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D A Hafler

Publications and source records attributed to D A Hafler.

At least 19 recordsLinked to original sources
PubMed1992

CTLA-4 and CD28 mRNA are coexpressed in most T cells after activation. Expression of CTLA-4 and CD28 mRNA does not correlate with the pattern of lymphokine production.

Ag-presenting cells provide at least two distinct signals for T cell activation. T cell receptor-dependent stimulation is provided by presentation of a specific peptide Ag in association with MHC molecules. In addition, APC also supply costimulatory signals required for T cell activation that are neither Ag- nor MHC restricted. One such costimulatory signal is mediated via the interaction of B7 on APC with the CD28 receptor on T cells. Recently, CTLA-4 has been shown to be a second B7 receptor on T cells. In the present report, we have examined the expression of CD28 and CTLA-4 on a panel of resting and activated normal T cell subsets and T cell clones by RNA blot analysis in an attempt to determine whether their expression defines reciprocal or overlapping subsets. CD28 was detected in resting T cells, whereas CTLA-4 was not. After stimulation with PHA and PMA for 24 h, CTLA-4 mRNA was expressed in both the CD4+ and CD8+ subsets as well as in CD28+ T cells. We examined 37 human and six murine T cell clones that had been previously characterized for their cytokine production. After activation, CTLA-4 and CD28 mRNA were coexpressed in 36 of 37 human T cell clones and all six murine T cell clones. These included T cells of CD4+8-, CD4-8+, and CD4-8- phenotypes as well as clones with Th1 and Th2 cytokine profiles. In contrast, CD28 but not CTLA-4 mRNA was detected in leukemic T cell lines and myelomas. CTLA-4 and B7 mRNA but not CD28 mRNA was detected in two long term HTLV-I-transformed T cell lines. These data demonstrate that CD28 and CTLA-4 mRNA are coexpressed in most activated T cells and T cell clones, providing evidence that they do not define reciprocal subsets. Moreover, they are consistent with the hypothesis that B7 transmits its signal through a single receptor, CD28, on resting T cells, and multiple receptors, CD28 and CTLA-4, on activated T cells.

Abatacept↗
PubMed1992

Early signaling defects in human T cells anergized by T cell presentation of autoantigen.

Major histocompatibility complex class II-positive human T cell clones are nontraditional antigen-presenting cells (APCs) that are able to simultaneously present and respond to peptide or degraded antigen, but are unable to process intact protein. Although T cell presentation of peptide antigen resulted in a primary proliferative response, T cells that had been previously stimulated by T cells presenting antigen were completely unresponsive to antigen but not to interleukin 2 (IL-2). In contrast, peptide antigen presented by B cells or DR2+ L cell transfectants resulted in T cell activation and responsiveness to restimulation. The anergy induced by T cell presentation of peptide could not be prevented by the addition of either autologous or allogeneic B cells or B7+ DR2+ L cell transfectants, suggesting that the induction of anergy could occur in the presence of costimulation. T cell anergy was induced within 24 h of T cell presentation of antigen and was long lasting. Anergized T cells expressed normal levels of T cell receptor/CD3 but were defective in their ability to release [Ca2+]i to both alpha CD3 and APCs. Moreover, anergized T cells did not proliferate to alpha CD2 monoclonal antibodies or alpha CD3 plus phorbol myristate acetate (PMA), nor did they synthesize IL-2, IL-4, or interferon gamma mRNA in response to either peptide or peptide plus PMA. In contrast, ionomycin plus PMA induced both normal proliferative responses and synthesis of cytokine mRNA, suggesting that the signaling defect in anergized cells occurs before protein kinase C activation and [Ca2+]i release.

Antigen-Presenting Cells↗
PubMed1992

Gamma delta T-cell receptor repertoire in acute multiple sclerosis lesions.

