Involvement of CD4(+) Th1 cells in systemic immunity protective against primary and secondary challenges with Trypanosoma cruzi.

In general, gamma interferon (IFN-gamma)-producing CD4(+) Th1 cells are important for the immunological control of intracellular pathogens. We previously demonstrated an association between parasite-specific induction of IFN-gamma responses and resistance to the intracellular protozoan Trypanosoma cruzi. To investigate a potential causal relationship between Th1 responses and T. cruzi resistance, we studied the ability of Th1 cells to protect susceptible BALB/c mice against virulent parasite challenges. We developed immunization protocols capable of inducing polarized Th1 and Th2 responses in vivo. Induction of parasite-specific Th1 responses, but not Th2 responses, protected BALB/c mice against virulent T. cruzi challenges. We generated T. cruzi-specific CD4(+) Th1 and Th2 cell lines from BALB/c mice that were activated by infected macrophages to produce their corresponding cytokine response profiles. Th1 cells, but not Th2 cells, induced nitric oxide production and inhibited intracellular parasite replication in T. cruzi-infected macrophages. Despite the ability to inhibit parasite replication in vitro, Th1 cells alone could not adoptively transfer protection against T. cruzi to SCID mice. In addition, despite the fact that the adoptive transfer of CD4(+) T lymphocytes was shown to be necessary for the development of immunity protective against primary T. cruzi infection in our SCID mouse model, protective secondary effector functions could be transferred to SCID mice from memory-immune BALB/c mice in the absence of CD4(+) T lymphocytes. These results indicate that, although CD4(+) Th1 cells can directly inhibit intracellular parasite replication, a more important role for these cells in T. cruzi systemic immunity may be to provide helper activity for the development of other effector functions protective in vivo.

Inhibition of thymopoiesis of CD34+ cell maturation by HIV-1 in an in vitro CD34+ cell and thymic epithelial organ culture model.

The mechanisms by which HIV-1 affects thymopoiesis were determined by preincubating CD34+ cells or cultured thymic epithelial (CTE) cells with lymphotropic (T-) and monotropic (M-) strains of HIV-1 in an in vitro CTE organ and CD34+ cell coculture model that allows for analysis of development of thymocytes and mature T cells. When purified CD34+ cells were precultured with either T- or M-tropic strains of HIV-1, thymopoiesis was impaired in a two-week coculture manifested by decreased cell number of thymocytes generated. However, the percentages of thymocyte subpopulations were comparable to control uninfected cocultures. Furthermore, HIV infection of thymocytes was predominantly observed in the CD44+CD3- population. However, in a four-week coculture experiment, HIV infection and depletion of more mature thymocytes were also observed. When CTE cells were preincubated with T- and M-tropic strains of HIV before addition of CD34+ cells, the number of thymocytes and subpopulations of thymocytes at early and later stages of maturation were markedly decreased. Furthermore, CD34+ and CD44+CD3- cells become HIV-infected. In summary, HIV-1 infection inhibited thymocyte maturation at early stages of thymocyte maturation CD44+CD25-CD3-. In addition, HIV also depleted later stages of CD4+ thymocyte subpopulations.

Thymosin-alpha1 stimulates maturation of CD34+ stem cells into CD3+4+ cells in an in vitro thymic epithelia organ coculture model.

The effect of thymosin-alpha1 on thymopoiesis is largely unknown. Thymosin is found in the cortical and medullary thymic epithelia, as well as in nurse cells; thus, it is hypothesized that thymosin may affect both early and late stage of thymocyte maturation. In this study, the effect of thymosin-alpha1 on thymopoiesis was determined by coculturing in vitro CD34+ stem cells (SC) with allogeneic cultured thymic epithelia fragments (CTEF) for 1-4 weeks and analyzing T-cell maturation by flow cytometry. Thymosin-alpha1 significantly enhanced the cell number (e.g., proliferation) of mononuclear cells obtained at 2 and 4 weeks of the SC-CTEF cocultures (P < 0.01 and < 0.05, respectively). In particular, thymosin-alpha1 stimulated expression of CD3+ cells at 3 and 4 weeks (P < 0.05). The predominant subpopulation increased by thymosin stimulation was single positive mature CD4+ cells, which was confirmed to occur within the SC-CTEF thymic organ tissue by laser confocal immunofluorescence microscopy. Thymosin stimulation tended to enhance IL-7 synthesis, critical cytokine in the maturation of thymocytes. In summary, this is the first study to demonstrate that thymosin-alpha1 enhanced thymopoiesis of CD34+ stem cells in humans using an in vitro model of differentiation using stem cells and cultured thymic epithelial fragments cocultures. Furthermore, the thymosin significantly increased expression of CD3+4+ T cells.

