[Secondary hypogammaglobulinemia with recurrent opportunistic pulmonary infection]. / Wiederholte opportunistische Infektionbei sekundärem Immunglobulinmangel.

Secondary hypogammaglobulinemia may be a relevant predisposing condition in patients with recurrent bacterial upper airway disease (pneumonia, sinusitis) or first-time opportunistic infection, particularly if additional immunosuppressive factors like underlying hematological disease or immunosuppressive therapy are present. As an example, we present a retired farmer with myeloma, treated Hodgkin-lymphoma and hypogammaglobulinemia suffering from the third episode of Rhodococcus equi pneumonia. Screening for hypogammaglobulinemia is recommended in patients with unexplained recurrent bacterial airway infection or first time opportunistic disease, particularly with micro-organisms controlled by humoral immunity. Screening should include the analysis of total immunoglobulin levels (IgA, IgG and IgM). If results are ambiguous, tetanus toxoid and pneumococcal polysaccharide vaccine should be administered with measurement of specific antibody titer before and one month after vaccination. An adequate antibody response largely excludes a clinically significant humoral immunodeficiency. If hypogammaglobulinemia is present in a patient with recurrent or opportunistic infections, periodical substitution of IVIG in a dose and frequency to prevent further infectious episodes should be initiated. This is usually achieved with an IVIG-dose of 0.4g/kg body weight every 3 - 4 weeks to reach a trough IgG-level of 5 - 7g/L.

Quantitative determination of IgM antibodies reduces the pitfalls in the serodiagnosis of tick-borne encephalitis.

BACKGROUND: Tick-borne encephalitis (TBE) is the most important arbovirus disease in parts of Europe and Asia. Its laboratory diagnosis depends on the detection of specific IgM antibodies which can be impeded by (1) long-time persistence of IgM antibodies after infection, (2) vaccine-induced IgM antibodies, and (3) cross-reactive IgM antibodies from other flavivirus infections. OBJECTIVES: To assess the extent of interference factors in the serodiagnosis of TBE that might lead to the false positive assignment of a recent infection. STUDY DESIGN: We quantified TBE virus-specific IgM and IgG antibodies in sera collected at different time points from cohorts of (1) 61 TBE patients, (2) 131 TBE vaccinees, and (3) 42 patients with recent dengue or West Nile virus infections. RESULTS: All of the TBE patients were IgM- and IgG-positive upon hospitalization and 87% of acute TBE sera had IgM antibody titers of >500 Arbitrary Units (AU). These titers rapidly declined and only 16% of TBE patients had low IgM titers ≥9 months after infection. Vaccine-induced as well as flavivirus cross-reactive IgM antibodies were rarely detectable and of low titer. CONCLUSIONS: Most of the potential problems of TBE serodiagnosis can be resolved by the quantification of IgM antibodies in a single serum sample taken upon hospitalization. High IgM values (>500 AU in our assay) are indicative of a recent infection. Lower IgM values, however, may require the analysis of a follow-up sample and/or a specific neutralization assay to exclude the possibilities of IgM persistence, vaccine-induced IgM antibodies or heterologous flavivirus infections.

[Brucellosis as a differential diagnosis of cancer of the testes]. / Die Brucellose als Differentialdiagnose zum Hodentumor.

Brucellosis has become a rarity in industrialized countries. The manifestation as a granulomatous inflammation of the testes is described with an incidence of 5-40% in the literature and therefore is a relatively common complication of brucellosis. In cases of pain of the testes combined with B symptoms, a systemic inflammation with a local complication should also be considered besides cancer of the testes.

Disseminated toxoplasmosis in a patient with non-Hodgkin lymphoma.

Toxoplasmosis is a well-recognized opportunistic disease in HIV-infected individuals that is caused by the reactivation of a previous infection, primarily in the central nervous system, during profound immunodeficiency. Toxoplasmosis has been described more rarely in patients with cancer and chemotherapy. We report a case of a patient with a history of chemotherapy for non-Hodgkin lymphoma who developed pain and progressive paresthesia of the right arm 6 weeks after remission. Relapsing lymphoma was suspected, and steroid and radiation treatment were initiated, but the patient died 5 days later due to multiple organ failure. Autopsy revealed disseminated toxoplasmosis. This case illustrates that toxoplasmosis should be suspected in patients with neoplastic disease, especially lymphomas, who present with unexplained neurologic, pulmonary, or febrile symptoms during or after chemotherapy.

[Primary HIV-1 infection in Zurich: 2002-2004]. / Die akute HIV-1-Infektion in Zürich: 2002-2004.

