Pre-transplant Soluble CD30 Is Associated With Bronchiolitis Obliterans Syndrome After Lung Transplantation

BACKGROUND

The purpose of this study was to determine the clinical relevance of soluble CD30 (sCD30) concentrations in sera from lung transplantation (LTx) candidates.

METHODS

Soluble CD30 concentrations were determined by enzyme-linked immunoassay in pre-transplantation sera of 38 LTx candidates and in serial samples taken after LTx from 10 patients.

RESULTS

LTx candidates did not have increased serum sCD30 concentrations when compared with healthy controls (mean +/- SE: 22.3 +/- 2.7 vs 26.2 +/- 3.4 U/ml). No relation could be found between age and serum sCD30 concentrations, neither in the pre-transplant patients nor in the healthy controls. In addition, no differences in sCD30 values could be detected between patients sorted by their original type of lung disease. Measurement of sCD30 in pre-transplant sera of LTx patients showed that the median concentration was 20 U/ml and that LTx patients with low sCD30 (< or = 20 U/ml) had a statistically significant (p = 0.039) longer period of freedom from bronchiolitis obliterans syndrome (BOS) compared to those with a high sCD30 concentration (> 20 U/ml). Furthermore, sCD30 concentrations in sera taken at several timepoints after LTx remained stable, although a peak could be observed before the clinical manifestation of acute rejection (AR).

CONCLUSIONS

Soluble CD30 before lung transplantation is significantly associated with an increased risk of BOS after transplantation.

Identification of HLA-A*0111N: a synonymous substitution, introducing an alternative splice site in exon 3, silenced the expression of an HLA-A allele

A new variant of the HLA-A*010101 allele designated as HLA-A*0111N, previously known as HLA-A*010101var, was identified in a patient requiring a stem-cell transplantation. The patient was typed by serologic methods as HLA-A2 homozygous and by sequence-based typing (SBT) as A*010101,020601. Flow-cytometric (FCM) analysis with 11 human monoclonal antibodies (mAbs) for the A1 molecule confirmed lack of any cell membrane expression of the A*0111N allele. One-dimensional isoelectric focusing (1D-IEF) of total cell lysate from the patient's cells revealed no cell surface and cytoplasmic A1 protein expression, whereas the HLA-A2 molecule was identified by both FCM analysis and 1D-IEF. DNA sequence analysis showed the presence of a synonymous substitution from G to T at position 597 in codon 175. RNA SBT revealed a deletion of 24 bp in exon 3, position 596 through 619, encoding codons 175 through 182 of the HLA-A*0111N allele. The synonymous substitution introduced a new splice site, resulting in an efficient splicing, because no classical A1 protein could be detected in the patient. This alternative splicing prevented the translation into a correct and stable class I molecule expression on the cell surface.

Tolerogenic immune responses to novel T-cell epitopes from heat-shock protein 60 in juvenile idiopathic arthritis

BACKGROUND

Juvenile idiopathic arthritis is a heterogeneous autoimmune disease characterised by chronic inflammation of one or more joints. In patients with this disease, T-cell reactivity to autologous heat-shock protein 60 (HSP60) is associated with a favourable prognosis. We sought to identify HSP60 T-cell epitopes to find potential targets for HSP60 immunotherapy and to assess whether immune responses to these epitopes contribute to the distinct clinical outcome of this disease.

METHODS

We identified eight potential epitopes using a computer algorithm from both self and microbial HSP60 binding to many HLA-DR molecules. We analysed the pattern of T-cell responses induced by these HSP60 peptides in peripheral-blood mononuclear cells (PBMC) of 57 patients with juvenile idiopathic arthritis, 27 healthy controls, and 20 disease controls. We undertook in-vitro MHC binding studies with the identified peptides, and HLA class II typing of a subset of patients with juvenile idiopathic arthritis.

FINDINGS

Five of the eight peptides identified yielded proliferative T-cell responses in 50-70% of PBMC from patients with juvenile idiopathic arthritis irrespective of MHC genotype, but not in PBMC from healthy or disease controls. Although PBMC from both patients with juvenile idiopathic arthritis and healthy controls produced interferon gamma in response to these peptides, only PBMC from patients with the disease produced interleukin 10.

