucopenia, thrombocytopenia, and abnormal liver functions. A bone marrow smear revealed hemophagocytosis. Since a diagnosis of intravascular large B cell lymphoma was strongly suspected, a random skin biopsy was performed but revealed no evidence of malignant lymphoma. She was treated with steroids, blood product transfusions, and antibiotics, and then gradually recovered. The severe fever with thrombocytopenia syndrome (SFTS) viral genome was detected in her serum obtained in the acute phase. Therefore, the final diagnosis was SFTS, which is among the major causes of hemophagocytic syndrome.

Cytotoxic T lymphocyte lysis of HTLV-1 infected cells is limited by weak HBZ protein expression, but non-specifically enhanced on induction of Tax expression.

BACKGROUND: Immunogenetic evidence indicates that cytotoxic T lymphocytes (CTLs) specific for the weak CTL antigen HBZ limit HTLV-1 proviral load in vivo, whereas there is no clear relationship between the proviral load and the frequency of CTLs specific for the immunodominant antigen Tax. In vivo, circulating HTLV-1-infected cells express HBZ mRNA in contrast, Tax expression is typically low or undetectable. To elucidate the virus-suppressing potential of CTLs targeting HBZ, we compared the ability of HBZ- and Tax-specific CTLs to lyse naturally-infected cells, by co-incubating HBZ- and Tax-specific CTL clones with primary CD4(+) T cells from HLA-matched HTLV-1-infected donors. We quantified lysis of infected cells, and tested whether specific virus-induced host cell surface molecules determine the susceptibility of infected cells to CTL-mediated lysis. RESULTS: Primary infected cells upregulated HLA-A*02, ICAM-1, Fas and TRAIL-R1/2 in concert with Tax expression, forming efficient targets for both HTLV-1-specific CTLs and CTLs specific for an unrelated virus. We detected expression of HBZ mRNA (spliced isoform) in both Tax-expressing and non-expressing infected cells, and the HBZ26-34 epitope was processed and presented by cells transfected with an HBZ expression plasmid. However, when coincubated with primary cells, a high-avidity HBZ-specific CTL clone killed significantly fewer infected cells than were killed by a Tax-specific CTL clone. Finally, incubation with Tax- or HBZ-specific CTLs resulted in a significant decrease in the frequency of cells expressing high levels of HLA-A*02. CONCLUSIONS: HTLV-1 gene expression in primary CD4(+) T cells non-specifically increases susceptibility to CTL lysis. Despite the presence of HBZ spliced-isoform mRNA, HBZ epitope presentation by primary cells is significantly less efficient than that of Tax.

Protein kinase C inhibitor generates stable human tolerogenic dendritic cells.

Tolerogenic dendritic cells (DCs) are a promising tool for a specific form of cellular therapy whereby immunological tolerance can be induced in the context of transplantation and autoimmunity. From libraries of bioactive lipids, nuclear receptor ligands, and kinase inhibitors, we screened conventional protein kinase C inhibitors (PKCIs) bisindolylmaleimide I, Gö6983, and Ro32-0432 with strong tolerogenic potential. PKCI-treated human DCs were generated by subjecting them to a maturation process after differentiation of immature DCs. The PKCI-treated DCs had a semimature phenotype, showing high production of IL-10, and efficiently induced IL-10-producing T cells and functional Foxp3(+) regulatory T cells from naive CD4(+) T cells, thus eliciting a strong immunosuppressive function. They also showed CCR7 expression and sufficient capacity for migration toward CCR7 ligands. Additionally, PKCI-treated DCs were highly stable when exposed to inflammatory stimuli such as proinflammatory cytokines or LPS. Conventional PKCIs inhibited NF-κB activation of both the canonical and noncanonical pathways of DC maturation, thus suppressing the expression of costimulatory molecules and IL-12 production. High production of IL-10 in PKCI-treated DCs was due to not only an increase of intracellular cAMP, but also a synergistic effect of increased cAMP and NF-κB inhibition. Moreover, PKCI-treated mouse DCs that had properties similar to PKCI-treated human DCs prevented graft-versus-host disease in a murine model of acute graft-versus-host disease. Conventional PKCI-treated DCs may be useful for tolerance-inducing therapy, as they satisfy the required functional characteristics for clinical-grade tolerogenic DCs.

Activation of T-cell receptor signaling in peripheral T-cell lymphoma cells plays an important role in the development of lymphoma-associated hemophagocytosis.

