Borrelia burgdorferi activates a T helper type 1-like T cell subset in Lyme arthritis

Response of soluble IL-2 receptor, interleukin-2 and interleukin-6 in patients with positive and negative Borrelia burgdorferi serology

This study was designed to investigate serum soluble interleukin-2 receptor (S-IL-2R), interleukin-2 (IL-2) and interleukin-6 levels (IL-6) in patients with either a positive or negative Borrelia burgdorferi serology. Serum samples from 101 individuals, divided in to five groups according to clinical symptoms and outcome of serology were analysed. Samples of cerebrospinal fluid (CSF) from nine of the individuals were also studied. The highest average serum S-IL-2R levels (1,180 +/- 1,140 U/ml) were found in patients with erythema migrans, the hallmark of Lyme borreliosis, followed by patients with symptoms closely related to Borrelia infection (900 +/- 1,200 U/ml) and with a strong positive serology. In two patients with central nervous system (CNS) involvement, increased levels of S-IL-2R of 920 and 620 U/ml respectively (normal value < 50 U/ml) were detected in the CSF. No statistically significant relationship between IgG or IgM antibody activity and serum S-IL-2R levels was found. Detectable levels of IL-2 were only found in three patients. Increased levels of IL-6 were found in sera from 14 patients. The highest concentration, 90 pg/ml (normal value < 10 pg/ml), was measured in a patient presenting with vasculitis. In conclusion, B. burgdorferi infection causes a moderate increase of serum S-IL-2R levels, although there is no relationship between the severity of the infection, as estimated by the antibody concentration or to serum IL-2 or IL-6 levels. Secondary complications of the infection, such as vasculitis, may cause an increased level of serum IL-6.(ABSTRACT TRUNCATED AT 250 WORDS)

Divergent T-cell cytokine patterns in inflammatory arthritis

A major immunoregulatory mechanism in inflammatory infections and allergic diseases is the control of the balance of cytokines secreted by Th1/Th2 subsets of T helper (Th) cells. This might also be true in autoimmune diseases; a Th2 pattern that prevents an effective immune response in infections with intracellular bacteria may favor immunosuppression in autoimmune disease. The pattern of cytokine expression was compared in the synovial tissue from patients with a typical autoimmune disease, rheumatoid arthritis, and with a disorder with similar synovial pathology but driven by persisting exogenous antigen, reactive arthritis. We screened 12 rheumatoid and 9 reactive arthritis synovial tissues by PCR and in situ hybridization for their expression of T-cell cytokines. The cytokine pattern differs significantly between the two diseases; rheumatoid arthritis samples express a Th1-like pattern whereas in reactive arthritis interferon gamma expression is accompanied by that of interleukin 4. Studying the expression of cytokines by in situ hybridization confirmed the results found by PCR; they also show an extremely low frequency of cytokine-transcribing cells. In a double-staining experiment, it was demonstrated that interleukin 4 is made by CD4 cells. These experiments favor the possibility of therapeutic intervention in inflammatory rheumatic disease by means of inhibitory cytokines.

Role of TH1/TH2 cytokines in HIV infection

Different experimental approaches were used to prove or disprove the "TH1/TH2 switch theory" of HIV-infection. No increase, or even a decrease, in the production of TH2-type cytokines (IL-4, IL-5, and IL-10) by either bulk circulating mononuclear cells or CD4+ T-cell clones generated by PHA stimulation of single T cells from HIV-infected individuals in all stages of disease compared to HIV-negative donors was observed. However, enhanced proportions of CD4+ T-cell clones able to produce both TH1-type and TH2-type cytokines (TH0 clones) were derived from either skin-infiltrating, in vivo-activated, T cells or in vitro antigen-stimulated peripheral blood T cells of HIV-infected individuals. Of note, TH1, TH2 and TH0 clones obtained from HIV-seronegative healthy donors showed different ability to support viral replication after infection with HIV in vitro. All TH2 and most TH0 clones supported HIV replication efficiently, whereas TH1 clones did not. These results suggest preferential HIV replication in T cells producing TH2-type cytokines rather than TH1/TH2 switch in HIV infection.

Human T helper cells reactive with somatic bacterial antigens belong to the Th1 subset

The aim of this study was to characterize the cytokine secretion patterns of human T helper cells from healthy donors reactive with somatic antigens from various bacteria, the nematode Anisakis and tetanus toxoid. From the peripheral blood of four healthy donors we have established 70 T cell lines reactive with antigens from Yersinia, Salmonella, Morganella, Klebsiella, Serratia, Escherichia, Chlamydia, Shigella, Streptococcus, tetanus toxoid and Anisakis, respectively. Our results show that all T cells reactive with bacteria produce interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), but no interleukin (IL)-4 and no or very little IL-2 and IL-10 and, thus, belong to the Th1 subset, while T cells reactive with tetanus toxoid or Anisakis belong to the Th0 subset with production of IFN-gamma, IL-2, IL-4, IL-10 and TNF-alpha. In summary, our data further substantiate the concept of a functional diversity of human T helper cells with respect to their cytokine profiles. Furthermore, they indicate that a Th1 cytokine profile is not restricted to intracellular bacteria.

Role of cytokines in determining T-lymphocyte function

Early events in an immune response stimulate the production of cytokines that direct the subsequent development of T-helper (Th) subsets with discrete patterns of cytokine production. These events are dictated by the type of antigen/microorganism administered to a host, as well as dose and route of immunization. Bacterial stimuli activate macrophages of the innate immune response to produce IL-12 and drive Th1 development and cell-mediated immunity. Conversely, production of IL-4 early in an immune response favors a Th2 or allergic/humoral immune response. The ability of IL-4 and IL-10 to inhibit Th1 development and effector function, as well as the requirement of committed Th1 cells for co-stimulators to induce maximal IFN-gamma production, suggests that cell-mediated immunity is under strict control, probably to achieve immunity with minimum immunopathology.