INTERPRETATION

The recorded T-cell-induction in juvenile idiopathic arthritis is tolerogenic. In patients with oligoarticular disease, the immune responses to the HSP60 epitopes identified could contribute to disease remission.

RELEVANCE TO PRACTICE

The broad recognition of these HSP60 epitopes in a population of patients with polymorphic MHC genotypes opens the way for HSP60-peptide immunotherapy, representing a novel treatment option to specifically modulate the immune system in patients with juvenile idiopathic arthritis.

No association between 12 dopaminergic genes and schizophrenia in a large Dutch sample

It has been suggested that genes involved in dopamine neurotransmission contribute to the pathogenesis of schizophrenia. However, reported associations of the disorder with genetic markers in dopaminergic genes have yielded inconsistent results. Possible explanations are differences in phenotyping, genetic heterogeneity, low marker informativity, and the use of small sample sizes. Here, we present a two-stage analysis of 12 dopaminergic genes in a large sample of Dutch schizophrenic patients. To reduce genetic heterogeneity, only patients with at least three Caucasian grandparents of Dutch ancestry were ascertained. An efficient genotyping strategy was used, in which polymorphic microsatellite markers were first screened for association in DNA pools. Promising results were followed up by individual genotyping in an extended sample. The pooled samples consisted of 208 schizophrenic patients and 288 unmatched control individuals. For each of the genes, more than one microsatellite marker was selected where possible, either intragenic or close to the gene. After correcting for multiple testing, significantly different allele frequencies were detected for DRD5 marker D4S615. Subsequently, we individually genotyped this particular marker and another DRD5 marker, as well as a DRD3 marker that could not be analyzed using the pooling strategy. This was done in an extended sample of 282 schizophrenic patients and a control sample of 585 individuals. In this second stage of the study, we found no association between these three markers and schizophrenia. The results of our comprehensive analysis provide no evidence for association between schizophrenia and 12 dopaminergic genes in a large Dutch sample.

Prevalence and clinical significance of resistance to perforin- and FAS-mediated cell death in leukemia

Killer lymphocytes play a central therapeutic role in graft-versus-leukemia following allogeneic hematopoietic stem cell transplantation (HSCT). The Perforin/Granzyme and FAS/CD95 pathways are of crucial importance in tumor cell elimination by killer cells. In this study, we have examined whether hematological malignancies are resistant to perforin and anti-FAS antibodies. Leukemic cells were studied from 29 patients suffering either from acute or chronic myeloid leukemia (AML or CML), acute or chronic lymphoid leukemia, or non-Hodgkin's lymphoma. An average of 49 vs 5% of specific cell killing was found when using perforin vs anti-FAS antibodies, respectively. Interestingly, resistance towards both perforin and anti-FAS antibodies was found exclusively in leukemic cells from patients with myeloid leukemia. Analysis of leukemic cells from patients with CML, suffering from leukemia relapse after HSCT and given donor lymphocyte infusion (DLI) to induce remission, indicated that the effectiveness of treatment with DLI was not associated with sensitivity of leukemic cells to perforin. In conclusion, resistance towards anti-FAS antibodies is a common phenomenon in leukemia/lymphoma, whereas perforin resistance occurs only in myeloid leukemia. However, as a single parameter, perforin resistance does not appear to be suitable to predict the outcome of DLI.

Identification of immunodominant epitopes derived from the respiratory syncytial virus fusion protein that are recognized by human CD4 T cells

Memory CD4 T-cell responses against respiratory syncytial virus (RSV) were evaluated in peripheral blood mononuclear cells of healthy blood donors with gamma interferon enzyme-linked immunospot (Elispot) assays. RSV-specific responses were detected in every donor at levels varying between 0.05 and 0.3% of CD4 T cells. For all donors tested, a considerable component of the CD4 T-cell response was directed against the fusion (F) protein of RSV. We characterized a set of 31 immunodominant antigenic peptides targeted by CD4 T cells in the context of the most prevalent HLA class II molecules within the Caucasian population. Most antigenic peptides were HLA-DR restricted, whereas two dominant DQ peptides were also identified. The antigenic peptides identified were located across the entire sequence of the F protein. Several peptides were presented by more than one major histocompatibility complex class II molecule. Furthermore, most donors recognized several F peptides. Detailed knowledge about immunodominant antigenic peptides will facilitate the ability to monitor CD4 T-cell responses in patients and the measurement of correlates of protection in vaccinated subjects.

