Alterations In T-cell Function Research Articles

Dendritic Cell Dysfunction in Patients with End-stage Renal Disease.

End-stage renal disease (ESRD) with immune disorder involves complex interactions between the innate and adaptive immune responses. ESRD is associated with various alterations in immune function such as a reduction in polymorphonuclear leukocyte bactericidal activity, a suppression of lymphocyte proliferative response to stimuli, and a malfunction of cell-mediated immunity at the molecular level. ESRD also increases patients' propensity for infections and malignancies as well as causing a diminished response to vaccination. Several factors influence the immunodeficiency in patients with ESRD, including uremic toxins, malnutrition, chronic inflammation, and the therapeutic dialysis modality. The alteration of T-cell function in ESRD has been considered to be a major factor underlying the impaired adaptive cellular immunity in these patients. However, cumulative evidence has suggested that the immune defect in ESRD can be caused by an Ag-presenting dendritic cell (DC) dysfunction in addition to a T-cell defect. It has been reported that ESRD has a deleterious effect on DCs both in terms of their number and function, although the precise mechanism by which DC function becomes altered in these patients is unclear. In this review, we discuss the effects of ESRD on the number and function of DCs and propose a possible molecular mechanism for DC dysfunction. We also address therapeutic approaches to improve immune function by optimally activating DCs in patients with ESRD.

Intravenous Immunoglobulin Therapy for Persistent Pemphigoid Gestationis with Steroid Induced Iatrogenic Cushing's Syndrome

Dear Editor: A 30-year-old woman developed pemphigoid gestationis (PG) after 20 weeks of gestation during her first pregnancy. Initially, she was treated with prednisone (10~30 mg/d), but she had a miscarriage in the 26th week of pregnancy. After the miscarriage, she was treated with prednisone (30~40 mg/d) and azathioprine (100 mg/d). However, her PG did not show clinical remission and new blisters continued to develop until the 12th post-partum week. Therefore, she was referred to our clinic for further treatment. She had erythematous patches, plaques and tense bullae on both the upper extremities and trunk (Fig. 1A). Histopathological examination of the skin samples showed the presence of subepidermal vesicles with perivascular lymphocytes and eosinophils (Fig. 2A, B). Direct immunofluorescence examination revealed positive, linear deposition of IgG and C3 in the basement membrane zone (Fig. 2C, D). Therefore, we confirmed the diagnosis of PG and started her on high-dose systemic corticosteroids; however, after receiving the treatment, she rapidly gained weight and developed moon face. Therefore, we performed a rapid adrenocorticotropic hormone stimulation test and measured her 24-hour urine cortisol level; on the basis of the test results, she was diagnosed with iatrogenic Cushing's syndrome. Therefore, she was started on prednisone (40~60 mg/d) and azathiprine (100 mg/d), but the symptoms persisted. After considering further treatment options, we decided to administer intravenous immunoglobulin (IVIG) therapy at a dose of 0.5 g kg-1 day-1 for 2 consecutive days. Fig. 1 (A) Large tense bullae and erythematous pruritic plaques on the arm. (B) Improved skin lesions with postinflammatory hyperpigmentation after intravenous immunoglobulin combination treatment. Fig. 2 (A) Subepidermal blister with superficial inflammatory infiltrate. (B) Superficial perivascular lymphohistiocytic infiltration, with moderate infiltration of eosinophils. Linear staining for (C) IgG, (D) C3 at the basement membrane zone. (A) H&E, ... After receiving the IVIG therapy, her skin lesions quickly subsided (Fig. 1B), so prednisone was tapered down to 10 mg/day. She was also administered a steroid at a low dose for 8 weeks for treating her Cushing's syndrome. At the follow-up after 3 months, no lesions were found on the patient. PG is a rare autoimmune-mediated blistering disease, usually occurring in the late pregnancy and immediate postpartum period. Many patients experience spontaneous resolution during the latter part of gestation only to experience a flare at the time of delivery. However, the persistence of disease activity for many years postpartum has been reported. Numerous immunosuppressive treatments have been reported for PG1. If the disease persists, treatment options are limited because they have potential side-effects, e.g. development of Cushing's syndrome, as seen in our patient. IVIG has been used to treat various autoimmune blistering diseases2. Many authors reported the use of IVIG for treating PG. The immunomodulatory actions of IVIG are mediated via several immune-mediated mechanisms, such as complement blockade and degradation, Fc receptor blockade and induction of immunomodulatory Fc receptors, inhibition of B cells, and alteration of T-cell function, cytokine modulation, and cellular migration3. IVIG therapy is relatively safe, and severe adverse events associated with the use of IVIG are rare. Headache and acute cutaneous reactions are the most common adverse effects of the therapy, while renal failure, thromboembolic events, and anaphylaxis have rarely been reported in association with IVIG therapy3. It is difficult to differentiate refractory PG from epidermolysis bullosa acquisita using only clinical, histological and direct immunofluorescence findings. Therefore, the findings of enzyme-linked immunosorbent assay and indirect immunofluorescence performed on sodium chloride-split skin are helpful in the differentiation4. We confirmed the diagnosis of PG in the case of our patient, as PG manifests itself during pregnancy, moreover, the patient achieved remission after one-cycle treatment2,3. PG is a rare disease and only 4 cases of PG treated with IVIG have been reported to date. We presented a case of persistent PG treated with IVIG combination therapy. IVIG should be considered as a therapeutic option in patients that fail to respond to conventional immunosuppressive treatment.

