Human alveolar macrophages present antigen ineffectively due to defective expression of B7 costimulatory cell surface molecules

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.

CD28-CD80/CD86 interactions in testicular immunoregulation

The expression of two accessory molecules on antigen-presenting cells (APC), the CD80/ B7-1 and CD86/B7-2 antigens, was studied in the testis of normal and non-obese diabetic (NOD) mice. In addition, the effect of CD28 stimulation on suppression of lymphocytes by testicular products was investigated. The testes of 4-week old NOD mice or normal BALB/c mice and the testis of 17-21-week old BALB/c mice contained no CD80 or CD86 expressing cells. In contrast, CD80+ and CD86+ cells were present in the testis of 14-22-week old NOD mice. The CD80+ cells and most of the CD86+ cells were CD11b/CD18 negative. There were some CD11b/CD18+ cells that expressed CD86 weakly. The CD80+ and CD86+ cells were often located adjacent to the vessel walls where a leukocyte not expressing CD80 or CD86 had attached to the endothelium. Some CD80+ and CD86+ cells were present among the interstitial cells. The CD80 and CD86 antigens could not be observed in the same cells as judged from stainings in parallel sections. Stimulation of ConA- or anti-CD3 epsilon-primed peripheral blood or spleen lymphocytes with anti-CD28 was able significantly to antagonize the growth-inhibitory effect of the M(r) > 5 K fraction of testis extracts, but could not abolish it with increasing concentrations of testis extract. The results suggest that T lymphocytes can not be activated locally in the testis of BALB/c and young NOD mice because of the absence of the necessary CD28 ligands, CD80 and CD86, from the APCs and because of the suppression of T lymphocytes by the testicular products. In the testis of older diabetic NOD mice lymphocyte activation may occur because the testes of these mice contain CD80+; CD11b/CD18-, CD86+; CD11b/CD18+ and CD86+; CD11b/CD18- cells and therefore, CD28 co-stimulation, which can antagonize the suppressive effect of testis extract, may occur. The possibilities for clonal anergy in testicular immunoregulation are discussed.

Immune therapy with macrophages: present status and critical requirements for implementation

Adoptive transfer of activated macrophages has been validated in animal experimental tumor models; clinical trials are ongoing (70 patients up to now). The mechanisms involved are reviewed as well as improved and standardized procedures for macrophage differentiation and activation. New developments including specific Ag presentation and gene therapy are discussed.

Nuclear factor-kappa B is activated in alveolar macrophages from patients with acute respiratory distress syndrome

OBJECTIVE

The expression of proinflammatory cytokines is rapidly increased in experimental models of the acute respiratory distress syndrome (ARDS), in patients at risk for ARDS, and in patients with established ARDS. Because multiple cytokines are present in bronchoalveolar lavage fluid, a common, proximal activation mechanism may operate in these settings. The proinflammatory cytokines whose expression is increased in the lungs of patients with ARDS have binding sequences in their enhancer/promoter regions for transcriptional regulatory proteins, such as nuclear factor-kappa B (NF-kappa B), nuclear factor-IL6 (NF-IL6), cyclic adenosine monophosphate responsive element binding protein, serum protein-1, and activating protein-1. To test the hypothesis that activation of one or more of these nuclear transcriptional regulatory factors might provide a common mechanism for the simultaneous expression of multiple cytokine genes in the setting of ARDS, we measured activation of these factors in alveolar macrophages from patients with ARDS and from controls.

DESIGN

Prospective, clinical study.

SETTING

Medical and surgical intensive care units at a university hospital and a county hospital.

PATIENTS

Twelve patients, six with established ARDS and six control patients without lung injury.

INTERVENTIONS

Patients with ARDS and controls underwent fiberoptic bronchoscopy and bronchoalveolar lavage. Alveolar macrophages were isolated from lavage fluid and the nuclear proteins were extracted. Activation of transcriptional factors NF-kappa B, NF-IL6, cyclic adenosine monophosphate responsive element binding protein, activating protein-1, and serum protein-1 was determined using an electrophoretic mobility shift assay, followed by densitometry of the autoradiographed gels.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in gender, age, tobacco smoking, Acute Physiology and Chronic Health Evaluation II score, quantity of lavage fluid, or number of alveolar macrophages in lavage specimens in the patient groups. Acute Lung Injury score and the Pao2/Fio2 ratio differed significantly between controls and ARDS patients: 0.46 +/- 0.17 vs. 2.74 +/- 0.14 (p < .0001) and 310 +/- 45 torr (41.3 +/- 6.0 kPa) vs. 150 +/- 11 torr (21.3 +/- 1.5 kPa) (p < .006), respectively. The mean Fio2 of the control patients was not significantly different from the mean Fio2 of ARDS patients: 0.47 +/- 0.11 vs. 0.55 +/- 0.6 (p = .53). Patients with ARDS had significantly (p < .02) increased activation of NF-kappa B in alveolar macrophages compared with patients without the syndrome. There was no evidence of increased activation of the transcriptional factors activating protein-1, serum protein-1, NF-IL6, or cyclic adenosine monophosphate responsive element binding protein in alveolar macrophages from ARDS vs. control patients.