Influence of HLA-A, HLA-B, and HLA-DR matching on rejection of random corneal grafts using corneal tissue for retrospective DNA HLA typing

AIM

To establish if coincidental HLA-A, HLA-B, and HLA-DR tissue matching is associated with a reduced likelihood of corneal graft rejection.

METHODS

Organ culture preserved random donor corneas were used for penetrating keratoplasty (PKP). Corneal tissue from all graft recipients and donors or blood samples from recipients after repeated transplantation were obtained in order to perform retrospective molecular HLA typing. A group of 21 recipients with a rejection episode (cases) after corneal transplantation was compared with a control group of non-rejectors (n = 43). 31 graft recipients were considered as high risk patients. The influence of HLA-A, HLA-B, and HLA-DR matching on rejection free graft survival time was analysed with Kaplan-Meyer statistics and Cox regression.

RESULTS

A prolonged rejection free survival time was observed in graft recipients with one or two HLA-A matches (log rank test, p = 0.034). This effect was also observed in high risk graft recipients with one or two HLA-DR matches (log rank test, p = 0.030).

CONCLUSIONS

Coincidental HLA-A and HLA-DR matches were observed and associated with a prolonged rejection free survival time in the total group and in the high risk group, respectively. These results support the beneficial effect of prospective HLA-A and HLA-DR typing upon corneal graft survival.

Prevention of acute graft-versus-host-disease by selective depletion of T cells reactive with minor histocompatibility antigens on epithelial cells

Graft-versus-host disease (GVHD) is a major obstacle in allogeneic hematopoietic stem cell transplantation (HSCT). Mature donor T-cells present in the graft play a pivotal role in the development of acute GVHD. On the other hand, mature donor T-cells in the graft are also crucial for the elimination of residual tumor cells still present in the patient after HSCT. Whether donor T cells act non-specifically against the patient, including an overlapping GVHD/GVL reactivity, or some donor T cells have GVHD reactivity while other donor T cells have GVL reactivity is still unclear. Some in-vitro data are suggestive that selective T cell depletion techniques are possible by which GVHD-reactive T cells can be eliminated while GVL-reactive T cells are preserved. Here we update some approaches of selective T cell depletion that have been developed in our laboratory.

Primary human keratinocytes as targets in predicting acute graft-versus-host disease following HLA-identical bone marrow transplantation

Graft-versus-host-disease (GVHD) remains a major problem following allogeneic bone marrow transplantation (BMT) and manifests itself mainly by damage to epithelial cells of the skin, gut and bile ducts. Reliable tests to predict GVHD are lacking. We developed an assay in which donor T cells are stimulated by patient keratinocytes (KCs), compared that with stimulation by patient peripheral blood mononuclear cells (PBMCs) and studied the relationship to GVHD. In 27 patients undergoing HLA-identical BMT for haematological malignancies, donor T-cell reactivity was determined as the helper T-lymphocyte precursor (HTLp) frequency against host PBMCs (25 patient-donor pairs) and host KCs (20 patient-donor pairs). KCs were obtained by shave biopsies and cultured with interferon (IFN)-gamma to induce HLA class II expression. In assays using patient KCs and donor T cells, anti-CD28 antibody was added to compensate for the lack of co-stimulatory molecules on KCs. Results were related to the occurrence of GVHD. As BMTs were performed with partially T cell-depleted grafts, GVHD was limited to grade 0 (five patients), grade I (seven patients) and grade II (12 patients). No differences were found in donor T-cell reactivity to patient PBMCs, as expressed as HTLp frequency in patients with or without GVHD. However, significant differences (P < 0.01) were found in donor T-cell reactivity to patient KCs when comparing patients with and without GVHD. Donor HTLp frequencies against patient KCs give a better prediction of GVHD than those against patient haemopoietic cells following HLA-identical BMT, which may indicate that at least some minor non-HLA histocompatibility antigens present on KCs are different from those on haemopoietic cells.