Acetylcholine receptor-reactive T cells in myasthenia gravis: evidence for the involvement of different subpopulations of T helper cells

Patients with myasthenia gravis have a high prevalence of acetylcholine receptor-specific T lymphocytes in the peripheral blood. Our earlier study shows that these T lymphocytes are stimulated to secrete interferon (IFN)-gamma and interleukin (IL)-2 in response to the autoantigen. Such stimulated T cells may be subdivided into different subsets according to the pattern of cytokine production. In the present study we have investigated the subpopulations of cells by analyzing their IL-4, IFN-gamma and IL-2 secretion pattern. Autoantigen-stimulated IL-4 secretion was found in 55% of the patients, IFN-gamma secretion in 86% and IL-2 secretion in 72%. T lymphocytes from all patients who responded with increased IL-2 secretion also showed increased IFN-gamma secretion. Stimulated IL-4 secretion was detected both in the presence and absence of stimulated IFN-gamma secretion. Depletion of monocytes/macrophages from peripheral blood mononuclear cell preparation and treatment of the cells with a mouse anti-human HLA-DR antibody abolished the secretion of IFN-gamma and IL-4. There were positive correlations between the numbers of IFN-gamma- and IL-2-secreting T cells and the numbers of B cells secreting antibodies against the acetylcholine receptor. Our results show that acetylcholine receptor-stimulated T lymphocytes secrete IL-4, IFN-gamma and/or IL-2. This T cell response is major histocompatibility complex (MHC) class II-restricted and monocyte/macrophage-dependent. Our study indicates that both Th1/Th2 or Th0 subpopulations of the T lymphocytes are involved in the autoimmune response in myasthenia gravis.

TH1/TH2 subset analysis. I. Establishment of criteria for subset identification in PBMC samples from nonhuman primates

Cloned T-cell lines from two nonhuman primate species were phenotyped and their mRNA analyzed for cytokine profiles by RT-PCR procedures. PBMC from rhesus macaques showed a relatively high frequency of cloned T-cell lines with a TH1-like profile; PBMC from sooty mangabeys showed a relatively high frequency of TH2-like cloned T-cell lines. In vitro activated macaque PBMC also resulted in a high frequency of CD4+, CD8+ dual marked cells. These findings suggest that cytokine analysis of cloned T-cell lines from nonhuman primates provides a means to distinguish subsets of both CD4+ and CD8+ T cells.

T cells involved in psoriasis vulgaris belong to the Th1 subset

Although the pathogenesis of psoriasis vulgaris is still unknown, several characteristics point to an immunologically mediated process. Epidermal psoriatic lesions are characterized by a hyperproliferation of keratinocytes and an infiltration of T lymphocytes and granulocytes. Because the former may be mediated in part by lymphokines secreted by T cells, we have focused our interest on the in vivo and in vitro cytokine secretion patterns of T lymphocytes from psoriatic lesions. In five patients T lymphocytes were obtained from epidermal specimens. The cells were propagated with lectin and irradiated feeder cells and subsequently cloned by limiting dilution. The resulting T-cell clones were phenotypically and functionally characterized. Our data show that the majority of T-cell clones were CD4+ (74%), whereas only 25% were CD8+ and 1% were CD4-/CD8-. Also, we have further investigated the cytokine secretion pattern of T-cell lines or CD4+ T-cell clones, respectively. All cells tested produced interferon-gamma whereas only a minority secreted interleukin (IL)-4. Moreover, these cells produced high amounts of IL-2 but only little or no IL-10 or tumor necrosis factor-alpha. To correlate these data with the in vivo situation, biopsies from psoriatic lesions of five patients were investigated for the presence of the mRNA of IL-4, IL-10, and interferon-gamma using the polymerase chain reaction. In these biopsies only the mRNA for the Th1 cytokine interferon-gamma but not for the Th2 cytokines IL-4 and IL-10 could be detected. Identical experiments were performed to test the in vivo cytokine production of synovial fluid mononuclear cells of two patients with arthropathia psoriatica. Again, only the mRNA for interferon-gamma but not IL-4 could be detected. This indicates that T cells involved in psoriasis exhibit a Th1-like cytokine secretion profile.

Differential effects of IL-10 on proliferation and cytokine production of human gamma/delta and alpha/beta T cells

Gamma/delta TCR bearing T lymphocytes represent a T-cell subset whose functional relevance remains unclear. Nevertheless these T cells may play a role in the early immune response against bacteria. Until now the regulatory mechanisms on this response have not been investigated. The study described here evaluated the immunoregulatory effects of Interleukin-10 on gamma/delta and alpha/beta TCR-positive T-cell clones and freshly isolated peripheral-blood mononuclear cells (PBMC). IL-10 has been shown previously to inhibit lectin and antigen-induced proliferation and cytokine production by alpha/beta T cells. The results outlined below show that rhIL-10 strongly inhibits lectin-induced production of IFN-gamma, TNF-alpha, IL-2, and to a lesser degree proliferation and IL-4 production of both T-cell subsets. As IL-10 did not inhibit proliferation but at the same time strongly suppressed cytokine production in various experiments, the hypothesis that it could function as a growth factor for human T cells as has been described for murine thymocytes was tested. The data demonstrate that, although the gamma/delta T-cell clones tested do not produce IL-10 they can use it as a growth factor in combination with IL-2, IL-4 or alone. Furthermore, IL-10 has the same properties on human alpha/beta T-cell clones and PBMC. In summary, it is shown that IL-10 has pleiotropic effects on gamma/delta and alpha/beta TCR+ T cells by inhibiting lectin-induced cytokine production and by acting as a growth factor for these cells alone or in combination with IL-2 or IL-4.

Interleukin-1 favours the in vitro development of type 2 T helper (Th2) human T-cell clones

The effects exerted by interleukin-1 (IL1) on the growth and differentiation of human Th1 and Th2 cells were examined. Neither IL1 nor the IL1 receptor antagonist (IL1ra) had detectable activity toward the antigen- or anti-CD3 antibody-induced proliferative response of already established type 1 T helper (Th1) or type 2 T helper (Th2) clones. Moreover, neither exogenous IL1 addiction to, nor neutralization of, endogenously produced IL1 in bulk cultures before cloning changed the Th1-like cytokine profile of PPD-specific T-cell lines. Likewise, IL1 addition in bulk culture before cloning did not significantly affect the Th2-like cytokine profile of Der.p.I-specific T-cell lines (Dermatophagoides pteronyssinus group I). However, Der.p.I-specific T-cell lines, derived in the presence of anti-IL1 Ab, IL1ra or the M-20 IL1 inhibitor, exhibited the reduced ability to produce IL4 and an increased ability to produce interferon gamma (IFN gamma). More importantly, Der.p.I-specific T-cell lines derived in the presence of IL1ra developed into Der.p.I-specific CD4+ T-cell clones showing a Th0/Th1-like, instead of a Th0/Th2-like, cytokine profile. These data suggest that IL1 is not required for the growth of already established human Th1 or Th2 CD4+ T-cell clones and has no regulatory effects on the in vitro development of Th1-like cells, but it plays a critical role in the development of Th2-like cells.