Acute HIV-infection mostly presents with unspecifc symptoms. Thus the acute retroviral syndrome is often not readily recognized. Here we present an interim analysis of a prospective study from 62 patients with documented acute HIV infection acquired between January 2002-August 2004 in the greater Zurich area. 61.5% of patients were infected by homosexual contacts, mostly with HIV-1 subtype B, 34% acquired infection by heterosexual contacts, often with non-B-virus subtypes. Transmission occurred in all sexually active age groups (18-72 years). Clinical symptoms presented as follows: fever (77%), pharyngitis (56%), fatigue (52%), gastrointestinal symptoms (45%), rash (39%). On first physician contact, an ARS was only suspected in 27% of the cases. Patients primarily called on their family doctors (37.5%), went to see larger walk in clinics or emergency rooms (37.5%), and 16% were hospitalised. In 16% of patients other sexually transmitted diseases were diagnosed contemporaneously. Drug resistant virus (single class resistance) was transmitted in only one patient.

Viral escape mechanisms--escapology taught by viruses.

Viruses have 'studied' immunology over millions of years of coevolution with their hosts. During this ongoing education they have developed countless mechanisms to escape from the host's immune system. To illustrate the most common strategies of viral immune escape we have focused on two murine models of persistent infection, lymphocytic choriomeningitis virus (LCMV) and murine cytomegalovirus (MCMV). LCMV is a fast replicating small RNA virus with a genome prone to mutations. Therefore, LCMV escapes from the immune system mainly by two strategies: 'speed' and 'shape change'. At the opposite extreme, MCMV is a large, complex DNA virus with a more rigid genome and thus the strategies used by LCMV are no option. However, MCMV has the coding capacity for additional genes which interfere specifically with the immune response of the host. These escape strategies have been described as 'camouflage' and 'sabotage'. Using these simple concepts we describe the spectrum of viral escapology, giving credit not only to the researchers who uncovered this fascinating area of immunology but also to the viruses themselves, who still have a few lessons to teach.

Roles of tumour localization, second signals and cross priming in cytotoxic T-cell induction.

The vertebrate immune system has evolved to protect against infections that threaten survival before reproduction. Clinically manifest tumours mostly arise after the reproductive years and somatic mutations allow even otherwise antigenic tumours to evade the attention of the immune system. Moreover, the lack of immunological co-stimulatory molecules on solid tumours could result in T-cell tolerance; that is, the failure of T cells to respond. However, this may not generally apply. Here we report several important findings regarding the immune response to tumours, on the basis of studies of several tumour types. First, tumour-specific induction of protective cytotoxic T cells (CTLs) depends on sufficient tumour cells reaching secondary lymphatic organs early and for a long enough duration. Second, diffusely invading systemic tumours delete CTLs. Third, tumours that stay strictly outside secondary lymphatic organs, or that are within these organs but separated from T cells by barriers, are ignored by T cells but do not delete them. Fourth, co-stimulatory molecules on tumour cells do not influence CTL priming but enhance primed CTL responses in peripheral solid tumours. Last, cross priming of CTLs by tumour antigens, mediated by major histocompatibility complex (MHC) class I molecules of antigen-presenting host cells, is inefficient and not protective. These rules of T-cell induction and maintenance not only change previous views but also rationales for anti-tumour immunotherapy.

Immunodeficiency of alymphoplasia mice (aly/aly) in vivo: structural defect of secondary lymphoid organs and functional B cell defect.

Alymphoplasia mice (aly/aly) have been shown to be deficient for a nuclear factor-kappaB-inducing kinase involved in signal transduction of lymphotoxin beta receptor (LT-betaR) and of CD40, resulting in structural defects of secondary lymphoid organs and highly increased susceptibility to viral infections. We analyzed the anti-viral immune response of bone marrow chimeras (BMC) between aly/aly mice and (C57BL/6 x DBA2)F1 mice (B6D2F1) to evaluate in vivo whether the structural defects of secondary lymphoid organs or intrinsic B or T cell defects led to immunodeficiency in aly/aly mice. Transfer of aly/aly bone marrow into B6D2F1 mice (aly/aly-->B6D2F1) led to excellent T but poor B cell reconstitution of recipients. Antiviral cytotoxic T cell (CTL) responses of aly/aly-->B6D2F1 BMC were clearly improved compared to aly/aly mice whereas virus-neutralizing IgG reponses were virtually absent. Therefore, the inefficient CTL response was predominantly caused by the structural defect of secondary lymphoid organs and not by an intrinsic T cell defect. In contrast, B cells of aly/aly origin were unable to undergo isotype switch after viral infections, indicating an intrinsic B cell defect in vivo. Overall, aly/aly mice show the combined immunodeficient phenotype of mice deficient for LT-3R with B cells functionally deficient for CD40.