Gamma delta T cells are a distinct lymphocyte population that can exhibit reactivity with heat shock proteins over-expressed at inflammatory sites. As gamma delta T cells may be involved in the central nervous system (CNS) inflammatory process in multiple sclerosis (MS), we examined T-cell populations in MS plaque tissue by quantitative immunohistochemistry and sequence analysis of T-cell antigen receptor (TCR) delta chains. Gamma delta T cells that express the variable (V) gene segments V delta 1, V delta 2, and V gamma 2 (V gamma 9) were found to accumulate in acute, demyelinating MS plaques and appeared to have undergone clonal expansion, most likely because of recognition of a specific CNS ligand. Further, 60-kDa and 90-kDa heat shock proteins (hsp60 and hsp90), which may be target antigens for autoreactive gamma delta T cells, were found to be expressed in normal CNS tissue and overexpressed in acute MS plaques. In acute plaques, hsp60 was found in foamy macrophages, while hsp90 was detected in reactive astrocytes. These results provide evidence for a role of gamma delta T cells in active stages of MS.

Base Sequence↗
PubMed1992

Characterization of HTLV-I in vivo infected T cell clones. IL-2-independent growth of nontransformed T cells.

Mononuclear cells from subjects infected with human T lymphotrophic virus type I (HTLV-I) display a unique ability to proliferate in vitro in the absence of mitogens or exogenous growth factors. Subjects who have developed an HTLV-I-associated myelopathy (HAM) show an even higher degree of spontaneous proliferation concomitant with transcription of the HTLV-I provirus. The mechanism underlying HTLV-I-induced T cell activation was investigated by characterizing a series of HTLV-I-infected T cell clones generated from the blood of subjects with HAM. Approximately 15% of the T cell clones generated were HTLV-I infected as determined by polymerase chain reaction and Southern blotting. Infected T cell clones displayed altered growth kinetics as they continued to incorporate tritiated thymidine 7 to 14 days after stimulation, a time when noninfected T cell clones had returned to a resting state. This was not due to transformation as all the T cell clones required periodic restimulation with mitogens and feeder cells for continued growth. Although HTLV-I-infected T cell clones showed increased expression of the IL-2 receptor p55 chain, the spontaneous clonal proliferation was not inhibited by anti-IL-2 receptor mAb. Moreover, the spontaneous clonal proliferation was insensitive to cyclosporin A and FK 506 while being highly sensitive to rapamycin, which is known to inhibit IL-2-mediated signaling. Together these results demonstrate that IL-2 is not required for the HTLV-I-induced spontaneous clonal proliferation and further suggest that HTLV-I may induce signaling pathways replacing an IL-2 receptor signal proximal to the site of action of rapamycin.

Antibodies, Monoclonal↗
PubMed1992

T cell receptor V alpha-V beta repertoire and cytokine gene expression in active multiple sclerosis lesions.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with presumed autoimmune etiology. A recent study has suggested the presence of a restricted T cell receptor (TCR) V alpha repertoire in MS lesions. The presence of such a restricted TCR repertoire at the site of inflammation would have important consequences for the pathogenesis and the ultimate treatment of MS. To further characterize the TCR V alpha and V beta repertoire in MS plaque tissue, we examined a series of 26 histologically well-characterized central nervous system (CNS) tissue specimens from six MS patients as well as samples from five normal postmortem cases and a case of subacute sclerosing panencephalitis. RNA was extracted from frozen sections and cDNAs were amplified by polymerase chain reaction using primers for TCR V alpha (V alpha 1-18) and V beta (V beta 1-19) gene families. This analysis demonstrated a broad TCR V alpha-V beta repertoire in active lesions, while fewer TCR V genes were detected in chronic plaques and control samples. Even though a large number of TCR V alpha and V beta gene segments were present in the majority of active lesions, there were clear differences in the TCR repertoire between plaques from the same case, suggesting that local events influence the TCR repertoire at the level of T cell recruitment or T cell expansion. Examination of cytokine mRNAs demonstrated that IL-1 mRNA was present in the majority of acute and subacute plaques, while IL-2 and IL-4 mRNA were detected in only a few acute lesions. These data demonstrate that the TCR repertoire in MS plaques is polyclonal. However, autoreactive alpha/beta T cells thought to be critical in the initiation of the inflammatory process probably represent a minor fraction of T cells in active MS plaques and may use a limited number of TCR V gene segments for recognition of the autoantigen.

