Suppression of Staphylococcus aureus Cowan I-induced immunoglobulin synthesis in vitro: discrimination between the presence of suppressor T cell precursors and effectors.

In co-cultures with control cells lymphocytes obtained from some patients with hypogammaglobulinaemia can suppress PWM but not S. aureus Cowan I-induced polyclonal immunoglobulin production. When such co-cultures were stimulated at the same time with both mitogens, the response was greatly suppressed. This phenomenon was further studied in cultures of lymphocyte populations isolated from healthy donors. It was found that suppressor T lymphocytes activated by PWM in cultures co-stimulated with Con A, with high T:B cell ratio, or with an increased proportion of OKT8+ T cells can suppress the S. aureus-induced response. In contrast, under the same conditions S. aureus did not activate suppressor cells. Moreover, in cultures stimulated with this polyclonal B-cell activator OKT8+ lymphocytes could serve as helper cells.     

Expansion of peripheral CD8+ CD28- T cells in response to Epstein-Barr virus in patients with rheumatoid arthritis

OBJECTIVE: To investigate control of Epstein-Barr virus (EBV) infection in rheumatoid arthritis (RA) by comparing the frequency phenotypes and function of peripheral CD8+ EBV-peptide antigen-specific T cells in patients with RA and healthy longterm carriers of EBV. METHODS: The frequency of interferon-g (IFN-g)-producing HLA-A2 or HLA-B8-restricted EBV-reactive CD8+ T cells in peripheral blood mononuclear cells (PBMC) from 49 RA patients and 26 healthy EBV carriers was evaluated in Elispot assays with 12 lytic/latent peptide epitopes. Direct staining with HLA-peptide tetramers containing 3 of these peptides was performed for comparison. The phenotype and function of these T cells was determined by FACS and cytotoxicity testing. RESULTS: IFN-g production patterns in Elispot assays revealed that EBV-specific CD8+ T cells were directed predominantly against the lytic epitopes A2/GLC and B8/RAK and to a minor extent to all the other lytic and latent epitopes tested, with no significant differences of the frequencies in patients and controls. However, although similar frequencies of CD8+ T cells stained with A2/GLC or B8/RAK tetramers in both groups, the fraction of A2/GLC or B8/RAK-reactive T cells producing IFN-g in response to specific peptide antigen was significantly lower in RA patients than controls. The A2/GLC or B8/RAK tetramer-positive T cells were also substantially enriched in CD28-CD27- T cells of a late-differentiated phenotype in RA patients but not in controls. CONCLUSION: RA patients show clonal expansion of dysfunctional, terminally differentiated CD8+ EBV-specific T cells in their T cell responses to immunodominant lytic peptide EBV epitopes, which could be a sign of specific impairment of virus-host interactions in RA.     

Inhibitory and stimulatory effects of Pseudomonas aeruginosa pyocyanine on human T and B lymphocytes and human monocytes.

Pyocyanine, a pigment produced by Pseudomonas aeruginosa, has dual dose-dependent stimulatory as well as inhibitory effects on immune responses in vitro as measured by DNA synthesis of human T and B lymphocytes, interleukin-2 (IL-2) production by human T lymphocytes, immunoglobulin production by human B lymphocytes, and monokine production by human monocytes. In general, stimulatory activity was found at low concentrations of pyocyanine, whereas high concentrations of the pigment resulted in an inhibition of responses. At a pyocyanine concentration of 0.1 micrograms/ml or less the proliferation of T and B lymphocytes was enhanced, but at 0.5 micrograms/ml it was suppressed. IL-2 production by T lymphocytes was enhanced at concentrations up to 0.5 micrograms/ml but totally inhibited at 1.0 micrograms/ml. The differentiation of B lymphocytes to become immunoglobulin-producing cells was also enhanced in the presence of low doses of pyocyanine, whereas secretion of immunoglobulin by B lymphocytes was suppressed at all concentrations of pyocyanine. In contrast to the dual effects of pyocyanine on lymphocyte response, lipopolysaccharide-induced IL-1 and tumor necrosis factor release by monocytes was markedly enhanced by low as well as high concentrations of pyocyanine. From these results we conclude that this property of pyocyanine may lead to suppression of specific defense mechanisms and enhance harmful inflammatory reactions of the host during infection with Pseudomonas aeruginosa.     