Bacille Calmette-Guérin vaccination enhances human gamma delta T cell responsiveness to mycobacteria suggestive of a memory-like phenotype.

Bacille Calmette-Guérin (BCG) immunity can be studied as one experimental model for mycobacterial protective immunity. We have used flow cytometry to investigate human T cell subsets induced by BCG vaccination. PBMC harvested from BCG-vaccinated individuals and controls were stimulated with mycobacterial Ags, and the T cell subsets present after 7 days of in vitro expansion were characterized. The most dramatic expansions induced by mycobacterial Ags were detected in gamma delta T cells. The gamma delta T cell expansions measured after in vitro stimulation with mycobacterial Ags were significantly greater in BCG responders compared with nonsensitized controls, indicating that BCG vaccination induced gamma delta T cell activation associated with enhanced secondary responses. The majority of gamma delta T cells induced by BCG vaccination were gamma 9+ delta 2+ T cells reactive with isoprenyl pyrophosphates. Coculture with CD4+ T cells induced optimal gamma delta T cell expansion, although IL-2 alone could provide this helper function in the absence of CD4+ T cells. Gamma delta T cells were found to provide helper functions for mycobacterial specific CD4+ and CD8+ T cells as well, demonstrating reciprocal stimulatory interactions between gamma delta T cells and other T cell subsets. Finally, prominent mycobacterial specific gamma delta T cell expansions were detected in a subset of unvaccinated controls with evidence for prior sensitization to mycobacterial lysates (elevated mycobacterial specific lymphoproliferative responses). These latter findings are consistent with the hypothesis that exposure to atypical mycobacteria or related environmental Ags may induce gamma delta T cells cross-reactive with Ags present in the Mycobacterium tuberculosis complex. Our results suggest that gamma delta T cells may be capable of developing a memory immune-like phenotype, and therefore might be important targets for new vaccines.

Expression of macrophage markers by a population of T cells obtained from synovial fluid of a subgroup of patients with juvenile rheumatoid arthritis.

OBJECTIVE: To characterize distinctive lymphoid cell populations in the synovial fluid (SF) of patients with juvenile rheumatoid arthritis (JRA) that have the specific ability to display monocytic markers when cultured in vitro. METHODS: Mononuclear cells obtained from SF of patients with JRA and depleted of adherent macrophages were cultured in vitro in RPMI 1640 medium supplemented with only fetal calf serum (FCS). Phenotypic evaluation of these cells was by flow cytometry and immunohistochemical analysis was by specific fluorochrome labeled antibodies. RESULTS: T cells from a JRA subgroup displayed some typical macrophage attributes, i.e., abundant cytoplasm, adherence to plastic, and phagocytosis of latex beads when cultured in vitro. These cells have the ability to survive in culture for several weeks in RPMI 1640 medium containing only 10% FCS. The macrophage-like T cells rosetted with sheep red blood cells and proliferated when stimulated with phytohemagglutinin or anti-CD3, indicating functional T cell responses. CONCLUSION: Our data indicate that a population of T cells obtained from the SF of a subgroup of patients with JRA exhibited characteristics of macrophages, yet retained their CD3 and T cell receptor expression. Whether this promiscuous behavior is caused by malignant transformation of lymphoid precursor cells or is induced by the concerted effect of a myriad of cytokines and growth factors present in the SF remains unknown. The presence of these cells in the SF of 2 patients with JRA with different onset types raises the question of their function and significance in an autoimmune disorder such as JRA.