Acute Disease↗
PubMed1992

T-cell activation by autologous human T-cell leukemia virus type I-infected T-cell clones.

A unique feature of both human T-cell leukemia virus type I (HTLV-I) carriers and subjects with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic inflammatory disease of the nervous system, is the presence of large numbers of activated T cells that spontaneously proliferate in vitro. We have investigated the mechanisms of T-cell activation by HTLV-I in freshly isolated blood T cells and in naturally infected T-cell clones obtained by direct single-cell cloning from patients with HAM/TSP. Both CD4+ and CD8+ HTLV-I-infected T-cell clones showed the unusual ability to proliferate in the absence of exogenous interleukin 2 (IL-2). Nevertheless, HTLV-I-infected clones were not transformed, as they required periodic restimulation with phytohemagglutinin and feeder cells for long-term growth. Irradiated or fixed HTLV-I-infected clones were found to induce the proliferation of blood T cells when cocultured, which we refer to as THTLV-1-T cell activation. This THTLV-1-T cell-mediated activation was blocked by monoclonal antibodies (mAbs) against CD2/lymphocyte function-associated molecule 3 (LFA-3), LFA-1/intercellular cell-adhesion molecule (ICAM), and the IL-2 receptor but not by mAbs against class I or class II major histocompatibility complex molecules, HTLV-I gp46, or a high-titer HAM/TSP serum. Spontaneous proliferation of blood T cells from HAM/TSP patients could also be inhibited by mAbs to CD2/LFA-3, LFA-1/ICAM and to the IL-2 receptor (CD25). These results show at the clonal level that HTLV-I infection induces T-cell activation and that such activated T cells can in turn stimulate noninfected T cells by cognate THTLV-1-T cell interactions involving the CD2 pathway.

Antibodies, Monoclonal↗
PubMed1992

T cell vaccination in multiple sclerosis: a preliminary report.

Multiple sclerosis (MS) is a presumed autoimmune disease of the central nervous system. Inoculation of attenuated T cell clones recognizing immunodominant regions of myelin autoantigens can protect animals from the induction of experimental autoimmune diseases. In this phase one trial, we investigated whether inoculations with attenuated T cell clones are feasible in humans for eventual trials with autoreactive clones and whether there are any associated immunologic effects. A total of seven inoculations with attenuated, autologous T cell clones isolated from the cerebrospinal fluid in four subjects with progressive MS was performed. No untoward side effects were observed. Immunologic studies suggested that the inoculation of autologous activated T cell clones followed by partial, short-term, immunosuppression as evidenced by a decrease of subsequent responses to stimulation via the CD2 pathway and increases in the autologous mixed lymphocyte response. We conclude that the use of attenuated autoreactive T cell clones appears feasible for further clinical trials in humans with autoimmune diseases.

Clone Cells↗
PubMed1991

Presentation of autoantigen by human T cells.