The cellular immune status in normal subjects, patients with and without neoplasms]

The distribution of lymphatic subpopulations in the peripheral blood of patients with malignant solid tumors has been studied in two steps. Firstly, it was investigated whether there are changes in the distribution of blood lymphoid cell populations in tumor patients (n = 101) compared to normal individuals (n = 39) and whether there is a correlation between the distribution pattern and the clinical stage of the disease. There was found a significant reduction of T-lymphocytes in patients with cancer, which was marked in the advanced tumor disease (n = 34). In a further step the influence of curative tumor-resection on the lymphatic subpopulations was studied, when 26 operated tumor patients were compared with 23 operated patients without neoplasia. In the group with non-malignant diseases there could not be found a significant pre- and postoperative difference concerning the T- and B-lymphocyte counts. Tumor patients showed after resection of the tumor a significant increase of the absolute and relative number of preoperatively reduced T-lymphocytes. The pathophysiological possibilities for the phenomena of a reversible reduction of T-lymphocytes by the curative resection of the tumor are discussed.     

Effects of systemicin vivo interleukin-2 (IL-2) reconstitution in patients with acquired immune deficiency syndrome (AIDS) and AIDS-related complex (ARC) on phenotypes and functions of peripheral blood mononuclear cells (PBMC)

In the context of a clinical phase I/II therapy study with recombinant interleukin-2 (rIL-2), we monitored immunological alterations in four patients with acquired immune deficiency syndrome (AIDS) and three patients with AIDS-related complex (ARC). By determining the surface phenotypes andin vitro functions of peripheral blood mononuclear cells (PBMC) before, during, and after treatment with rIL-2, we observed transient changes in all important leukocyte subpopulations, a minor restoration of immune reactivityin vitro, and an improvement in skin reactivityin vivo. In particular, we found (i) a transient increase in C3b receptor-mediated monocyte activation in ARC patients; (ii) no influence of therapy on the otherwise intact LPS-induced interleukin-1 productionin vitro; (iii) in some patients a transient corrective influence on the high pretherapeutic immunoglobulin secretion of B cells and their nonresponsiveness to pokeweed mitogen; (iv) low T-cell responses to soluble antigens and alloantigens, which were partially restored during rIL-2 treatment in ARC patients and in one AIDS patient; (v) defective NK activity in PBMC of two AIDS patients, which was found to be restored when measured at the end of rIL-2 therapy; and (vi) a rather constant phenotypic pattern of PBMC in each patient during therapy except for the decreasing proportion of OKT9-positive lymphocytes in AIDS patients, the increasing proportion of Leu8^–Leu3a⁺ lymphocytes in all patients, and in particular, the transient significant decrease in the Leu7⁺/OKT3⁺ ratio, which pretherapeutically was very high in AIDS patients (0.78±0.21) and high in ARC patients (0.48±0.06) as compared to healthy controls (0.18±0.08).Dedicated to Prof. Dr. Dr. h. c. Otto Westphal, who continuously supported and encouraged cooperation of basic and clinical immunologists.     

Langzeitsubstitution von Thrombocyten bei Patienten mit Panmyelopathie und schwerer Thrombocytopenie

Zusammenfassung Bei 10 stark alloimmunisierten Patienten mit Panmyelopathie und schwerer Thrombocytopenie wurden Thrombocyten von im Kreuztest negativen verwandten und nichtverwandten Spendern übertragen. In fast allen Fällen konnten signifikant längere Halbwertszeiten der transfundierten Thrombocyten im Vergleich zu unausgewählten Spendern beobachtet werden. Durch Bestimmung der HL-A-Allele bei verwandten Spendern fand sich eine Beziehung zwischen dem Grad der genetischen Übereinstimmung und der Überlebenszeit der Blutplättchen. Dies trifft auch teilweise für nichtverwandte, im Kreuztest negative Spender bezüglich der phänotypischen Differenz zu. Thrombocytopenische Blutungen können damit auch über lange Zeit verhindert werden.Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Development of an MHC-class I peptide selection assay combining nanoparticle technology and matrix-assisted laser desorption/ionisation mass spectrometry

Human leukocyte antigen (HLA)-bound peptides are central for recognition of infected/transformed cells by T cells, and have formed the basis for many immunotherapy strategies. Epitopes from a given protein sequence (e.g. from viral proteins or oncoproteins) can be predicted by algorithms, as individual HLA receptors bind peptides through defined binding motifs. Peptides with the highest predicted binding score are then normally tested for their binding ability in binding assays. However, with the assays already established, only one peptide can be tested for binding per assay. This is certainly not a reflection of the in vivo situation, where several peptides generated via the major histocompatability complex (MHC)-class I processing pathway compete for HLA-receptor binding. Here, we describe the development of a method that can mimic the competition between multiple peptides for binding to a single HLA receptor molecule. We used silica nanoparticles with immobilised HLA-A2 complexes to screen HLA-A2 binder-peptides out of a known peptide mixture. The washed beads were analysed for selectively bound peptides by matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry. The advantage of the system is that the bound peptides can be unambiguously identified without any prior modification (e.g. radioactive or fluorescence labelling), even from complex peptide mixtures.