A challenge for the future: aging and HIV infection

Older individuals (≥50 years of age) are increasingly becoming a new at-risk group for HIV-1 infection and, together with those surviving longer due to the introduction of anti-retroviral therapy (ART), it is predicted that more than half of all HIV-1-infected individuals in the United States will be greater than 50 years of age in the year 2015. Older individuals diagnosed with HIV-1 are prone to faster disease progression and reduced T-cell reconstitution despite successful virologic control with anti-retroviral therapy (ART). There is also growing evidence that the T-cell compartment in HIV-1(+) adults displays an aged phenotype, and HIV-1-infected individuals are increasingly diagnosed with clinical conditions more commonly seen in older uninfected persons. As aging in the absence of HIV infection is associated with alterations in T-cell function and immunosenescence, the combined impact of both HIV-1 infection and aging may provide an explanation for poorer clinical outcomes observed in older HIV-1-infected individuals. Thus, the development of novel therapeutics to stimulate immune function and delay immunosenescence is critical and would be beneficial to both the elderly and HIV-1-infected individuals.

CD28 signaling in neutrophil induces T-cell chemotactic factor(s) modulating T-cell response

We previously reported that human peripheral blood neutrophils express CD28 and interact with macrophage B7 to generate CD28 signaling through PI-3 kinase. Here, we demonstrate that crosslinking of CD28 on neutrophils results in the release of IFN-γ, which restricts amastigote growth and modulates CD4 + T cells cytokine secretion. CD28 crosslinking also induces a T-cell chemotactic factor (TCF) that induces chemotactic migration of CD4 + T cells. Based on our previous and the current set of data, we propose an operational model explaining how neutrophils are involved in Leishmania infection and how the reported effect of neutrophils on the control of infection is mediated by alteration of T-cell function.

Severe injury triggers antigen-specific T-helper cell dysfunction.

Although it is established that post-injury immune dysfunction involves alterations in T-cell function, the effects of injury on T-cell function in vivo are poorly understood. This study uses a mouse injury model and an antigen immunization approach to investigate the influence of injury on antigen-specific T-helper cell function. We report here that injury triggered a significant reduction in antigen-specific T-helper-1 (Th1)-dependent IgG2a antibody formation, while IgM, IgG1, and IgE production was unchanged. In addition, injury caused a reduction in cytokine production (IL-2, IFNgamma and IL-10) by antigen-stimulated T-cells. We also demonstrate that interleukin 12 (IL-12), a cytokine that promotes Th1 cell differentiation, restored IgG2a antibody formation and corrected the injury-induced reduction in antigen-stimulated cytokine production. Taken together, these findings indicate that severe injury induces a dramatic reduction in Th1 cell function in vivo and suggest that therapies designed to restore Th1 cell function may be beneficial to the injured host.

Application of tumor, bacterial and parasite susceptibility assays to study immune alterations induced by environmental chemicals.