Antiviral B cell memory in the absence of mature follicular dendritic cell networks and classical germinal centers in TNFR1-/- mice.

TNFR1-/- mice have been shown to lack networks of mature follicular dendritic cells (FDCs) and they do not form germinal centers. With nonreplicating Ags, IgG titers were inefficiently induced and not maintained. In this study, the neutralizing Ab response and the establishment of B cell memory in TNFR1-/- mice after infection with vesicular stomatitis virus (VSV) were analyzed histologically and functionally. Immunization with VSV-derived protein Ags without adjuvant induced only IgM but no IgG Abs in TNFR1-/- mice, whereas VSV glycoprotein emulsified in CFA or IFA induced IgM and IgG responses that were short-lived and of moderate titer. However, infection with live VSV induced excellent neutralizing IgM and IgG responses in TNFR1-/- mice, and adoptively transferable B cell memory was generated and persisted for more than 300 days. In contrast, IgG levels and Ab-forming cells in the bone marrow declined within 300 days by 90-95% compared with controls. These findings suggest that 1) increased Ag dose and time of Ag availability can substitute for FDC-stored Ab-complexed Ag in the induction of efficient IgG responses in TNFR1-/- mice devoid of classical germinal centers; 2) the induction and maintenance of adoptively transferable B cell memory can occur in the absence of Ag bound to mature FDCs; and 3) the long-term maintenance of elevated IgG titers is largely dependent on FDC-associated persisting Ag. However, about 5-10% of the Ab production remained in the absence of detectable persisting Ag in TNFR1-/- mice, probably either due to immature FDCs being partially functional and/or due to long-lived plasma cells.

A comparison of T cell memory against the same antigen induced by virus versus intracellular bacteria.

Cytotoxic T cell (CTL) memory was analyzed after infection with lymphocytic choriomeningitis virus (LCMV) and recombinant Listeria monocytogenes (rLM) expressing the complete nucleoprotein of LCMV (rLM-NP(actA)) or only the immunodominant epitope of H-2(d) mice (rLM-NP(118-126)). Immunization with LCMV and rLM induced a long-lived increased CTL precursor (CTLp) frequency specific for the viral (NP(118-126)) and for the bacterial (LLO(91-99)) epitope, respectively. However, after infection with rLM memory, CTLs were less protective against an intravenous LCMV challenge infection than a comparable number of LCMV-induced memory T cells. LCMV, but not recombinant Listeria-induced memory T cells were able to protect against lethal choriomeningitis by LCMV or a subsequent peripheral infection with recombinant vaccinia virus expressing LCMV-NP. The protective memory after viral and after rLM immunization was paralleled by evidence of LCMV but not rLM antigen persistence on day 15 and 30 after vaccination. These results document a striking difference in protective T cell memory between viral and bacterial vaccines and indicate that rapid T cell-dependent immune protection correlates with antigen persistence.

Immune surveillance against a solid tumor fails because of immunological ignorance.

Many peripheral solid tumors such as sarcomas and carcinomas express tumor-specific antigens that can serve as targets for immune effector T cells. Nevertheless, overall immune surveillance against such tumors seems relatively inefficient. We studied immune surveillance against a s.c. sarcoma expressing a characterized viral tumor antigen. Surprisingly, the tumor cells were capable of inducing a protective cytotoxic T cell response if transferred as a single-cell suspension. However, if they were transplanted as small tumor pieces, tumors readily grew. Tumor growth correlated strictly with (i) failure of tumor cells to reach the draining lymph nodes and (ii) absence of primed cytotoxic T cells. Cytotoxic T cells were not tolerant or deleted because a tumor antigen-specific cytotoxic T cell response was readily induced in lymphoid tissue by immunization with virus or with tumor cells even in the presence of large tumors. Established tumors were rejected by vaccine-induced effector T cells if effector T cells were maintained by prolonged or repetitive vaccination, but not by single-dose vaccination. Thus, in addition to several other tumor-promoting parameters, some antigenic peripheral sarcomas-and probably carcinomas-may grow not because they anergize or tolerize tumor-specific T cells, but because such tumors are immunologically dealt with as if they were in a so-called immunologically privileged site and are ignored for too long.

IL-12 is not required for induction of type 1 cytokine responses in viral infections.

