Tore Godal

Human T-cell clones recognize a major M. leprae protein antigen expressed in E. coli

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. As with other intracellular parasites, protective immunity is dependent on T cells and cell-mediated immunity1. In animal models, immunization with killed armadillo-derived M. leprae elicits strong T-cell responses, delayed-type hypersensitivity and protection against viable challenge2–5. We have recently shown that killed M. leprae can induce delayed-type hypersensitivity in healthy human volunteers6. Identification of the M. leprae antigens that are recognized by T cells and may be involved in protection has been hampered by the inability to cultivate the organism in vitro and by difficulties in antigen purification from limited quantities of armadillo-derived bacillus. Because genes for the major protein antigens of M. leprae as seen by mouse monoclonal antibodies have been isolated7,8, it has become possible to test whether these individual antigens are recognized by T cells. We screened crude λ gtll phage lysates of Escherichia coli containing individual M. leprae antigens using M. leprae-specific T-cell clones isolated from M. leprae-vaccinated volunteers. Using this method, we find that nearly half of the M. leprae-specific T-cell clones are stimulated to proliferate by lysates containing an epitope of a M. leprae protein of relative molecular mass 18,000 (18K).

Transforming growth factor type β (TGF β) inhibits G1 to S transition, but not activation of human B lymphocytes☆

Abstract Type β transforming growth factor (TGF β) is a polypeptide that may influence the growth of a variety of cell types in a positive or negative fashion. In this study we show that TGF β markedly inhibits DNA synthesis in normal and neoplastic human B lymphocytes stimulated to proliferate with anti-immunoglobulins and B-cell growth factor (BCGF). Although TGF β was needed during the initial 12 h of the culture to promote optimal inhibition, we found that it had little or no effect on several early to intermediate parameters of cell activation ([Ca 2+ ] i increase, c- myc mRNA increase, cellular enlargement, RNA increase, and the increase in the expression of the 4F2 activation antigen). In contrast, TGF β almost completely blocked the induction of transferrin receptor expression, which normally occurs in the late G 1 phase of the cell cycle. Therefore, we conclude that TGF β treatment leads to arrest of the cells in the middle to late G 1 phase, prior to transferrin receptor expression.

Human B-Cell Neoplasms in Relation to Normal B-Cell Differentiation and Maturation Processes

Publisher Summary This chapter reviews the functional studies on human neoplasias particularly emphasizing on B-cell neoplasms, thus limiting to the B-cell compartment. The diagnostic systems in human oncology are based on the relationship between neoplastic cells and their normal counterparts. The progress in immunology, at the basic level as well as at the clinical methodological level, has allowed reassessment to take place with regard to neoplasms associated with lymphoid tissues. Such studies have shown that among non-Hodgkin lymphomas (NHL) and chronic lymphocytic leukemia (CLL), the great majority of neoplasms have B-cell characteristics. The only known function of the B-cell compartment is the production of antibodies. Thus, in all the aspects discussed in the chapter, emphasis has been on Ig-related phenomena. However, the chapter also discusses biological processes taking place in the B-cell compartment. These include a number of fascinating phenomena such as generation of diversity, allogeneic exclusion, isotype light-chain restriction, clonal “abortion”, isotype coexpression and switch, B-cell proliferation, affinity maturation, and antibody production and secretion.

Reversal by Interleukin-2 of the T Cell Unresponsiveness of Lepromatous Leprosy to Mycobacterium Leprae

In some subjects Mycobacterium leprae causes disseminated (lepromatous) disease. Such subjects show both in vivo and in vitro deficient T cell responses to M. leprae, but not to other antigens. We have recently shown that lepromatous peripheral blood mononuclear cells (PBMC) failed to produce interleukin 2 (IL-2) in response to M. leprae and that T cell-conditioned media (TCM) can reverse the T cell unresponsiveness in a majority of lepromatous leprosy patients (Haregewoin et al. 1983). Here we show that highly purified and recombinant IL-2 had effects similar to TCM. On the other hand, lepromatous PBMC produced IL-1, and IL-1 had no restorative effect. These findings provide further evidence that the unresponsiveness in lepromatous leprosy often results from a deficiency in IL-2 production. After initial stimulation with TCM + M. leprae, lepromatous PBMC could be restimulated with M. leprae alone, providing clear evidence that M. leprae-reactive lymphocytes were generated in the presence of TCM. The present findings are discussed in relation to the possible mechanisms involved in the failure of IL-2 production. If our findings can be reproduced in vivo, IL-2 may offer a novel approach to therapy in lepromatous leprosy.