Model systems to study the effects of chemicals of environmental concern on bacterial and parasitic diseases as well as the immunosurveillance and destruction of transplantable tumor cells were described and evaluated. Studies were conducted in female B6C3F1 mice following adult or pre/postnatal exposure to several prototype chemicals. The prototype chemicals employed included the synthetic estrogen diethylstilbestrol (DES), the polycyclic aromatic hydrocarbon benzo(a)pyrene (B[a]P), and the carcinogenesis promoting agent 12-0-tetradecanoyl-phorbol-13-0-acetate (TPA). The host resistance models employed depend primarily on functional thymus-dependent immunity, although humoral immunity is suggested to have a role in the parasite model as well. These models include: subcutaneous challenge with a dose of PYB6 tumor cell causing a 10-20% incidence (TD(10-20)) of tumor; intravenous challenge with B16 melanoma cells; challenge with a dose of Listeria monocytogenes causing a 10-20% incidence of mortality (LD(10-20)); challenge with a dose of E. coli lipopolysaccharide endotoxin causing a 10-20% incidence of lethality (LD(10-20)); and challenge with larvae of Trichinella spiralis for parasite expulsion kinetic studies. Increased mortality was observed following Listeria monocytogenes challenge in DES-exposed mice. B(a)P and TPA exposure did not alter host resistance to this organism. The increased mortality observed following DES was associated with a significant increase in the number of viable Listeria in the spleens and livers at 4 days, a time when T-cell immunity is thought to be expressed, but bacterial counts were similar to control mice at day 1, a time when MPhi are thought to exert their greatest effect. These data suggest that the increased Listeria susceptibility found following DES exposure may result from a T-cell defect, although the intracellular killing capacity of DES-treated Mvarphi's has not been well examined. Tumor susceptibility studies following challenge with 5 x 10(3) viable syngeneic PYB6 tumor cells revealed that nontreated adult B6C3F1 mice resisted tumor formation, with only a 10-20% incidence of tumor formation. In contrast, mice exposed to DES or TPA as adults had a tumor frequency of from 70-100% following TPA and up to 90% following DES exposure. In all cases the tumors were progressive and resulted in death. B(a)P did not alter the frequency of tumor incidence from controls in this model. Preliminary data, using the B16 melanoma intravenous challenge model and (125)IUdR to quantitate tumor mass revealed this model was sensitive to non-specifically activated macrophage kill. DES treated mice with activated macrophages did not demonstrate increased tumor mass, while mice exposed to TPA or the potent immunosuppressive agent cyclophosphamide had a significantly increased tumor mass in their lungs. Expulsion of Trichinella spiralis adults from the gut also apparently required functional T-cells and possibly some element of humoral immunity. Mice exposed to DES and B(a)P exhibited increased numbers of adult worms in the gut at day 14. Sensitivity to gram-negative endotoxin (LPS) was apparently increased following exposure to DES or B(a)P. These data suggest that the detoxification of LPS is related to an intact Mvarphi population. The data presented here demonstrate the sensitivity of the host resistance assay panel proposed for detecting immune alteration. Alteration of T-cell function appeared to correlate with increased susceptibility to bacterial and tumor cell challenge.

Application of Tumor, Bacterial and Parasite Susceptibility Assays to Study Immune Alterations Induced by Environmental Chemicals

Model systems to study the effects of chemicals of environmental concern on bacterial and parasitic diseases as well as the immunosurveillance and destruction of transplantable tumor cells were described and evaluated. Studies were conducted in female B6C3F1 mice following adult or pre/postnatal exposure to several prototype chemicals. The prototype chemicals employed included the synthetic estrogen diethylstilbestrol (DES), the polycyclic aromatic hydrocarbon benzo(a)pyrene (B[a]P), and the carcinogenesis promoting agent 12-0-tetradecanoyl-phorbol-13-0-acetate (TPA). The host resistance models employed depend primarily on functional thymus-dependent immunity, although humoral immunity is suggested to have a role in the parasite model as well. These models include: subcutaneous challenge with a dose of PYB6 tumor cell causing a 10-20% incidence (TD10–20) of tumor; intravenous challenge with B16 melanoma cells; challenge with a dose of Listeria monocytogenes causing a 10-20% incidence of mortality (LD10–20); challenge with a dose of E. coli lipopolysaccharide endotoxin causing a 10-20% incidence of lethality (LD10–20); and challenge with larvae of Trichinella spiralis for parasite expulsion kinetic studies. Increased mortality was observed following Listeria monocytogenes challenge in DES-exposed mice. B(a)P and TPA exposure did not alter host resistance to this organism. The increased mortality observed following DES was associated with a significant increase in the number of viable Listeria in the spleens and livers at 4 days, a time when T-cell immunity is thought to be expressed, but bacterial counts were similar to control mice at day 1, a time when MΦ are thought to exert their greatest effect. These data suggest that the increased Listeria susceptibility found following DES exposure may result from a T-cell defect, although the intracellular killing capacity of DES-treated Mϕ's has not been well examined. Tumor susceptibility studies following challenge with 5 × 103 viable syngeneic PYB6 tumor cells revealed that nontreated adult B6C3F1 mice resisted tumor formation, with only a 10-20% incidence of tumor formation. In contrast, mice exposed to DES or TPA as adults had a tumor frequency of from 70-100% following TPA and up to 90% following DES exposure. In all cases the tumors were progressive and resulted in death. B(a)P did not alter the frequency of tumor incidence from controls in this model. Preliminary data, using the B16 melanoma intravenous challenge model and 125IUdR to quantitate tumor mass revealed this model was sensitive to non-specifically activated macrophage kill. DES treated mice with activated macrophages did not demonstrate increased tumor mass, while mice exposed to TPA or the potent immunosuppressive agent cyclophosphamide had a significantly increased tumor mass in their lungs. Expulsion of Trichinella spiralis adults from the gut also apparently required functional T-cells and possibly some element of humoral immunity. Mice exposed to DES and B(a)P exhibited increased numbers of adult worms in the gut at day 14. Sensitivity to gram-negative endotoxin (LPS) was apparently increased following exposure to DES or B(a)P. These data suggest that the detoxification of LPS is related to an intact Mϕ population. The data presented here demonstrate the sensitivity of the host resistance assay panel proposed for detecting immune alteration. Alteration of T-cell function appeared to correlate with increased susceptibility to bacterial and tumor cell challenge.