CONCLUSIONS

These experiments demonstrated increased in vivo activation of the nuclear transcriptional regulatory factor NF-kappa B (but not NF-IL6, cyclic adenosine monophosphate responsive element binding protein, activating protein-1, or serum protein-1) in alveolar macrophages from patients with ARDS. Because binding sequences for NF-kappa B are present in the enhancer/promoter sequences of multiple proinflammatory cytokines, activation of NF-kappa B may contribute to the increased expression of multiple cytokines in the lung in the setting of established ARDS.

Interferon-gamma and interleukin-10 have cross-regulatory roles in modulating the class I and class II MHC-mediated presentation of epitopes of Listeria monocytogenes by infected macrophages

IFN-gamma is an important cytokine in resistance to infection with Listeria monocytogenes, and interleukin 10 is known to exacerbate infection with Listeria and other intracellular pathogens. We examined the effects of these cytokines on antigen presentation by macrophages infected with live Listeria. Listeriolysin O, a hemolysin secreted by Listeria, is an immunodominant antigen presented by both class I and class II MHC on infected cells. Thioglycollate-elicited macrophages were pretreated with exogenous IFN-gamma, IL-10, or both cytokines overnight, infected with bacteria, and then fixed. Epitope-specific, MHC-restricted, T cell hybridomas were then added to detect the presentation of the class I or class II ligand. We found that IFN-gamma enhanced the presentation of both the class I and class II epitopes and IL-10 strongly inhibited the presentation of both ligands. The degree of inhibition of presentation caused by IL-10 was dose dependent. IL-10 was also able to inhibit the presentation of exogenously added class II-binding peptide but had a less dramatic effect on the presentation of the added class I-binding polypeptide epitope. Flow cytometric analysis of expression of class I and class II on treated macrophages demonstrated that the inhibitory effect of IL-10 on antigen presentation was not due to significant downregulation of MHC expression. This loss of antigen presentation was also not due to downregulation of the costimulatory molecule, B7-2. We have found that IFN-gamma and IL-10 have opposing immunoregulatory effects on the presentation of antigens derived from an intracellular pathogen and that the class I vs. class II-mediated presentation of antigens is differentially regulated by IL-10.

Intranasal and intramuscular proteosome-staphylococcal enterotoxin B (SEB) toxoid vaccines: immunogenicity and efficacy against lethal SEB intoxication in mice

Intranasal or intramuscular (i.m.) immunization of mice and i.m. immunization of rabbits with formalinized staphylococcal enterotoxin B (SEB) toxoid in saline elicited higher anti-SEB serum immunoglobulin G (IgG) titers when the toxoid was formulated with proteosomes. In addition, intranasal immunization of mice with this proteosome-toxoid vaccine elicited high levels of anti-SEB IgA in lung and intestinal secretions, whereas the toxoid without proteosomes did not. Two i.m. immunizations with proteosome-toxoid plus alum also induced higher murine serum responses than alum-adjuvanted toxoid without proteosomes. Furthermore, proteosome-toxoid delivered intranasally in saline or i.m. with either saline or alum afforded significant protection against lethal SEB challenge in two D-galactosamine-sensitized murine models of SEB intoxication, i.e., the previously described i.m. challenge model and a new respiratory challenge model of mucosal SEB exposure. Efficacy correlated with the induction of high serum levels of anti-SEB IgG. In contrast, intranasal or i.m. immunization with toxoid in saline without proteosomes was not significantly protective in either challenge model. Proteosome-toxoid plus alum given i.m. also elicited more significant protection against respiratory challenge than the alum-adjuvanted toxoid alone. The capacity of proteosomes to enhance both i.m. and intranasal immunogenicity and efficacy of SEB toxoid indicates that testing such proteosome-SEB toxoid vaccines in the nonhuman primate aerosol challenge model of SEB intoxication prior to immunogenicity trials in humans is warranted. These data expand the applicability of the proteosome mucosal vaccine delivery system to protein toxoids and suggest that respiratory delivery of proteosome vaccines may be practical for enhancement of both mucosal and systemic immunity against toxic or infectious diseases.

Intransal or intragastric immunization with proteosome-Shigella lipopolysaccharide vaccines protects against lethal pneumonia in a murine model of Shigella infection

Mice immunized intransally or intragastrically with proteosome vaccines containing either Shigella sonnei or S. flexneri 2a lipopolysaccharide were protected against lethal pneumonia caused by homologous organisms in an experimental murine intranasal challenge model of Shigella infection. Histopathological analysis demonstrated that immunization also protected against the progressive lesions resulting from invasion of the pulmonary mucosa by S. sonnei. These data show that mucosal proteosome-lipopolysaccharide vaccines can protect against lethal bacterial pneumonia and indicate that such vaccines are promising candidates for protection against intestinal shigellosis.