Number of interleukin-4- and interferon-gamma-secreting human T cells reactive with tetanus toxoid and the mycobacterial antigen PPD or phytohemagglutinin: distinct response profiles depending on the type of antigen used for activation

The enzyme-linked immunospot (ELISPOT) assay has been proven to be an efficient and sensitive method for the enumeration of single cells secreting antibodies or cytokines. Here we have used this method to determine the number of interleukin-4 (IL-4)- and interferon-gamma (IFN-gamma)-producing cells in vitro secondary responses to tetanus toxoid (TT) and the mycobacterial antigen (purified protein derivative; PPD) or the mitogen phytohemagglutinin (PHA). PHA-induced IL-4 and IFN-gamma secretion was well correlated suggesting polyclonal activation of cells. This was not the case with the specific antigens, where PPD preferentially induced IFN-gamma- and very few IL-4-producing cells, while TT-induced both IL-4 and IFN-gamma. These differences are probably a reflection of the types of immunity the two antigens induce, mycobacteria preferentially inducing a cell-mediated T helper type 1 (Th 1) type of immunity, while immunity to tetanus is an antibody-dependent, Th 2 type of response. In individuals recently boosted with TT, a significant increase in both IL-4- and IFN-gamma-producing cells in response to TT was seen at day 7 after boost, followed by decline. This was in contrast to what was seen in response to PPD where an increase of IFN-gamma-producing cells after the TT boost at day 7 persisted for at least 14 days. These results suggest that after an in vivo boost both antigen-specific and nonspecific T cells are activated and that antigen-specific cells home to other organs and therefore may be difficult to demonstrate in the circulation. Our data show that the ELISPOT assay is a powerful tool for determining the frequency of cells secreting cytokines. The assay has several advantages over other assays since it is sensitive, measures the number of actually secreting cells, and avoids the problems of binding of cytokines to their cell-bound or soluble receptors.

Persistence of Borrelia burgdorferi in ligamentous tissue from a patient with chronic Lyme borreliosis

OBJECTIVE

To document the persistence of Borrelia burgdorferi in ligamentous tissue samples obtained from a woman with chronic Lyme borreliosis.

METHODS

Spirochetes were isolated from samples of ligamentous tissue, and the spirochetes were characterized antigenetically and by molecular biology techniques. The ligamentous tissue was examined by electron microscopy. Humoral and cellular immune responses were analyzed.

RESULTS

Choroiditis was the first recognized manifestation of Lyme disease in this patient. Despite antibiotic therapy, there was progression to a chronic stage, with multisystem manifestations. The initially significant immune system activation was followed by a loss of the specific humoral immune response and a decrease in the cellular immune response to B burgdorferi over the course of the disease. "Trigger finger" developed, and a portion of the flexor retinaculum obtained at surgery was cultured. Viable spirochetes were identified. Ultramorphologically, the spirochetes were situated between collagen fibers and along fibroblasts, some of which were deeply invaginated by these organisms. The cultured bacteria were identified as B burgdorferi by reactions with specific immune sera and monoclonal antibodies, and by polymerase chain reaction amplification and Southern blot hybridization techniques.

CONCLUSION

To our knowledge, this is the first report of the isolation of B burgdorferi from ligamentous tissue. This suggests that tendon tissues serve as a specific site of spirochete residence in human hosts.

Candida-specific Th1-type responsiveness in mice with experimental vaginal candidiasis

The role of systemic cell-mediated immunity (CMI) as a host defense mechanism in the vagina is poorly understood. Using a murine pseudoestrus model of experimental vaginal candidiasis, we previously found that animals given a vaginal inoculum of viable Candida albicans blastoconidia acquired a persistent vaginal infection and developed Candida-specific delayed-type hypersensitivity (DTH) responses. The present study was designed to characterize the peripheral CMI reactivity generated from the vaginal infection in mice and to determine whether pseudoestrus is a prerequisite for the induction of peripheral CMI reactivity. Mice treated or not treated with estrogen and given a vaginal inoculum of C. albicans blastoconidia were examined for 4 weeks for their vaginal Candida burden and peripheral CMI reactivity, including DTH responsiveness and in vitro Th1 (interleukin-2 [IL-2], gamma interferon [IFN-gamma]/Th2 (IL-4, IL-10)-type lymphokine production in response to Candida antigens. Results showed that although mice not treated with estrogen before being given a vaginal inoculum of C. albicans blastoconidia developed only a short-lived vaginal infection and harbored significantly fewer Candida CFU in the vagina compared with those given estrogen and then infected; DTH reactivity was equivalent in both groups. In vitro measurement of CMI reactivity further showed that lymph node cells from both estrogen- and non-estrogen-treated infected mice produced elevated levels of IL-2 and IFN-gamma in response to Candida antigens during the 4 weeks after vaginal inoculation. In contrast, lymph node cells from the same vaginally infected mice showed no IL-10 production and only small elevations of IL-4 during week 4 of infection. These results suggest that mice with experimental vaginal candidiasis develop predominantly Th1-type Candida-specific peripheral CMI reactivity and that similar patterns of Th1-type reactivity occur in mice regardless of the persistence of infection and the estrogen status of the infected mice.

Analysis of cytokine profiles in synovial T cell clones from chlamydial reactive arthritis patients: predominance of the Th1 subset

Subpopulations of human T cells (Th0, Th1 and Th2) can be distinguished by their cytokine-secretion pattern. Evidence is increasing from other studies that the outcome of a human disease may depend on the subpopulation of T cells that predominates at the site of inflammation. Reactive arthritis serves as a useful model of chronic inflammatory diseases, because the triggering antigen can be identified. Using this triggering antigen we raised 33 T cell clones reactive with Chlamydia trachomatis and 25 T cell clones that were not reactive, all from the synovial fluid of two patients suffering from Chlamydia-induced arthritis. Their cytokine secretion patterns for interferon-gamma (IFN-gamma), IL-2 and IL-4 were analysed, as also were mRNAs for IFN-gamma and IL-10 by in situ hybridization. Out of the 33 antigen-reactive clones 23 showed a Th1 pattern with IFN-gamma but not IL-4 secretion, while the remaining 10 exhibited a Th0 pattern. The clones that did not react with Chlamydia expressed all patterns of cytokine secretion, including a Th2 pattern, thus providing a control population that excludes bias in the sampling procedure. CD4 and CD8 clones displayed a similar cytokine-secretion pattern. In addition this study demonstrates for the first time the expression of IL-10 mRNA in T cell clones derived from synovial fluid, and this was not confined to the Th2 subset. The Th1 response that Chlamydia provoke can be regarded as appropriate for such an obligate intracellular pathogen.