Development of a method of thymocyte differentiation of bone marrow-enriched CD34+CD38- cells in postnatal allogeneic cultured thymic epithelia to evaluate immunodeficiency disorders.

An in vitro model of CD34+CD38- stem cell (SC) differentiation in postnatal cultured thymic epithelia fragment (CTEF) cocultures is described. Sequential phenotypic analysis of the progeny of the SC-CTEF demonstrated predominantly thymocytes and minor populations of promyelocytes, monocytes and natural killer cells. Triple-positive CD3+CD4+CD8+, double-positive CD4+CD8+, and mature single-positive CD4+ and CD8+ T cells, which were TCR alpha beta+, were identified indicating normal thymocyte maturation. In kinetic studies, mature single-positive CD4+ T cells increased from 29% of total cells at one week to 54% at four weeks of coculture. These findings demonstrate that coculture of bone marrow-derived SC and allogeneic cultured thymic epithelia in vitro results in continuous normal predominantly thymocyte differentiation. The SC-CTEF cocultures were then infected with two different strains of human immunodeficiency virus. CD4+ thymocytes were markedly decreased. However, inhibition of early thymocyte maturation steps was also suggested by the presence of increased triple-negative and CD44+CD25-CD3-thymocytes and decreased CD44+CD25+ thymocytes. This model system of thymocyte maturation will be useful in the evaluation of primary T cell immunodeficiency disorders, gene therapy of SC and pharmacological augmentation of thymic function.

T cell differentiation/maturation of CD34+ stem cells from HIV-seropositive hemophiliacs in cultured thymic epithelial fragments.

The clinical manifestations of AIDS are predominantly due to the cellular and humoral immune dysfunction caused by HIV infection, and thymic dysplasia caused by HIV infection probably contributes to the T cell lymphopenia. In the present study, T cell differentiation and/or maturation was assessed when enriched CD34+ stem cells (SCs or SC) purified from bone marrow of HIV-seropositive hemophiliacs were cocultured with allogeneic cultured thymic epithelial fragments (CTEFs). When HIV-seropositive hemophiliacs' enriched CD34+ SC were cocultured with allogeneic CTEFs, acquisition of the T cell phenotypic markers CD7, CD2, CD3, CD4, CD8 and T cell receptor for antigen (TCR) alpha beta was observed from cells harvested from the culture media peaking at approximately 28 days. Origin of the differentiated and matured T cells from the CD34+ SC was confirmed by labeling the SC with 5-(and -6)-(((4-chloromethyl)benzoyl)amino)tetra-methyl-rhodamine (CMTMR), a fluorescent cytoplasmic dye, and detecting fluorescence in the differentiated and matured T cell by flow cytometry. In one experiment, CMTMR labeling was omitted and double positive CD4+CD8+ and triple positive CD3+CD4+CD8+ thymocytes were identified. These studies confirmed that thymocyte differentiation/maturation from SC had occurred. In addition, T cells obtained from the CD34+ SC and CTEF cocultures proliferated to phytohemagglutinin stimulation maximally with stem cell donor antigen-presenting cells (APCs) and also proliferated to pooled B cells in a mixed lymphocyte culture (MLC). Furthermore, the T cells produced were tolerant to thymus donor B cell HLA antigens (p < 0.025); though there was slight MLC reactivity to autologous stem cell donor B cell HLA compared to thymic B cells (p < 0.025). These T cells demonstrated positive self-alloreactivity to stem cell HLA antigens in four of nine persons, though decreased compared to pool B cell alloantigens. Furthermore, in three experiments, responsiveness to stem cell donor B cells subsequently disappeared upon further duration of CD34+ SC-CTEF coculture. These studies suggested that CD34+ SC gave rise to accessory cells populating the thymus that contributed to HLA restriction. To further evaluate this hypothesis, two different donors of CD34+ SC were cultured simultaneously with thymic epithelial fragments and MLC reactivity was then examined toward APC of the stem cell donors. In these experiments, T cells responded to stimulation with HLA antigens of the pool B cells and did not respond to thymus donor B cells. In six of eight experiments, the chimeric SC-CTEF T cells did not respond to stimulation with B cells of either stem cell donor. These studies suggest that HLA restriction and tolerance were induced by cells of the stem cell donor as well as the thymic epithelial cell HLA antigens. In summary, these studies demonstrated that HIV-infected hemophiliac bone marrow-derived nonadherent CD34+ SC were capable of differentiating and/or maturing into T cells when cocultured in a normal allogeneic thymic environment. Furthermore, the T cells derived from derived CD34+ SC were capable of differentiating into T cells when cocultured in a normal allogeneic thymic environment, proliferated maximally with APCs from the stem cell donor and were tolerant of thymic HLA class II antigens, and to a lesser degree to stem cell donor B cell HLA antigens.