Expression of accessory molecules for T-cell activation in peripheral nerve of patients with CIDP and vasculitic neuropathy

Vasculitic neuropathy and chronic inflammatory demyelinating polyneuropathy (CIDP) are neuropathies characterized by a T-lymphocyte infiltrate in the peripheral nerves. The microenvironment in which these T cells become activated, and the molecules and cells that play a role in this process are incompletely understood. Using immunohistochemical analysis, we studied the effect of the presence of adhesion, costimulatory and antigen-presenting molecules on different cell types as a precondition for local T-cell activation in human sural nerve biopsies of seven patients with CIDP, three patients with vasculitic neuropathy and three healthy controls. In biopsies from CIDP and vasculitic neuropathy patients, but not in those from healthy controls, Schwann cells expressed the adhesion/T-cell stimulatory molecule CD58 (LFA-3). The CD58 molecule was also present on endothelial cells of all vasculitic neuropathy patients and one CIDP patient. In biopsies from normal controls and patients, CD54 (ICAM-1) expression was detectable on microvascular endothelial cells. In addition, expression of the costimulatory molecule CD86 was detected on vascular tissue in patients with vasculitic neuropathy. Although macrophages were always present in all subjects, expression of the major histocompatibility complex (MHC)-like molecule CD1a by macrophages was restricted to biopsies from two CIDP patients and one vasculitic neuropathy patient. Unexpectedly, Schwann cells of a single vasculitis patient strongly expressed CD1b, a molecule involved in the presentation of self-glycolipids to T cells. Schwann cells in biopsies from patients and normal controls expressed high levels of the invariant chain, CD74, a molecule involved in the intracellular sorting of MHC class II molecules. There was no evidence for the presence of dendritic cells in sural nerve biopsies. These findings support a model in which T-cell activation can be initiated and/or perpetuated locally in sural nerve biopsies of patients with CIDP and vasculitic neuropathy, and predict an important role for Schwann cells and endothelial cells.

Determination of helper T-cell precursor frequencies against non-haemopoietic cells: comparison of co-stimulation provided by anti-CD28 antibody versus the cellular ligand B7-1

Helper T-cell precursor frequency assays (HTLp-assays) are commonly used in transplantation to examine the frequency of T cells reactive against donor or host alloantigens. In these assays, peripheral blood mononuclear cells (PBMCs) are most often used as stimulator cells. However, cells targeted after transplantation do not always belong to the haematopoietic lineage and may express different alloantigens, especially minor histocompatibility antigens (mHags). Non-haematopoietic cells lack expression of the B7 co-stimulatory molecules needed to activate primary T cells that can be supplied by anti-CD28 (alphaCD28) antibodies or transfection with B7-1 coding sequences. At present, it is not known how these two ways of supplied co-stimulation compare in HTLp assays. B7-1-transfected A431 keratinocytes (A431B7-1) induced higher proliferative responses in allogeneic primary T cells and more interleukin (IL) 2 production than that induced by A431 cells plus alphaCD28, whereas the kinetics of proliferation and IL-2 production were similar. Neither cross-linking of alphaCD28 bound to T cells nor prevention of IL-2 resorption by the anti-IL-2 receptor resulted in improved proliferation or IL-2 production. Results of HTLp assays indicated that A431B7-1 activated on average 7.5 times more alloreactive IL-2-producing T cells than A431 cells plus alphaCD28. We conclude that primary T-cell alloresponses against major histocompatibility complexes (MHCs) and mHags expressed on non-haematopoietic cells can be measured in HTLp assays using supplied co-stimulation, although alphaCD28 yields an intrinsic underestimation of actual frequencies.

Selective depletion of major and minor histocompatibility antigen reactive T cells: towards prevention of acute graft-versus-host disease

Development of acute graft-versus-host disease (aGVHD) following HLA-identical sibling bone marrow transplantation (BMT) remains a serious complication. A selective depletion of T cells has proved to be effective in preventing aGVHD but is associated with relapse and increased incidence of infection. As aGVHD is directed mainly against epithelial tissues we examined whether it would be feasible to selectively deplete T cells reactive with epithelial cells whilst preserving other specificities. Donor T cells which express HLA-DR, CD25, CD69 and CD71 activation markers after cocultivation with patient keratinocytes were depleted using magnetic cell separation techniques. Depletion of major as well as minor histocompatibility antigen activated T cells revealed a significant (P = 0.004 and P = 0.031, respectively) 10-fold decrease in the frequency of donor T lymphocyte precursors reactive with patient keratinocytes. The frequency reactive with third-party and patient peripheral blood mononuclear cells, including leukaemia cells, remained unchanged, supporting the notion that aGVHD and graft-versus-leukaemia (GVL) may be separable. This alloantigen-specific depletion may be used in matched unrelated as well as HLA-identical sibling BMT for reducing aGVHD whilst conserving GVL.