Analysis of the in vitro cytokine production by liver-infiltrating T cells of patients with autoimmune hepatitis

The pathogenic mechanisms underlying the development of autoimmune hepatitis (AIH) are still unclear. Since AIH is associated with the presence of various autoantibodies and certain HLA subtypes, it is likely that T and B cells play a major role in this disease. In this study we have determined the functional capacities of in vivo preactivated liver-infiltrating T cells (LTC) from patients with AIH. As controls we used LTC from patients with non-autoimmune hepatitis (non-AIH). Our results show that preactivated LTC from patients with AIH predominantly (190/255 clones) reside in the CD4+ population, whereas LTC in non-AIH are dominated by the CD8+ phenotype (148/254 clones). In view of this finding we have investigated the cytokine secretion patterns of 102 randomly chosen CD4+ T cell clones from six patients with AIH. As controls we have used 58 CD4+ LTC from 11 patients with non-AIH. All clones were stimulated by lectin and irradiated accessory cells and subsequent cytokine production was evaluated. LTC from patients with AIH have a lower interferon-gamma (IFN-gamma)/IL-4 ratio compared with LTC from non-AIH. Although clones from some patients with AIH produced very high amounts of IL-4 in vitro, this was not a constant finding. These results show that in vivo preactivated LTC from patients with AIH are mostly CD4+ T cells that produce more IL-4 than IFN-gamma. In contrast, LTC from patients with non-AIH are dominated by CD8+ and CD4+ T cells that produce significantly less IL-4 than IFN-gamma. Thus, liver-infiltrating T cells from patients with AIH and non-AIH belong to different functional T cell subsets. This may have implications for the regulation of humoral and cellular immune responses in inflammatory liver disease.

Variables affecting the T cell receptor V beta repertoire heterogeneity of T cells infiltrating human renal allografts

Donor-specific, alloreactive T cell lines may be grown from cells infiltrating human renal allografts. These T cell lines utilize restricted T cell receptor (TCR) beta-chain variable (V beta) gene repertoires, although long-term culture appears to be necessary for restriction to be observed. This study was undertaken to determine the effects of potential selective pressures on the TCR repertoires of allograft-infiltrating cells. TCR V beta repertoires of 30 allograft-derived T cell populations, cultured for defined, short time periods, were examined using polymerase chain reaction. When first derived, V beta repertoires of graft-infiltrating T cells were as heterogeneous as those of peripheral blood lymphocytes (PBL). There was no relationship between the length of time an allograft was in situ or the extent of HLA mismatch and repertoire heterogeneity. Repertoire restriction was positively correlated with the length of time cells were cultured in vitro. Long-term, alloreactive mixed lymphocyte reactions (MLR), established from normal, unsensitized PBL, also demonstrated V beta repertoire restriction during expansion in vitro. Restricted alloreactive populations emerged much more slowly from the MLR than from the allograft-derived cultures, however, implying that graft infiltrates contain previously activated populations of T cells. This observation, taken together with the fact that long-term, graft-derived cell lines maintain donor specificity, suggests that functional subsets must be allowed to emerge from heterogeneous infiltrates before TCR repertoire may be correlated with alloreactivity and/or graft rejection.

Localized scleroderma associated with Borrelia burgdorferi infection. Clinical, histologic, and immunohistochemical observations

BACKGROUND

Recent reports have implicated Borrelia burgdorferi infection as a possible cause of localized scleroderma (LS).

OBJECTIVE

Our purpose was to describe the clinical, histologic, and immunopathologic features of patients with LS who had serum antibodies to B. burgdorferi.

METHODS

Ten patients were examined clinically and by routine microscopy. Biopsy specimens from seven patients were studied immunohistochemically with monoclonal antibodies. The proliferative response of peripheral blood mononuclear cells to B. burgdorferi was investigated in seven patients by lymphocyte proliferation assay.

RESULTS

Seven patients had plaque-type morphea, and three patients had linear scleroderma. Two patients had a history of previous erythema migrans. One patient had coexistent acrodermatitis chronica atrophicans, and in two patients lichen sclerosus et atrophicus was observed. Histologically, a prominent inflammatory phase with sclerosis of the connective tissue was shown in all patients. Immunohistochemical studies revealed that the inflammatory infiltrates consisted of both B and T lymphocytes, predominantly of the CD4+ subset. All 10 patients had strongly elevated serum antibodies to B. burgdorferi. Patients with LS showed significantly elevated lymphoproliferative responses to B. burgdorferi when compared with healthy control subjects.

CONCLUSION

Our findings suggest that some cases of LS are linked to Borrelia infection.

Rheumatoid inflammatory T-cell clones express mostly Th1 but also Th2 and mixed (Th0-like) cytokine patterns

This study was performed in order to characterize whether T cells from rheumatoid synovial inflammation belong to the Th1- or Th2-like functional subsets. Cytokine production was studied in 26 CD4+ alpha beta+ and 2 CD8+ alpha beta T-cell clones from the synovial fluid, the synovial membrane and peripheral blood of 5 patients. Fifteen of the CD4+ clones were raised against various mycobacterial antigens and 11 CD4+ clones and 2 CD8+ clones were raised unspecifically using PHA and/or IL-2. The specificities of these clones are not known. In the mycobacterial antigen-specific group, all CD4+ alpha beta T-cell clones produced IFN-gamma at high levels, while the production of IL-4 was generally absent or low (< 1 ng/ml), consistent with a Th1-like profile. Some of these clones, however, also produced various amounts of IL-10 which has been regarded as a Th2 product but can be produced also in lower amounts by Th1 cells. One HSP-65-specific clone produced levels of IL-4 and IL-10 in the same order as that of IFN-gamma, thus appearing to be Th0-like. Among the 11 unspecific CD4+ clones, 7 showed a Th1-like pattern but with lower levels of IFN-gamma than the antigen-specific clones. However, three clones did not produce any IFN-gamma activity but produced IL-4 and one of them also produced distinct amounts of IL-10, compatible with a Th2-like pattern. In addition, one of the clones also showed an almost equally strong IFN-gamma and IL-4 production, thus most likely representing a Th0-like clone.