Infectivity of titered doses of simian immunodeficiency virus clone E11S inoculated intravenously into rhesus macaques (Macaca mulatta).

The macaque infectious dose (MID) of a single-cell clone of simian immunodeficiency virus isolated from a pig-tailed macaque (SIV/Mne clone E11S) was determined in rhesus macaques (Macaca mulatta). Twenty-one macaques were inoculated with 10-fold dilutions of the virus stock (three or four animals per dose). The virologic and clinical status of these animals was monitored for 26 weeks. The 25% MID (MID25) occurred at a 10(5)-fold dilution of the viral stock.

Long-term protection of macaques against high-dose type D retrovirus challenge after immunization with recombinant vaccinia virus expressing envelope glycoproteins.

Recombinant vaccinia virus expressing the envelope proteins of type D retrovirus-Washington (SRV-2/W) was used to immunize macaques against SRV-2 infection. Four immunized macaques which had resisted a prior low-dose challenge were rechallenged with a high dose (10(6) infectious particles) of SRV-2 two years after being immunized. All four non-immunized control macaques became infected, but the four vaccinated animals resisted this intravenous challenge, as determined by the inability to detect SRV-2 in peripheral blood mononuclear cells and by the lack of seroconversion to new viral antigens.

A new case of IgE myeloma.

We report a case of IgE myeloma in a 78-year-old woman who presented with bone pain in the shoulder and hip and progressive weakness. Except for hypercalcemia, routine chemistry values were within normal limits. Hemoglobin was decreased and the leukocyte count slightly increased. Plasma cells were not observed in the peripheral blood. Serum protein electrophoresis showed a monoclonal protein in the beta-globulin fraction. Immunofixation confirmed the presence of an IgE kappa monoclonal protein. A bone marrow biopsy revealed an interstitial and nodular infiltration of abnormal plasma cells comprising 60% of nucleated cells present. Skeletal roentgenograms and bone scans of this patient showed osteolytic lesions and osteopenia of the thoracic and lumbar spine and osteolytic destruction of the right half of the sacrum. Flow-cytometric analysis of mononuclear cells isolated from peripheral blood showed that 15% of the lymphocytes bound IgE. Using cell-surface markers, we identified 45% of the IgE-positive cells as natural killer cells. Similar results have been found in other diseases marked by increased IgE. The clinical, radiological, and laboratory findings for this patient are compared with previously reported cases of IgE and other types of myeloma.

Interleukin-6 and retroperitoneal fibromatosis from SRV-2-infected macaques with simian AIDS.

We investigated the role of Interleukin-6 (IL-6) as an autocrine growth factor for the retroperitoneal fibromatosis (RF) cells present in macaques infected with the simian retrovirus type 2 (SRV-2). Elevated levels of IL-6 were found in serum of SRV-2 antibody-positive macaques, ascites from RF-positive animals, and RF cell line culture media. IL-6 mRNA levels increased approximately five-fold in RF cells incubated with exogenous SRV-2. In RF cells, SRV-2 functions to increase IL-6 mRNA and protein production and presumably serves as autocrine growth factor.

HLA class I antigen expression as a measure of response to antiviral therapy of chronic hepatitis B.