The effect of immunotoxins directed against CD80 and CD86 on primary T-cell alloresponses

Activation of primary resting T cells requires costimulation which can be delivered by the B7 molecules (CD80 and CD86) expressed on activated antigen-presenting cells (APC). In the present study, we examined in vitro effects of immunotoxins (ITs) composed of gelonin conjugated to mAbs against CD80 or CD86 (alphaCD80-IT and alphaCD86-IT). The specificity of both ITs was demonstrated using CD80 and CD86 transfected cell lines. In primary mixed lymphocyte cultures (MLCs), it was found that the average inhibitory capacity of alphaCD86-IT (72%) and alphaCD80-IT (30%) was significantly higher than alphaCD86 (54%) and alphaCD80 (11%). In reculture MLC experiments it was found that peripheral blood mononuclear cells pretreated with alphaCD86/alphaCD80 regained full stimulatory capacity whereas alphaCD86-IT/alphaCD80-IT pretreatment induced >95% loss of stimulatory capacity. Our results therefore demonstrate that these alphaB7-ITs functionally block B7-CD28 costimulatory signaling and eliminate activated APC.

Is there an indication for HLA-DR typing for individual patients with rheumatoid arthritis?

The clinical expression of rheumatoid arthritis (RA) varies considerably among individual patients. Genetic variations in human leucocyte antigen (HLA) may influence susceptibility to RA and the severity of the disease. The literature concerning the association of HLA-DR with the susceptibility to and the clinical expression of RA is reviewed here, taking into account the different populations studied and different typing techniques. An association between the 'shared epitope' and RA susceptibility is present on a group level and may be of some pathophysiological interest. However HLA-DR typing is not useful as a diagnostic test for individuals. The reported associations between HLA-DR and RA severity are various, which might be due to the different typing techniques used. Results from most studies using genomic techniques for HLA-DR typing show an association between HLA-DR4+, DR1+ and a more severe disease course in patient groups. However, this association is too weak to be relevant for individual patients. Therefore, with our current typing techniques, HLA-DR typing is not a useful prognostic test for individual RA patients.

Association of HLA-DR with susceptibility to and clinical expression of rheumatoid arthritis: re-evaluation by means of genomic tissue typing

The clinical expression of rheumatoid arthritis (RA) varies considerably among individual patients. Genetic variations in human leucocyte antigen (HLA) may influence clinical expression. We re-examined the association of HLA-DR with susceptibility to and clinical expression of RA using genomic tissue typing, since most studies were based on (less reliable) serological techniques. Seventy-eight patients with recent-onset RA, all participating in a clinical trial on therapeutic strategies, were HLA-DR typed by means of low-resolution genomic typing. Cumulative disease activity within the first 3 yr of disease was measured. Of the RA patients, 54% expressed DR4 (DR4+) vs 26% of healthy controls. Rheumatoid factor (RF)-positive patients had a higher cumulative disease activity than RF-negative patients. Patients who were either DR1+ or DR4+ had a higher cumulative disease activity than those who expressed neither DR1 nor DR4. This association was less obvious after correction for RF status. The association of DR52+ (DR3, 5, 6) and a lower cumulative disease activity could also not be demonstrated after correction for RF status. Among RF-negative patients, DR51+ (or DR2+) was associated with a higher cumulative disease activity. Other HLA-DR types (including DR1 and DR4 separately) were not associated with the severity of RA. DR4 was associated with susceptibility to RA in our patients; HLA-DR low-resolution genomic tissue typing did not yield additional information to RF status for the clinical identification of individual patients with a poor prognosis.