Monoclonal antibodies against mycobacterial antigens

The World Health Organization (WHO) scientific working groups on the Immunology of Leprosy (IMMLEP) and Tuberculosis (IMMTUB) recently organized two international workshops designed to characterize the specificity and reaction patterns of approximately 55 murine monoclonal antibodies (mAbs) which had been raised against Mycobacterium leprae or Mycobacterium tuberculosis and submitted to the IMMLEP and IMMTUB monoclonal antibody banks.

Distinct Effects of γ Interferon on Human B‐Lymphocyte Precursor Cell Lines

The effect of γ interferon (IFN‐γ) on proliferation and antigenic characteristics of cell lines belonging to the B‐cell progenitor compartment was studied. We observed a selective effect of recombinant IFN‐γ but not IFN‐α on proliferation of the B‐precursor cell lines Reh and KM3. On day 4, after addition of 400 μ/ml IFN‐γ the [3H]thymidine uptake in these cells was reduced to 60% and 45% respectively, while no effect of IFN‐γ was evident on the proliferation of the more mature B‐cell lines Raji. Ramos, B85, and Daudi. On the other hand, both Reh and Ramos showed induction of major histocompatibility complex (MHO class 1 antigen expression in response to 400 μ/ml IFN‐γ. In contrast to 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA), IFN‐γ did not induce increased MHC class II antigen expression on Reh cells. Taken together, our results indicate that IFN‐γ fulfils distinct functions at different levels in the development of B cells.

Heterogeneity of degradation of B-cell endocytosed monoclonal antibodies reacting with different sIgM epitopes.

The degradation of a panel of monoclonal antibodies (MoAb) bound to surface IgM (sIgM) was studied in three human Burkitts lymphoma cell lines. The panel included MoAb that recognize several distinct epitopes associated with the F(cμ)5 domain, the cμ2 domain, and δ or λ light chains. The amount of degraded MoAb and the rate of their degradation varied considerably between the various antibodies. Properties of MoAb such as avidity or ability to cross‐link sIgM did not significantly influence their degradation. The most consistent correlation between rate of degradation and MoAb used was the location of the epitope recognized by the individual MoAb. Thus, 7 out of 8 anti‐light chain MoAb were degraded at a higher rate than 5 out of 5 anti‐F(cμ)5 MoAb. One anti‐cμ2 MoAb was degraded at a rate similar to the majority of anti‐light chain MoAb. The intracellular transport of an anti‐δ light chain MoAb and an anti‐F(cμ)5 MoAb was studied in detail by subcellular fractionation in sucrose gradients. We found that the anti‐δ light chain MoAb was transported more rapidly to lysosomes than the anti‐F(cμ)5 MoAb, showing that they were sorted differently intracellularly.

The role of interleukin-2 (IL-2) in the specific unresponsiveness of lepromatous leprosy to Mycobacterium leprae: studies in vitro and in vivo

The role of IL-2 in the immunological deficiency of lepromatous leprosy patients towards Mycobacterium leprae have been studied further. After initial stimulation with M. leprae + IL-2, lepromatous lymphocytes could be restimulated with M. leprae alone. The specificity of the responses obtained varied. Some patients gave a stronger response to BCG as compared to M. leprae, while in others a stronger response to M. leprae as compared to BCG was obtained. Studies of the composition of lymphocytes in dermal infiltrates subsequent to injection of killed M. leprae revealed that in both tuberculoid and lepromatous patients, early accumulation of cell staining for both IL-2 receptor and IL-2 were seen. However, with time IL-2 receptor and IL-2 staining lymphocytes diminished in lepromatous infiltrates, while these were maintained in tuberculoid lesions.

A microassay for quantitatively detecting the epstein-barr virus receptor on single cells utilizing flow cytometry

A quantitative microassay for detecting and analyzing the Epstein-Barr virus receptor (EBVR) utilizing fluorescein-conjugated virions is presented. The test is virus substrain-specific. Both the B95-8 and P3HR-1 strains were labelled and adsorbed to a variety of targets. Relative binding of virus was assessed by flow cytometry, the results being directly comparable with those obtained by earlier methods. Cell size and cellular DNA content were measured simultaneously with virus binding, thus enabling us to calculate EBVR density and to correlate receptor synthesis and cell cycle stage.

The Roles of the World Health Organization in Tropical Disease Research

The World Health Organization represents a unique focus of health for countries, particularly in the developing world, and its mission has been to emphasize the importance of primary health care throughout the world. Perhaps less appreciated is the fact that this effort has been supported in the past 10 years by a series of special programs designed to develop new tools and strategies, or “interventions,” ultimately to improve the primary health care effort. This requires new tools, new tools require new knowledge, and new knowledge requires research. To the question of how relevant research is likely to be to the practical goals of an international organization like WHO, let me remind you that it is precisely research that made it possible to discard the enormously expensive “iron lungs” used for poliomyelitis victims, and to develop effective and inexpensive vaccines to prevent the disease.