OspA vaccination of mice with established Borrelia burgdorferi infection alters disease but not infection

C3H mice were actively immunized with outer surface protein A (OspA) at different intervals after infection with Borrelia burgdorferi to determine the effect of postexposure vaccination on the course of murine Lyme borreliosis. Mice were vaccinated with an OspA-glutathione transferase fusion protein or glutathione transferase (control) in complete Freund's adjuvant; vaccination was followed by two weekly booster injections in incomplete adjuvant. Two weeks after the final booster injection, organs were cultured for B. burgdorferi (blood, spleen, skin, and bladder) and examined for histopathology (joints and hearts). When vaccination was commenced in the early stages (5 to 14 days) of infection, active immunization with OspA partially cleared spirochetes from the bloodstream but did not eliminate them from other tissues or alter the course of joint or heart disease. Commencement of vaccination at 60 days after infection (at which time joint or heart disease is resolving), however, reduced both the number of mice and individual joints with arthritis, a result suggesting an acceleration of the resolution phase of the disease. Postexposure immunization with OspA may partially alter the course of murine Lyme arthritis but does not eliminate infection.

2nd European Symposium on Lyme Borreliosis. A NATO advanced research workshop. United Kingdom, 19-20 May 1993. Abstracts

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Long-term study of cell-mediated responses to Borrelia burgdorferi in the laboratory mouse

Borrelia burgdorferi infection of disease-susceptible (C3H) and -resistant (BALB) mice resulted in impaired proliferation to both T- and B-cell mitogens up to 30 days after inoculation. Interleukin-2 and -4 production was also impaired, paralleling the T-cell response to concanavalin A. Impaired lymphocyte proliferation could not be attributed to diminished numbers of T or B cells and was found to depend on the lymphoid organ (spleen or lymph node) examined. Prostaglandin production accounted for part of this immune dysfunction. Attempts to assess antigen-specific proliferation to B. burgdorferi were inconsistent, and delayed-type hypersensitivity responses were not detected. Adoptive transfer of T-enriched cells from chronically infected donors failed to prevent infection and disease development in recipient C3H mice. The current study emphasizes caution in the study of B. burgdorferi antigen-specific assays and argues against the role of a vigorous T-cell response in Lyme borreliosis in infected laboratory mice.

Specific and nonspecific responses of murine B cells to membrane blebs of Borrelia burgdorferi

Lymphocyte blastogenesis assays and immunoblotting were used to investigate and compare murine B-cell responses to preparations of extracellular membrane blebs (BAg) and spirochetes (Ag) of Borrelia burgdorferi. Immunoblotting BAg, Ag, and medium control preparations with serum from naive and infected C57BL/10 mice revealed that BAg and Ag had similar specific reactivity profiles except that major antigens of 83, 60, and 41 kDa were detected in Ag but not in BAg. It was determined that 1 microgram (dry weight) of Ag contained 0.0051 and 0.0063 microgram of outer surface proteins A (OspA) and OspB, respectively, whereas 1 microgram (dry weight) of BAg contained 0.0024 microgram of OspA and 0.0015 microgram of OspB. Both BAg and Ag caused blastogenesis in cultures of spleen cells from both groups of mice, but BAg-stimulated lymphocytes exhibited significantly greater (P < or = 0.05) blastogenesis after 2 or 6 days of culture than did lymphocytes stimulated by Ag or medium control. Flow cytometry and antibody capture enzyme-linked immunosorbent assays identified responding lymphocytes as B cells which secreted polyclonal immunoglobulin M (IgM) but not IgG or IgA. Treatment of BAg and lipopolysaccharide controls with polymyxin B resulted in as much as 20.7 and 54.3% mean decreases in blastogenesis, respectively. Fractionation of BAg or Ag by ultracentrifugation before culture with spleen cells from naive mice indicated that B-cell blastogenesis was probably associated with spirochetal membranes. The results of this study demonstrate that specific humoral responses are directed towards extracellular membrane blebs which lack the 83-, 60-, and 41-kDa antigens of intact spirochetes and that blebs also possess significant nonspecific mitogenic activity for murine B cells. This activity was not due entirely to typical lipopolysaccharide or OspA and OspB lipoproteins.

Interferon (IFN)-alpha, IFN-gamma, interleukin (IL)-2, and arachidonic acid metabolites modulate IL-4-induced IgE synthesis similarly in healthy persons and in atopic dermatitis patients

The role of cytokines and arachidonic acid metabolites in the regulation of IgE production in healthy persons and in atopic dermatitis patients with elevated IgE levels was studied. Interleukin-4 (IL-4) induced IgE production in peripheral blood mononuclear cells (PBMCs) of all donors, and no significant difference was found between the amounts of IgE produced by healthy persons and atopic dermatitis patients. Similarly, recombinant interferon (IFN)-alpha and IFN-gamma, as well as IL-2, inhibited IL-4-induced IgE production to a similar extent in both study groups. To evaluate the role of arachidonic acid (AA) metabolites in the regulation of IgE production, we added indomethacin, an inhibitor of the cyclooxygenase pathway, or nordihydroguaiaretic acid (NDGA), an inhibitor of the lipoxygenase pathway, to IL-4-treated cultures. Both indomethacin and NDGA strongly inhibited IL-4-induced IgE production. They also inhibited IL-4-induced IgG4 synthesis. No significant difference in the amount of inhibition was found between the two study groups. We were unable to restore the NDGA-induced inhibition of IgE-production by adding leukotrienes B4, C4, D4, or 5-HETE to the NDGA-treated cultures. PGE2 also failed to restore the indomethacin-mediated inhibitory effect. Consequently, NDGA- and indomethacin-mediated inhibitory effects do not appear to be mediated by any single factor studied. Collectively, our results show IFNs and IL-2 to be similar in effect in the modulation of IL-4-induced IgE synthesis in healthy and atopic persons.(ABSTRACT TRUNCATED AT 250 WORDS)

TH1 and TH2 cell antigen receptors in experimental leishmaniasis

The complexity and chronicity of parasitic infections have obscured the identification of biologically relevant antigens. Analysis of the T cell receptor repertoire used by mice infected with Leishmania major revealed the expansion of a restricted population of CD4+ cells. These cells expressed the V alpha 8-J alpha TA72, V beta 4 heterodimer in both progressive infection and protective immunity and across several major histocompatibility haplotypes. Thus, the same immunodominant parasite epitope drives the disparate outcomes of this infectious process, suggesting that candidate vaccine antigens selected by screening of immune individuals may be capable of exacerbating disease in genetically susceptible individuals.