HLA class I antigen expression on peripheral blood mononuclear cells was evaluated by flow cytometry in 21 HBeAg-positive patients with chronic hepatitis B. Measurements were made before, during or after treatment with recombinant interferon-alpha-2b, either given alone or after a 6 wk course of prednisone. Immunohistochemical staining for human leukocyte class I antigen was also evaluated in 28 percutaneous liver biopsy specimens either obtained before or after therapy (N = 27) and during therapy in one instance. The amount of HLA class I antigen on peripheral blood mononuclear cells varied markedly among individual patients, but the overall results indicated that the level of inducible antigen did not correlate with increments of ALT during therapy or with a virological response to therapy. Hepatocyte staining for HLA class I antigen was observed in a minority of biopsy specimens (29%) and also did not appear to predict a response or correlate with the severity of histological disease. These data do not support current theories concerning pathogenetic mechanisms in chronic hepatitis B nor do they suggest that spontaneous display of HLA class I antigen on hepatocytes or interferon-induced expression of these antigens on peripheral blood mononuclear cells is a critical determinant for a response to therapy.

Monoclonal antibody to human osteosarcoma: a novel Mr 26,000 protein recognized by murine hybridoma TMMR-2.

Three murine hybridomas (TMMR-1-3) were developed by repeated immunizations of mice with four different human osteosarcoma cell lines in an alternating sequence of inoculations. The monoclonal antibodies were screened for reactivities to cultured cell lines and tissue sections of osteosarcomas using flow cytometry and immunohistochemical techniques. TMMR-2 is a highly specific antibody (IgG1) that reacted with all 14 osteosarcoma tumors and eight human osteosarcoma cell lines tested, including the established human osteosarcoma cell lines HOS and Saos-2. Benign neoplastic cells from two osteoblastomas, osteoblasts from regions of reparative osteoid formation and neonatal new bone, are also reactive with TMMR-2. TMMR-1 has mesenchymal specificity while TMMR-3, although reactive with osseous differentiated cells, also reacted with mitotic cells of all cell types. Characterization of antigen structure by Western immunoblotting revealed that TMMR-2 reacted with a 100 degrees C heat labile mercaptoethanol-sensitive Mr 26,000 protein, and TMMR-3 recognized a mercaptoethanol-resistant Mr 97,000 protein whereas TMMR-1 reacted with a series of bands from 65,000 to 85,000 molecular weight, all of which were mercaptoethanol sensitive. TMMR-1 and TMMR-2 monoclonal antibodies showed complement-independent inhibition of [3H]thymidine incorporation into DNA, but did not exhibit cytotoxic activity. The results suggest that TMMR-2 is a specific antibody that recognizes an osteoblast/osteocyte surface antigen present in normal, reactive, and neoplastic disorders of bone. The inhibitory effects on DNA synthesis in cultured osteosarcoma cells by TMMR-2 indicate an important cell growth/proliferation role of this surface antigen. These monoclonal antibodies, in combination with other known antibodies, can be used to characterize mesenchymal cell surface antigenic structure and differentiation.

Mesenchymoproliferative disorders (MPD) in simian AIDS associated with SRV-2 infection.

We have observed several mesenchymal proliferative disorders (MPD) in macaques with SAIDS associated with SRV-2 infection. Retroperitoneal and subcutaneous fibromatosis, progressive fibrovascular proliferation, mimicking Kaposi's sarcoma, were seen in 165 macaques. Three obliterative fibrointimal proliferative arteriopathies and one congenital pulmonary sequestration with extensive MPD were observed in SRV-2 positive monkeys. Continuous cell lines were established and SRV-2 was identified in all tissues and cell lines. Immunophenotyping of the cultured cells showed heterogeneous mesenchymal cells. Xenograft and allograft transplantation of cultured cells produced MPD lesions in the recipients. The data suggest that SRV-2 plays an important role in the etiopathogenesis of MPD in macaques.

T cells in ventricular assist device patients.