Peripheral T-cell lymphoma (PTCL) is a biologically diverse lymphoid malignancy. The clinical aggressiveness associated with hemophagocytic syndrome (HS) is a characteristic of PTCL, being more distinctive in CD8(+) PTCL. However, the underlying mechanism of PTCL-associated HS has not yet been fully investigated. We newly established a novel IL-2-dependent CD8(+) PTCL lymphoma cell line (T8ML-1) from a patient with CD8(+) PTCL who suffered recurrent HS accompanying disease flare-up. Focusing on the lymphoma cell T-cell receptor (TCR), we examined the lymphoma cell functions responsible for such clinical manifestations. First, T8ML-1.1 in which endogenous TCR-α/ß chains were silenced by siRNAs, and T8ML-1.2 in which endogenous TCR-α/ß chains were replaced with HLA-A*24:02-restricted and WT1(235-243)-specific TCR-α/ß, were established. T8ML-1 exerted phytohemagglutinin (PHA)-dependent cytotoxicity via granular exocytosis. Additionally, soluble factors produced by PHA-stimulated T8ML-1, which included INF-γ and TNF-α, but not by simple-cultured T8ML-1, caused human monocytes to exhibit erythrophagocytosis and thrombophagocytosis in vitro. PHA binding induced phosphorylation of CD3ζ chain. Furthermore, both cytotoxicity and hemophagocytosis were completely inhibited by T8ML-1.1, but eventually restored by T8ML-1.2. These data suggest that exogenous activation of TCR signaling in PTCL cells might play an important role in the formation of PTCL-associated HS.

Subtypes of familial hemophagocytic lymphohistiocytosis in Japan based on genetic and functional analyses of cytotoxic T lymphocytes.

BACKGROUND: Familial hemophagocytic lymphohistiocytosis (FHL) is a rare disease of infancy or early childhood. To clarify the incidence and subtypes of FHL in Japan, we performed genetic and functional analyses of cytotoxic T lymphocytes (CTLs) in Japanese patients with FHL. DESIGN AND METHODS: Among the Japanese children with hemophagocytic lymphohistiocytosis (HLH) registered at our laboratory, those with more than one of the following findings were eligible for study entry under a diagnosis of FHL: positive for known genetic mutations, a family history of HLH, and impaired CTL-mediated cytotoxicity. Mutations of the newly identified causative gene for FHL5, STXBP2, and the cytotoxicity and degranulation activity of CTLs in FHL patients, were analyzed. RESULTS: Among 31 FHL patients who satisfied the above criteria, PRF1 mutation was detected in 17 (FHL2) and UNC13D mutation was in 10 (FHL3). In 2 other patients, 3 novel mutations of STXBP2 gene were confirmed (FHL5). Finally, the remaining 2 were classified as having FHL with unknown genetic mutations. In all FHL patients, CTL-mediated cytotoxicity was low or deficient, and degranulation activity was also low or absent except FHL2 patients. In 2 patients with unknown genetic mutations, the cytotoxicity and degranulation activity of CTLs appeared to be deficient in one patient and moderately impaired in the other. CONCLUSIONS: FHL can be diagnosed and classified on the basis of CTL-mediated cytotoxicity, degranulation activity, and genetic analysis. Based on the data obtained from functional analysis of CTLs, other unknown gene(s) responsible for FHL remain to be identified.

HLA class I binding of HBZ determines outcome in HTLV-1 infection.

CD8(+) T cells can exert both protective and harmful effects on the virus-infected host. However, there is no systematic method to identify the attributes of a protective CD8(+) T cell response. Here, we combine theory and experiment to identify and quantify the contribution of all HLA class I alleles to host protection against infection with a given pathogen. In 432 HTLV-1-infected individuals we show that individuals with HLA class I alleles that strongly bind the HTLV-1 protein HBZ had a lower proviral load and were more likely to be asymptomatic. We also show that in general, across all HTLV-1 proteins, CD8(+) T cell effectiveness is strongly determined by protein specificity and produce a ranked list of the proteins targeted by the most effective CD8(+) T cell response through to the least effective CD8(+) T cell response. We conclude that CD8(+) T cells play an important role in the control of HTLV-1 and that CD8(+) cells specific to HBZ, not the immunodominant protein Tax, are the most effective. We suggest that HBZ plays a central role in HTLV-1 persistence. This approach is applicable to all pathogens, even where data are sparse, to identify simultaneously the HLA Class I alleles and the epitopes responsible for a protective CD8(+) T cell response.