Acrodermatitis chronic atrophicans: a chronic T-cell-mediated immune reaction against Borrelia burgdorferi? Clinical, histologic, and immunohistochemical study of five cases

BACKGROUND

Acrodermatitis chronica atrophicans (ACA) is a late manifestation of infection caused by Borrelia burgdorferi.

OBJECTIVE

Our purpose was to study the clinical, histopathologic, and immunohistochemical findings in patients with ACA to understand better the pathogenesis of the disease.

METHODS

Five patients were studied. Skin biopsy specimens were obtained from active lesions for histologic and immunohistochemical studies.

RESULTS

Clinical lesions included an initial erythematous discoloration in one patient and violaceous infiltrated plaques and nodules in four patients, three of whom also had late atrophic lesions. Biopsy specimens showed a dermal perivascular and interstitial lymphocytic infiltrate with plasma cells. There was a predominance of CD3+, CD4+ T cells in the dermal infiltrate. B cells were present in three patients. The dermal infiltrate showed an intense expression of lymphocyte function-associated antigen. The intercellular adhesion molecule type 1 was expressed on endothelial cells, perivascular mononuclear cells, and focally on basal keratinocytes.

CONCLUSION

Our findings suggest that a chronic, T-cell-mediated immune reaction against B. burgdorferi is involved in the pathogenesis of ACA.

Leishmania donovani-reactive Th1- and Th2-like T-cell clones from individuals who have recovered from visceral leishmaniasis

Infections in humans by Leishmania donovani parasites can result in a fatal disease, visceral leishmaniasis (VL), or in a self-limiting asymptomatic infection. In murine models of the infection employing Leishmania major, the course of the disease can be directed into a VL-like syndrome by interleukin-4 (IL-4)-producing Th2 cells, or cure may result by Th1 cells secreting gamma interferon (IFN-gamma). The present study examined the potential of human T cells to generate Th1 or Th2 responses to L. donovani. The profiles of IFN-gamma, IL-4, and lymphotoxin secretion after antigen stimulation were analyzed in a panel of L. donovani-reactive CD4+ human T-cell clones generated from individuals who had recovered from VL after antimonial treatment. Two of the T-cell clones produced large amounts of IL-4 without production of IFN-gamma, seven clones produced both IFN-gamma and IL-4, and eight produced only IFN-gamma. This is the first report of a Th1- and Th2-type response in human leishmaniasis. These results suggest that in analogy with murine models, there is a dichotomy in the human T-cell response to L. donovani infections. Preferential activation of IL-4-producing Th2-like cells may be involved in the exacerbation of human VL, whereas activation of IFN-gamma-producing Th1 cells may protect the host from severe disease. Identification of leishmanial antigens activating one or the other type of T cells will be important in the development of vaccines against leishmaniasis.

Human peripheral blood basophils primed by interleukin 3 (IL-3) produce IL-4 in response to immunoglobulin E receptor stimulation

In contrast to most cytokines, interleukin 4 (IL-4) expression is restricted to T lymphocytes, with the exception of mast cell lines and mast cells, as more recently demonstrated in rodents. Little is known, however, about the capacity of human nonlymphoid cells to produce IL-4. In this study we show that mature human basophils are capable of expressing IL-4 and examine the regulation of IL-4 production in comparison with the lipid mediator leukotriene C4. IL-4 was produced upon immunoglobulin E receptor (IgER) activation of basophils cultured with IL-3, a cytokine previously shown to prime these cells for enhanced release of inflammatory mediators. In some experiments, IL-3 or IgER activation alone also induced IL-4 production close to the detection limit. The effect of IL-3 on IgER-dependent IL-4 expression was dose and time dependent: maximal IL-4 production occurred between 18 and 48 h preexposure of basophils to 3-10 ng/ml IL-3. IgER-induced IL-4 synthesis and release by basophils cultured with IL-3 was rapid and complete after 6 h. In contrast to IL-3, other cytokines (IL-5, granulocyte/macrophage colony-stimulating factor, and nerve growth factor) that also prime basophils for enhanced histamine and leukotriene C4 release did not promote IgER-induced IL-4 synthesis. Basophils appear to secrete a "TH2-like" cytokine profile since no detectable IL-2 or interferon gamma was produced upon IgER activation. Mononuclear cells (depleted of basophils), cultured in parallel, did not release IL-4 in response to IL-3 and/or IgER activation, and produced approximately ten times less IL-4 than basophils upon nonspecific activation by phorbol ester and calcium ionophore. Thus, human basophils are an important cellular source of IL-4, and may, therefore, in addition to their inflammatory effector functions, also regulate the differentiation of T helper cells and B cells, in particular in allergic diseases.

A TH1-->TH2 switch is a critical step in the etiology of HIV infection

This viewpoint proposes that an imbalance in the TH1-type and TH2-type responses contributes to the immune dysregulation associated with HIV infection, and that resistance to HIV infection and/or progression to AIDS is dependent on a TH1-->TH2 dominance. This hypothesis is based on the authors' findings that: (1) progression to AIDS is characterized by loss of IL-2- and IFN-gamma production concomitant with increases in IL-4 and IL-10; and (2) many seronegative, HIV-exposed individuals generate strong TH1-type responses to HIV antigens.