To investigate the physiological role of IL-12 in viral infections in terms of T cell cytokine responses involved in virus-specific Ig isotype induction and in antiviral protection, immune responses elicited upon infection of IL-12-deficient mice with lymphocytic choriomeningitis virus (LCMV) or vesicular stomatitis virus (VSV) were studied. Infection of IL-12-deficient mice with LCMV induced a virus-specific type 1 cytokine response as determined by in vitro cytokine secretion patterns as well as by in vivo intracellular cytokine staining of LCMV-specific CD4+ TCR transgenic T cells that had clonally expanded in LCMV-infected IL-12-deficient recipient mice. In addition, LCMV- and VSV-specific IgG responses exhibited normal serum IgG2a/IgG1 ratios, demonstrating again virus-specific CD4+ T cell induction of type 1 phenotype in IL-12-deficient mice upon viral infection. LCMV and VSV immune mice were found to be protected against challenge immunization with recombinant vaccinia viruses expressing either the LCMV- or the VSV-derived glycoprotein, respectively. This protection is known to be mediated by T cell-secreted type 1 cytokines IFN-gamma and TNF-alpha. In contrast, IL-12-deficient mice showed impaired abilities to control infection with the facultative intracellular bacterium Listeria monocytogenes at early time points after infection. However, at later time points of infection, IL-12-deficient mice were able to clear infection. These findings may indicate that viruses are able to induce type 1 T cell responses in the absence of IL-12 as opposed to some bacterial or parasitical infections that are crucially dependent on the presence of IL-12 for the induction of type 1 immune responses.

Dendritic cells efficiently induce protective antiviral immunity.

Cytotoxic T lymphocytes (CTL) are essential for effective immunity to various viral infections. Because of the high speed of viral replication, control of viral infections imposes demanding functional and qualitative requirements on protective T-cell responses. Dendritic cells (DC) have been shown to efficiently acquire, transport, and present antigens to naive CTL in vitro and in vivo. In this study, we assessed the potential of DC, either pulsed with the lymphocytic choriomeningitis virus (LCMV)-specific peptide GP33-41 or constitutively expressing the respective epitope, to induce LCMV-specific antiviral immunity in vivo. Comparing different application routes, we found that only 100 to 1,000 DC had to reach the spleen to achieve protective levels of CTL activation. The DC-induced antiviral immune response developed rapidly and was long lasting. Already at day 2 after a single intravenous immunization with high doses of DC (1 x 10(5) to 5 x 10(5)), mice were fully protected against LCMV challenge infection, and direct ex vivo cytotoxicity was detectable at day 4 after DC immunization. At day 60, mice were still protected against LCMV challenge infection. Importantly, priming with DC also conferred protection against infections in which the homing of CTL into peripheral organs is essential: DC-immunized mice rapidly cleared an infection with recombinant vaccinia virus-LCMV from the ovaries and eliminated LCMV from the brain, thereby avoiding lethal choriomeningitis. A comparison of DC constitutively expressing the GP33-41 epitope with exogenously peptide-pulsed DC showed that in vivo CTL priming with peptide-loaded DC is not limited by turnover of peptide-major histocompatibility complex class I complexes. We conclude that the priming of antiviral CTL responses with DC is highly efficient, rapid, and long lasting. Therefore, the use of DC should be considered as an efficient means of immunization for antiviral vaccination strategies.

On the key role of secondary lymphoid organs in antiviral immune responses studied in alymphoplastic (aly/aly) and spleenless (Hox11(-)/-) mutant mice.

The role of the spleen and of other organized secondary lymphoid organs for the induction of protective antiviral immune responses was evaluated in orphan homeobox gene 11 knockout mice (Hox11(-/-)) lacking the spleen, and in homozygous alymphoplastic mutant mice (aly/aly) possessing a structurally altered spleen but lacking lymph nodes and Peyer's patches. Absence of the spleen had no major effects on the immune response, other than delaying the antibody response by 1-2 d. In aly/aly mice, the thymus-independent IgM response against vesicular stomatitis virus (VSV) was delayed and reduced, whereas the T-dependent switch to the protective IgG was absent. Therefore, aly/aly mice were highly susceptible to VSV infection. Since aly/aly spleen cells yielded neutralizing IgM and IgG after adoptive transfer into recipients with normally structured secondary lymphoid organs, these data suggest that the structural defect was mainly responsible for inefficient T-B cooperation. Although aly/aly mice generated detectable, but reduced, CTL responses after infection with vaccinia virus (VV) and lymphocytic choriomeningitis virus (LCMV), the elimination of these viruses was either delayed (VV) or virtually impossible (LCMV); irrespective of the dose or the route of infection, aly/aly mice developed life-long LCMV persistence. These results document the critical role of organized secondary lymphoid organs in the induction of naive T and B cells. These structures also provide the basis for cooperative interactions between antigen-presenting cells, T cells, and B cells, which are a prerequisite for recovery from primary virus infections via skin or via blood.