Activated human T cells express MHC class II and have been shown to present foreign Ag to autologous T cells. We now demonstrate that MHC class II+ T cell clones can present myelin basic protein (MBP) peptide autoantigen in the absence of traditional APC to autologous MBP reactive T cell clones. MBP peptide-pulsed T cell clones specifically stimulated autologous MBP-reactive T cell clones to flux calcium and proliferate. Activation responses were peptide epitope specific and blocked by mAb to MHC class II, indicating a TCR-mediated response. In addition, mAb to the adhesion molecules LFA-3, CD2, LFA-1, CD29, and to the tyrosine phosphatase CD45 also inhibited proliferation, indicating the involvement of T to T cell interactions. In contrast to peptide Ag, T cell clones did not respond to autologous T cells pulsed with HPLC-purified MBP, suggesting that T cells are unable to process whole MBP. However, batch-purified MBP Ag preparations containing lower m.w. breakdown products were presented by T cells, indicating that naturally occurring breakdown products of autoantigens could be presented by activated T cells in vivo. These results raise the possibility that T cell presentation of autoantigen at inflammatory sites may be important in regulation of immune responses to self Ag.

Amino Acid Sequence↗
PubMed1991

Restricted T cell expression of IL-2/IFN-gamma mRNA in human inflammatory disease.

It has been difficult to demonstrate functionally distinct T cell populations in humans on the basis of cytokine secretion. As previous investigators have examined the T cell cytokine profile from immunized animals, we examined whether Th1 or Th2 type T cells could be identified in the peripheral blood or cerebrospinal fluid (CSF) immune compartments from subjects with or without inflammatory diseases. Using limiting dilution analysis and growth with PHA and IL-2/IL-4, we directly cloned a total of 177 T cells from the peripheral blood and CSF of seven subjects, four with inflammatory disease and three control subjects, and examined the cytokine message profile after stimulation with ionomycin and PMA. We found that most clones from both the peripheral blood and CSF express IL-1, IL-2, IL-4, IFN-gamma, or TNF-alpha cytokine mRNA after activation with ionomycin and PMA. All T cell clones tested produced TNF-alpha mRNA, and all but 14 produced IFN-gamma mRNA. As reported previously, Th0 cells, which produced IFN-gamma, IL-2, IL-4, and IL-5 mRNA, were found in most subjects. In striking contrast, Th1 cells, which expressed IL-2 and IFN-gamma but not IL-4 or IL-5 mRNA, were present in both peripheral blood and CSF of subjects with inflammatory disease but not found in peripheral blood or CSF of subjects without systemic inflammation. Th2 cells, expressing IL-4 and IL-5 but not IFN-gamma or IL-2 mRNA, were not found in any subject. These data present the first evidence for Th1 T cell clones in humans that may be associated with systemic inflammation.

Antigens, CD↗
PubMed1991

Common T-cell receptor V beta usage in oligoclonal T lymphocytes derived from cerebrospinal fluid and blood of patients with multiple sclerosis.

T-cell populations were investigated in the blood and cerebrospinal fluid of patients with multiple sclerosis and other neurological diseases. Individual T cells were directly cloned from the cerebrospinal fluid and blood before in vitro expansion, and their clonotypes were compared by Southern blot analysis of the rearrangement patterns of their T-cell receptor beta chain and gamma chain genes. This allowed the determination of whether two T cell clones shared the same T-cell receptor and thus arose from identical, clonally expanded (oligoclonal) progenitor T cells. As an extension of previous studies, oligoclonal T-cell clones were identified in both cerebrospinal fluid and blood populations in 5 of 9 patients with inflammatory demyelinating disease among a total of 486 blood and cerebrospinal fluid T-cell clones. In contrast, no clonally expanded T-cell populations were found among a total of 424 clones derived from either blood of 4 normal control subjects or blood and cerebrospinal fluid of 8 patients with other neurological diseases. Analysis of T-cell receptor V beta genes among 4 oligoclonal T-cell populations derived from 3 patients with multiple sclerosis demonstrated common usage of the V beta 12 gene segment. These data suggest that oligoclonal T cells share similar specificities and that clonal expansion may have resulted from specific stimulation by an antigen. Moreover, identical clones between blood and cerebrospinal fluid were observed in 3 of 9 patients with demyelinating disease, thus providing further evidence of an equilibrium between peripheral and central nervous system immune compartments.