Pharmacologic modulation of Th1- and Th2-associated lymphokine production

Murine helper T cells can be divided into at least two groups, Th1 and Th2, based on the patterns of lymphokine secretion after antigenic or mitogenic stimulation. Recently, a similar subdivision was proposed in the human situation. Interestingly, the different patterns of lymphokine production correlate with different effector functions of the Th subpopulations. Th1 cells appear to dominate delayed type hypersensitivity reactions. Conversely, Th2 cells dominate the immune response to allergens and probably play an important role in allergic disorders. One of the clinical manifestations in which Th2 cells appear to dominate the immune response is allergic asthma. The mainstay of therapy in asthmatic persons is formed by glucocorticoid and beta-adrenoceptor agonist treatment. A differential pharmacological modulation of the lymphokine production by Th1 and Th2 cells can be of therapeutic relevance in allergic diseases in which an inappropriate balance between Th1 and Th2 cells exists. Such a differential modulation may underlie the beneficial usage of glucocorticoids and beta-adrenoceptor agonists in the treatment of asthma. The present report summarizes the effects of glucocorticoids and cAMP modulating agents on the activation and lymphokine production of T lymphocytes and Th subsets. Additionally, the effect of other steroid hormones is evaluated.

Development of human Th1 and Th2 cytokine responses: the cytokine production profile of T cells is dictated by the primary in vitro stimulus

Regulation of interleukin (IL)-4 production, but not IL-2 production, was found to be quite different in either freshly isolated T cells or T cell clones. Both fresh T cells and T helper 2-like clones produced IL-4 when stimulated with anti-CD2 in combination with anti-CD28. However, whereas T cell clones showed enhanced IL-4 production when phorbol 12-myristate 13-acetate (PMA) was used in addition to anti-CD2 and anti-CD28, IL-4 production by fresh T cells was inhibited by the presence of PMA. Prestimulation of fresh T cells led to the following observations: (a) activation in the absence of PMA led to a reversal of the PMA effect and (b) within 2 days these cells resembled T cell clones in that IL-4 production was no longer inhibited by PMA. When prestimulation was carried out in the presence of PMA, the inhibition of IL-4 production seemed irreversible. Removal of PMA after 3 days did not lead to renewed capability of IL-4 production, whereas IL-2 production was unimpaired. Our data show that the capacity of cultured T cells to produce IL-4 is determined and fixed during the first 2-3 days of stimulation.

Predominance of Th1-type T cells in synovial fluid of patients with Yersinia-induced reactive arthritis

The pathogenetic mechanisms underlying the development of reactive arthritis and the functional capacities of synovial T cells specific for Yersinia enterocolitica are still unclear. In this study we have determined the cytokine secretion patterns of 24 CD4+ synovial fluid (SF)-derived T cell clones from 2 patients with Yersinia-induced reactive arthritis, 16 clones specific for different Yersinia antigens and 8 clones as controls. The clones specific for Yersinia antigens predominantly belong to the T helper cell 1 (Th1) subset with production of interferon (IFN)-gamma and interleukin (IL)-2, but no IL-4, whereas SF T cells not reactive with Yersinia antigens produce IL-2, IL-4 and IFN-gamma and thus belonged to the Th0 subset. Moreover, short-term T cell lines established from SF and peripheral blood showed the same pattern. To further analyze the functional relevance of these data we investigated the influence of IFN-gamma and IL-4 on the intracellular killing of Yersinia in a human glioblastoma cell line. Our data show that the Th1 cytokine IFN-gamma promotes intracellular killing of Yersinia, whereas this effect is antagonized by the Th2 cytokine IL-4. Furthermore, the Th2 cytokine IL-10 inhibited the antigen-specific proliferative response and IFN-gamma and IL-2 production by the Th1 cells. These results provide insight into the antibacterial mechanisms at work in reactive arthritis after infection with Yersinia enterocolitica and, for the first time, reveal the cross-regulatory properties of cytokines derived from Th1 and Th2 cells in a human immune response to bacterial antigens.

Induction of TH1 and TH2 responses: a key role for the 'natural' immune response?

What pushes a T-cell response towards a predominantly TH1 or TH2 phenotype? Several factors have been proposed, including the properties of antigens, dose of antigen, site of exposure and ongoing immune response in the host. Here, Sergio Romagnani presents new evidence to indicate a determining role for the 'natural' immune response, including NK cells and cells of the mast cell/basophil lineage, in the subsequent 'specific' T-cell response.

Borrelia burgdorferi HSP70 homolog: characterization of an immunoreactive stress protein

The gene encoding an immunoreactive Borrelia burgdorferi HSP70 homolog was isolated and characterized. The predicted amino acid sequence of this spirochetal protein confirms that this gene encodes a member of the HSP70 family of proteins. Although there appears to be a single copy of this gene on the spirochetal chromosome, two distinct transcripts hybridizing to the hsp70 probe are detected in RNA isolated from B. burgdorferi. The amount of spirochetal HSP70 RNA transcripts is shown to be thermally regulated. Antibodies in the serum of three Lyme arthritis patients and cloned T-cell lines isolated from one patient with Lyme arthritis recognize the expressed recombinant HSP70, indicating that it is an immunologically important spirochetal antigen. Antibodies in a rabbit antiserum, as well as antibodies in the serum of two of three Lyme arthritis patients examined, bound to expressed truncated recombinant HSP70s with 250 amino acids deleted from either the amino or carboxy terminus of the protein. However, antibodies in the serum of three Lyme arthritis patients, which were reactive with spirochetal HSP70, did not cross-react with human HSP70 proteins.

Evidence for B-lymphocyte mitogen activity in Borrelia burgdorferi-infected mice

Borrelia burgdorferi produces a mitogen for murine B lymphocytes which can be measured in vitro by polyclonal stimulation of proliferation and immunoglobulin production (R. Schoenfeld, B. Araneo, Y. Ma, L. Yang, and J. J. Weis, Infect. Immun. 60:455-464, 1992). Sonicated B. burgdorferi cells also stimulated IL-6 production by splenocyte cultures. We have used the murine model for Lyme disease described by Barthold et al. (S. W. Barthold, D. S. Beck, G. M. Hansen, G. A. Terwilliger, and K. D. Moody, J. Infect. Dis. 162:133-138, 1990) to determine whether the B. burgdorferi B-cell mitogen is expressed during active infection. To correlate arthritic changes with immune events, we have studied two strains of mice injected with B. burgdorferi; one of them, C3H/HeJ, developed severe disease, and the other, BALB/c, developed only mild disease. C3H/HeJ mice displayed a persistent 10-fold increase in circulating immunoglobulin G (IgG) levels, a 2-fold increase in IgM levels, and a 15-fold increase in peripheral lymph node B-cell numbers, providing evidence of mitogenic activity. Infected BALB/c mice also had evidence for mitogen activity, since the IgG level in serum increased three- to fourfold. The bulk of the increase in circulating IgG levels was not directed against B. burgdorferi antigens, supporting the occurrence of polyclonal B-cell activation. Analysis of IgG isotypes pointed out a contrast between C3H/HeJ and BALB/c mice in that levels of all isotypes were elevated somewhat in both strains of infected mice but IgG2a levels were much more dramatically increased in the C3H/HeJ mice (28-fold) than in the BALB/c mice (4-fold). In this study, interleukin-6 levels were found to be persistently elevated in the serum of infected C3H/HeJ mice. Interestingly, interleukin-6 levels in serum were much lower in the infected BALB/c mice. These findings indicate that the B. burgdorferi mitogen is active in infected animals and may contribute to the inflammatory and immune response to infection.