Multiple immune abnormalities in tumor necrosis factor and lymphotoxin-alpha double-deficient mice.

To investigate the roles of tumor necrosis factor (TNF) and lymphotoxin (LT)-alpha in the development and function of the immune system, the Tnf and Ltalpha genes were simultaneously inactivated in mice by homologous recombination. These mutant mice are highly susceptible to Listeria monocytogenes infection and resistant to endotoxic shock induced by the combined administration of D-galactosamine (D-GaIN) and lipopolysaccharide (LPS). Their splenic microarchitecture is disorganized, characterized by the loss of the clearly defined marginal zone, ill defined T and B cell areas, and absence of MAdCAM-1 and reduced ICAM-1, VCAM-1 and Mac-1 expression. They are devoid of peripheral lymph nodes and Peyer's patches, and show a strong reduction of IgA+ plasma cells in the intestinal lamina propria. The alymphoplasia is accompanied by a marked B lymphocytosis and reduced basal lg levels. Ig depositions in the renal glomerulus and a strong up-regulation of MHC class I antigen expression on endothelial cells of different tissues are observed. The primary humoral immune response towards sheep red blood cells reveals a defective IgG isotype switch, while that against vesicular stomatitis virus is normal. The cytotoxic T cell responses are attenuated, although still effective, against vaccinia, lymphocytic choriomeningitis virus (LCMV-ARM) and LCMV-WE. In conclusion, the combined inactivation of Tnf and Ltalpha confirms their essential role in the normal development and function of the immune system.

Glycosylation of acute phase proteins and interleukins following hip arthroplasty. Inflammation parameters studied in 10 patients.

We analyzed changes in glycosylation and serum concentrations of alpha 1-acid glycoprotein (AGP), antichymotrypsin (AC), interleukin-6 (IL-6), soluble interleukin-2 receptor (sIL-2R) and C-reactive protein (CRP) following hip arthroplasty. Glycosylation of AGP and AC showed an increased reactivity to concanavalin A between postoperative Day 2 and Day 5 and Day 10, respectively. Serum levels of AGP and AC increased at the earliest on Day 5. The AC levels returned to baseline by Day 10. AGP, however, exhibited increased values beyond Day 14. CRP levels were elevated at Day 2 and remained increased beyond Day 14. sIL2R showed increased values at Days 5, 10 and 14. IL-6 was the first parameter to increase, and it returned to baseline in less than 5 days.

[Interleukin-6 (IL-6), soluble interleukin-2-receptor (sIL-2R) and microheterogeneity of alpha-! acid glycoprotein (AGP): new markers of the acute-phase reaction?]. / Interleukin-6 (IL-6), löslicher Interleukin-2-Rezeptor (sIL-2R) und Mikroheterogenität des alpha-1 sauren Glykoproteins (AGP): neue Marker der Akut-Phase-Reaktion?

Cytokines and the different glycosylation profiles of some acute phase proteins appear to be of great value in investigating the activity of inflammatory rheumatic diseases. Using an ELISA to measure the serum concentration of sIL-2R and IL-6 and an affinity electrophoresis with Concanavalin A as a lectin to determine the microheterogenity of the alpha-1-acid-glycoprotein (AGP), we tested the sera of 63 patients with various rheumatic and infectious diseases and 17 healthy persons and compared the results with the usual markers of inflammation, e.g. erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), and with the clinical activity of the disease. ESR, CRP and sIL-2R were significantly elevated (p less than 0.001) in seropositive rheumatoid arthritis (RA) and in acute bacterial infection. ESR and CRP showed a better correlation with the clinical activity of RA than sIL-2R. Marked elevation of IL-6 was found only in 30% of RA patients in the early stage of the acute phase reaction (APR). The AGP reactivity coefficient (AGP-RC) was significantly decreased in RA (p less than 0.01) but increased in bacterial infections (p less than 0.001). Our results show that there is no advantage in measuring sIL-2R in the routine diagnosis of rheumatic diseases. Raised IL-6 levels seem to indicate an early stage of APR. If ESR and CRP are elevated, the AGP-RC helps to differentiate between infection and chronic inflammatory rheumatic diseases.