Levels of T lymphocytes were measured in 20 consecutive patients, 18 men and two women, supported with ventricular assist devices or an artificial heart. Indications for support were bridge to transplantation (n = 10), postcardiotomy cardiogenic shock (n = 8), and acute myocardial infarction shock (n = 2). Control levels were from healthy volunteers not undergoing cardiac operation. Preoperatively, numbers of total lymphocytes and subclasses CD3, CD4, and CD8, as well as the interleukin-2 receptors (IL2R), were the same as controls (cells/microliters): lymphocytes, 1,940; CD3, 1,413 +/- 410; CD4, 894 +/- 318; CD8, 490 +/- 185; IL2R, 96. From implant to postoperative day 5, levels were below control values (p less than 0.001), reaching a nadir on postoperative day 2 (lymphocytes, 896 +/- 599; CD3, 489 +/- 267; CD4, 309 +/- 207; CD8, 183 +/- 107; IL2R, 43 +/- 47). Data from 10 patients (group 1) who survived (four weaned from cardiopulmonary bypass, six transplanted) were compared with those from 10 patients (group 2) who died of multiorgan failure, sepsis, or both. From preimplant through postoperative day 6, levels did not differ between groups. However, from postoperative day 7 to the last day of ventricular support (group 1, 24-90 days; group 2, 7-29 days), group 1 levels (lymphocytes, 2,364 +/- 618; CD3, 1,825 +/- 553; CD4, 1,013 +/- 187; CD8, 796 +/- 402) were significantly above (p less than 0.01) group 2 levels (lymphocytes, 1,290 +/- 463; CD3, 746 +/- 295; CD4, 534 +/- 253; CD8, 221 +/- 106). These data indicate that lymphocytes and particularly T cells 1) decrease after ventricular assist device insertion, reaching a nadir at postoperative day 2, 2) return to control values after patients whose clinical status improves, and 3) remain low in severely ill patients. T-cell depression in ventricular assist device patients is related to the severity of the patient's condition rather than the presence of the device.

Flow cytometric indirect immunofluorescence assay with high sensitivity and specificity for detection of antibodies to human immunodeficiency virus (HIV).

A flow cytometric immunofluorescence assay (FIFA) was developed to detect antibodies to human immunodeficiency virus (HIV) using live cell indirect immunofluorescence and analysis by flow cytometry. A panel of 107 sera, previously tested for anti-HIV antibody with the Abbott Enzyme-Linked Immunosorbent Assay test and Western blot (WB), was rescreened by FIFA. Antibodies were tested on HIV-infected and uninfected H9 cells in the FIFA. Although ELISA results indicated seven false positive results by comparison with the WB, 46 of 46 FIFA positive results tested WB positive and 61 of 61 FIFA negative results were WB negative. The results of FIFA showed 100% sensitivity and 100% specificity compared with WB. This rapid, quantitative, relatively easy assay makes FIFA an alternate confirmatory test for the presence of HIV antibodies.

Monoclonal antibodies to type D retrovirus (SRV-2).

Monoclonal antibodies (MoAbs) to the major gag core protein p27 and a viral protein p44 of type D retrovirus (SRV-2) were produced and used in the detection of SRV-2 antigens in infected Raji cells and in tissues from macaques with simian acquired immunodeficiency syndrome (SAIDS) and retroperitoneal fibromatosis (RF). Anti-p44 MoAb showed inhibition of syncytium formation by both SRV-1- and SRV-2-infected Raji cells.

Medical evaluation of subjects with known body levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Forty-one persons with a history of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure and measured adipose tissue TCDD levels were evaluated for potential health effects. No pattern of clinical abnormalities emerged related to TCDD levels.

A medical follow-up of the health effects of long-term exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The human health effects of long-term exposure to low levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have not been well established. The results of a prior study showed that persons exposed to TCDD had depressed cell-mediated immunity, and 18 of 51 persons had anergy or relative anergy on skin testing. This paper presents the results of a medical follow-up on participants who were reported to be anergic or relatively anergic in the earlier study. None of the participants in the follow-up study was anergic, and only one exposed and one unexposed participant were relatively anergic. Several technical and biological possibilities for the difference in results of the two studies are presented. The possibility that recovery from the effects of TCDD exposure caused the differing results is the least plausible explanation for the changes in the skin test results.