Aberrant interleukin (IL)-4 and IL-5 production in vitro by CD4+ helper T cells from atopic subjects

The cytokine secretion profiles of T cell lines (TCL) specific for purified protein derivative (PPD) or streptokinase (SK), contemporarily derived from nine atopic and nine nonatopic individuals, were compared. Upon stimulation with phorbol myristate acetate (PMA) plus anti-CD3 monoclonal antibody (mAb), all TCL from both atopics and nonatopics produced interleukin (IL)-2 and interferon (IFN)-gamma. The mean IL-2 production by PPD- or SK-specific TCL from both atopics and nonatopics was similar, whereas the mean IFN-gamma production by TCL derived from atopics was significantly lower. In addition, both PPD- and SK-specific TCL from atopics produced detectable amounts of IL-4 and IL-5, whereas the corresponding TCL derived from nonatopics did not. A total number of 107 and 99 PPD-specific CD4+ T cell clones (TCC) were then derived from TCL of 4 atopic and 4 nonatopic donors and assessed for their profile of cytokine production in response to stimulation with either PMA plus anti-CD3 mAb or the specific antigen. Under both these experimental conditions, virtually all PPD-specific TCC from both atopic and nonatopic individuals produced IL-2 and IFN-gamma. In contrast, the great majority of PPD-specific TCC derived from nonatopic individuals did not produce IL-4 and IL-5, whereas high proportions of PPD-specific TCC derived from atopic donors displayed the ability to produce noticeable amounts of IL-4 and IL-5 besides IL-2 and IFN-gamma. These data indicate that CD4+ T cells from atopic individuals are able to produce IL-4 and IL-5 in response to bacterial antigens, such as PPD and SK, that usually evoke responses with a restricted type-1 T helper (Th1)-like cytokine profile in nonatopic individuals. Aberrant IL-4 production by Th cells may represent one of the immune alterations responsible for enhanced IgE antibody production in atopic people.

T Cells Cloned from Human Rheumatoid Synovial Membrane Functionally Represent the Th 1 Subset

The presence of activated T cells in the synovial membrane of patients with rheumatoid arthritis (RA) suggests a role for these cells in the pathogenesis of the disease. Recent evidence indicates that human T cells may fall into functional categories dependent on their cytokine profile and cytotoxic capacity. The human Th1 subset is cytolytic and produces high levels of IFN-gamma whereas the Th2 type of T cell produces IL-4. In order to investigate whether Th1 or Th2 type cells are present in the inflammatory synovial membrane in RA, a panel of synovial membrane derived T-cell clones (n = 19) was generated and studied functionally. Anti-CD3-induced cytotoxicity assays were performed to demonstrate the cytotoxic potential of clones. Except for two, all clones were cytolytic in this test. Clone cells were activated to initiate cytokine production and assessment of the cytokine levels showed that all clones produced large amounts of IFN-gamma (18 out of 19 clones: over 50,000 pg/ml) whereas IL-4 was absent or present in minimal amounts (17 out of 19 clones: less than 1000 pg/ml). The production of IL-1, IL-2 and IL-6 was variable. The functional characteristics of the clones studied indicate that they may resemble the Th1 subtype of T cells. Our data suggest a relation between Th1-type functions the chronic inflammation characteristic of RA.

The CD27- subset of peripheral blood memory CD4+ lymphocytes contains functionally differentiated T lymphocytes that develop by persistent antigenic stimulation in vivo

On the basis of expression of the T cell differentiation antigen CD27, human peripheral blood CD4+ memory cells can be divided into two subsets, a large CD45RA-CD27+ (82%) and a small CD45RA-CD27- (18%) population. Analysis of the functional properties of these memory T cell subsets showed that proliferative responses to the recall antigen tetanus toxoid (TT), shortly after booster immunization, were mainly confined to the CD27- population. Also, in atopic individuals, proliferative responses to allergens for which these individuals are sensitized, were limited to the CD45RA-CD27- population. After stimulation with CD3 monoclonal antibody and phorbol ester, CD27+ cells produced vast amounts of interleukin (IL)-2 but minimal amounts of IL-4, whereas in marked contrast, CD27- T cells secreted low levels of IL-2 and high levels of IL-4. The capacity of the vast majority of these latter cells to produce IL-4 was found to be a stable feature since high IL-4 secreting T cell clones were generated from the CD27- subset. These findings suggest that upon renewed as well as chronic antigenic stimulation in vivo, memory T cells acquire the CD45RA-CD27- phenotype and that, as a consequence, in this subset functionally differentiated CD4+ T cells are compartmentalized. Our results predict that analysis of the small CD27- subset of memory cells, that makes up approximately 10% of the peripheral blood T cell population, will provide information on the specificity and function of responding CD4+ T cells at a given point in time in healthy and diseased individuals.

The polymerase chain reaction for detection of T-cell antigen receptor expression

Applications of the polymerase chain reaction have revolutionized the field of immunogenetics, particularly in studies of human leukocyte antigen class II polymorphism, and more recently in the analysis of T-cell receptor usage. However, the enormous diversity and variability of the T-cell receptor complex have made the amplification of the complete repertoire difficult. Several methods have been devised to address this problem. Each system is described with recent examples of its use and an assessment of its advantages and disadvantages. The use of quantitative polymerase chain reaction in T-cell receptor analysis is also discussed. The elucidation of the T-cell repertoire involved in a pathogenic process can have therapeutic implications, given the success of reversing experimental autoimmune disorders by directing specific forms of immunotherapy against V region gene products.