B7-1 (CD80) as target for immunotoxin therapy for Hodgkin's disease

In this preclinical study, the potential applicability of an anti-B7-1 immunotoxin (IT) for the treatment of Hodgkin's disease (HD) was investigated. Immunohistochemical analysis demonstrated strong expression of B7-1 on Hodgkin and Reed-Sternberg (R-S) cells and clear expression on dendritic cells, macrophages and some B-cells in tissues, but not on other tissue cells. Flow cytometric analysis demonstrated that B7-1 was expressed on a few monocytes, but not on CD34+ cells from bone marrow, resting T- or B-cells from peripheral blood or epithelial and endothelial cell lines. An anti-B7-1 immunotoxin containing the anti-B7-1 monoclonal antibody (MAb) B7-24 and saporin as toxin moiety was constructed and showed an affinity similar to that shown by the native MAb. It exhibited strong cytotoxicity against the B7-1+ B-cell line Raji (IC50 10(-11) M), R-S cell lines HDLM2, KM/H2 and L428 and also against a B7-1-transfected epithelial cell line, A431, whose parental line lacks expression of B7-1. In clonogenic assays with Raji cells or KM/H2 cells, a 3- or 4-log kill, respectively, was observed. No cytotoxicity was found against the B7-1- epithelial and endothelial cell lines or against haematopoietic progenitor cells. In conclusion, an anti-B7-1 immunotoxin was developed that had good cytotoxicity against R-S cell lines and that may be used in the elimination of R-S cells in vivo. A concomitant elimination of activated antigen-presenting cells may avoid development of antitoxin and anti-mouse Ig responses and allow repeated administration.

Human B7-1 is more efficient than B7-2 in providing co-stimulation for alloantigen-specific T cells

Besides a signal via the T cell receptor/CD3 complex, an additional costimulatory signal is required for optimal T cell activation. This signal can be delivered by interaction of either B7-1 or B7-2 expressed by antigen-presenting cells with CD28 on the T cells. Comparison of the function of B7-1 and B7-2 in different experimental animal systems generated conflicting data on the roles for the co-stimulatory molecules. We therefore investigated whether there are differences between B7-1 and B7-2-mediated co-stimulation in an alloantigen-specific primary T cell response induced by B7-transfected human cell lines of epithelial origin. Both transfected keratinocyte cell lines efficiently induce T cell proliferation and the ratios of stimulator versus responder cells are similar. The kinetics of proliferation and interleukin (IL)-2, IL-4 and interferon-gamma production are also comparable between both transfectant lines. However, despite equal B7 expression levels, it is consistently found that the magnitude of the B7-1-induced T cell proliferation was higher than that of B7-2. Comparison of precursor frequencies of helper T lymphocytes responsive with either B7-1 or B7-2 revealed that the frequency of B7-1-responsive T cells was higher than that of B7-2, and that the frequency of cells activated by a combination of B7-1 and B7-2 did not differ significantly from that of B7-1 alone. We therefore conclude that the B7-2-responsive T cells are part of the B7-1-responsive population, and that B7-1 on keratinocytes is more efficient in providing co-stimulation for alloantigen-specific T cells.

Alloantigen-specific T-cell anergy induced by human keratinocytes is abrogated upon loss of cell-cell contact

The activation of primary human T cells largely depends on the expression of both major histocompatibility complex (MHC) class II and B7 molecules on antigen-presenting cells (APC), whereas APC expressing HLA class II but not B7 antigens are expected to induce anergy. According to this concept, interferon-gamma (IFN-gamma)-activated keratinocytes (KC) expressing HLA class II but not B7 costimulatory antigens should be able to induce anergy. However, in terms of anergy versus activation contradicting data have been published on the outcome of interaction between T cells and human KC. In addition, it has been shown that human KC can express a B7-like molecule with unknown function, whereas MHC expression may be functionally impaired. To evaluate this item we transfected the human A431 KC cell line with B7-1 coding sequences and up-regulated HLA-DR by treatment with IFN-gamma, yielding A431DR,B7-1 cells. Irradiated A431DR,B7-1 cells were found to be capable of inducing vigorous proliferative primary T-cell responses in resting allogeneic T cells, whereas A431DR cells could induce proliferation only when interleukin-2 (IL-2) was added. These data indicate that KC can present alloantigens, and that lack of costimulatory molecules on KC is the main reason why these cells cannot induce primary T-cell responses. Surprisingly, however, no evidence could be obtained of stable anergy induction by A431DR cells, as T cells contacted with A431DR cells and then transferred to A431DR,B7-1 cells clearly demonstrated alloresponsiveness. T-cell non-responsiveness was maintained only when T cells remained in contact with A431DR cells. These data indicate that, despite expression of HLA class II in the absence of B7 costimulatory molecules, human KC cannot induce stable anergy but rather induce short-term anergy in primary resting T cells.