Adolescent↗
PubMed1991

Suppression of experimental autoimmune encephalomyelitis by oral administration of myelin antigens: IV. Suppression of chronic relapsing disease in the Lewis rat and strain 13 guinea pig.

Oral administration of proteins is a long-recognized method of inducing antigen-specific peripheral immune tolerance. We previously showed that oral administration of myelin basic protein suppresses monophasic experimental autoimmune encephalomyelitis in the Lewis rat when it is given in association with immunization and prior to disease onset. As a potential therapy for human autoimmune disease, it is crucial to determine whether oral tolerance can ameliorate an ongoing immune response. We therefore asked whether oral administration of myelin antigens, after sensitization and disease expression has occurred, could affect immunological, clinical, or pathological features of experimental autoimmune encephalomyelitis. Chronic relapsing experimental autoimmune encephalomyelitis was induced in the Lewis rat and strain 13 guinea pig by immunization with whole guinea pig cord homogenate, complete Freund's adjuvant, and Mycobacterium tuberculosis. Following recovery from the first attack, animals were orally given bovine myelin, guinea pig myelin, or guinea pig myelin basic protein three times per week for up to 3 months. Animals receiving myelin products orally had decreased severity and frequency of clinical relapses, decreased delayed-type hypersensitivity responses to myelin antigens, diminished inflammation in the central nervous system (CNS), and decreased areas of CNS demyelination. In the rat, guinea pig myelin basic protein was as effective as guinea pig myelin in ameliorating the disease and also resulted in decreased serum anti-myelin basic protein antibody levels. No exacerbation of disease or worsening of pathological findings occurred in the animals given myelin products. These results demonstrate that oral administration of myelin antigens can suppress chronic relapsing experimental autoimmune encephalomyelitis and have direct relevance to therapy of human demyelinating disorders such as multiple sclerosis.

Administration, Oral↗
PubMed1991

The coexpression of CD45RA and CD45RO isoforms on T cells during the S/G2/M stages of cell cycle.

The tyrosine phosphatase CD45 is alternatively spliced to generate isoforms of different molecular weights (180-220 kDa) which are differentially expressed on hematopoietic cells. Monoclonal antibodies reacting with either the 180-kDa (UCHL-1, CD45RO) or the 200- to 220-kDa (2H4, CD45RA) isoform have been used to subdivide T cell populations based on their expression of one or the other of these two epitopes. CD45RA T cells have "naive" characteristics of unresponsiveness to recall antigens and prominence in cord blood, while CD45RO T cells are considered "memory" T cells because they proliferate to recall antigens and increase following PHA activation of cord blood. However, we have recently demonstrated the expression of the CD45RA isoform on a subpopulation of CD45RO+ T cell clones, suggesting that CD45RA is not a universal marker for naive T cells. Using propidium iodide staining of the DNA to determine cell cycle stage, we now show that CD45RA expression is significantly higher on T cell clones during the S, G2, and M stages of cell cycle when compared to CD45RA expression on cells in Go and G1. Furthermore, CD45RA expression on cells undergoing mitosis is not limited to long-term activated T cell clones, as uncultured peripheral blood T cells in the S/G2/M phase express significantly more CD45RA. The percentage of T cells coexpressing CD45RA and CD45RO also increases following PHA activation, indicating that T cells in the process of division express both isoforms. These results suggest a potential role of the CD45RA isoform during the stages of cell cycle leading to mitosis.

Antigens, CD↗
PubMed1991

Interleukin-1 corrects the defective autologous mixed lymphocyte response in multiple sclerosis.

Patients with chronic progressive multiple sclerosis (MS) have alterations of T cell regulation that can be measured by in vitro assays and include decreases of the autologous mixed lymphocyte reaction (AMLR). Whether a defect in cytokine secretion was involved in the altered AMLR was investigated in 29 MS patients and 13 age- and sex-matched controls. The response of CD4+ T cell populations to irradiated non-T cells was decreased in MS as compared to control subjects. As previously reported, decreases in the AMLR were similarly observed with whole T cells of MS subjects as compared to controls. The addition of recombinant interleukin (IL)-1 to cultures of either whole T cells or CD4+ T cells with irradiated non-T cells in the AMLR corrected the immune defect in subjects with MS but had no effect on the AMLR in control subjects. In contrast, addition of rIL-2 or rIL-4 to the AMLR did not correct the decreased AMLR in MS patients as compared to controls. The lymphokines IFN-gamma and TGF-beta 2 both decreased the AMLR in MS patients and controls while TNF had no effect. Further, the magnitude of the AMLR response corresponded to IL-1 secretion induced by LPS in the non-T cell population. These studies indicate that defects in IL-1 may be related to immune defects of suppression in MS patients. Selective correction of immunoregulatory defects using lymphokines or their inducers in subjects with autoimmune diseases such as MS may be possible.

CD4-Positive T-Lymphocytes↗
PubMed1991

Immunologic effects of cyclophosphamide/ACTH in patients with chronic progressive multiple sclerosis.

We examined immune function and changes in T cell populations over a 1-year period in a series of progressive multiple sclerosis (MS) patients treated with different regimens of cyclophosphamide/ACTH as part of the Northeast Multiple Sclerosis Treatment Group. Our studies were designed to determine the effect of different cyclophosphamide/ACTH regimens on T cell populations and functional immune assays and to determine whether immune measures could be identified to predict which patients responded favorably to treatment. Cyclophosphamide/ACTH infusions significantly decreased the proportion of peripheral blood CD4+ T cells at 2, 6 and 12 months following treatment while there was a tendency for increased CD8 expression. This was associated with significant decreases of CD4/CD8 ratios at 2, 6 and 12 months following treatment compared to pretreatment. No changes in CD3+ T cells were observed while there were increased percentages of CDw26 (Ta1) positive and IL-2 positive T cells following treatment. The only T cell populations predictive of improvement were percentages of either CD3+ or CD4+ cells where increased percentages of either these populations at 2 months following cyclophosphamide/ACTH infusions were associated with improvement at both 6 and 12 months. In terms of functional immune measures, we found that cyclophosphamide/ACTH treatment decreased the level of proliferation in the allogeneic mixed lymphocyte reaction (MLR) at 2 months and of spontaneous proliferation of mononuclear cells at 12 months following therapy. Changes in spontaneous proliferation were predictive of clinical improvement at 12 months in that subjects with improved scores on the disability status scale (DSS) had decreases in spontaneous proliferation at 12 months as compared to pretreatment, whereas those stable or worse did not change significantly. Thus, our studies have demonstrated specific alterations in immune function following immunosuppression with cyclophosphamide/ACTH and suggest that certain immune measures may be linked to a positive clinical response and thus associated with disease progression in MS.

Adrenocorticotropic Hormone↗
PubMed1991

T-cell recognition of myelin basic protein.

Multiple sclerosis is a chronic inflammatory disease of the central nervous system which has been hypothesized to be autoimmune in nature. To test whether this is the case, Kai Wucherpfennig and colleagues have developed a set of criteria that must be met to satisfy the hypothesis. Here, they present these criteria and assess the extent to which studies to date satisfy them.

Autoantigens↗
PubMed1991

Immunotherapy in autoimmune diseases.

Over the past decade, much progress has been made in our understanding of immunological tolerance of self-antigens and the genetic and molecular basis of T-cell recognition and activation that involves a ternary interaction of foreign or self-antigens with major histocompatibility complex molecules and T-cell antigen receptor gene products. Using this trimolecular complex as a target for immune intervention, animal models of spontaneously occurring and experimentally induced autoimmune diseases have provided opportunities for new immunomodulatory therapeutic approaches. Some of these have encouraging potential and are currently being applied in the immunotherapy of human autoimmune diseases.

Animals↗