Persistence of Staphylococcus aureus colonization among individuals with immune-mediated inflammatory diseases treated with TNF-α inhibitor therapy.

OBJECTIVE: We investigated the relationship between Staphylococcus aureus colonization and the use of immunosuppressive therapies in patients with immune-mediated inflammatory diseases (IMIDs). METHODS: We prospectively enrolled IMID patients from the rheumatology and dermatology departments of Oregon Health & Science University. At enrolment, we surveyed patients for S. aureus infection risk factors and those using immune-modulating therapies, and evaluated their colonization status with bilateral nares and inguinal fold cultures. Patients were asked to follow up 6-12 months later for reassessment of colonization status by repeat culture. S. aureus isolates were tested for the presence of methicillin resistance by PCR. RESULTS: We enrolled a total of 548 IMID patients. At enrolment, 219 (40.0%) patients were colonized with S. aureus, of which 27 (12.3%) were methicillin-resistant S. aureus (MRSA). Baseline colonization rates were similar between TNF-α inhibitor users and non-users (40.5% and 39.4%, P = 0.79), but were significantly higher for psoriasis patients compared with those with RA (43.5% and 31.8%, P = 0.02). A total of 384 patients were available for follow-up. Patients who were colonized at enrolment were more likely to be colonized at follow-up if they were treated with TNF-α inhibitors during the study as compared to patients without TNF-α inhibitor exposure [odds ratio (OR) = 2.2 (95% CI 1.1, 4.2), P = 0.02]. CONCLUSION: Patients with psoriasis are more likely to be colonized with S. aureus than patients with RA. Patients who are colonized with S. aureus are more likely to remain colonized if exposed to TNF-α inhibitors.

Abnormal expression of CD20 on IgG4 plasma cells associated with IgG4-related lymphadenopathy.

CONTEXT: Immunoglobulin G4 (IgG4)-related disease is a recently described entity that presents as mass-forming lesions in soft tissue, exocrine glands, and in lymph nodes as IgG4-related lymphadenopathy. The underlying pathologic mechanism of IgG4-related disease is unclear; however, rituximab (an anti-CD20 monoclonal antibody) has been shown to have clinical efficacy. OBJECTIVE: To look for the presence or absence of CD20 on the IgG4-expressing plasma cells in IgG4-related lymphadenopathy. DESIGN: Twelve flow cytometry cases were identified through a retrospective review from the authors' institutions files. Cases were selected by the presence of a lymph node biopsy specimen with increased IgG4 plasma cells by immunohistochemistry and a histologic diagnosis compatible with IgG4-related lymphadenopathy. RESULTS: We report dim CD20 expression on plasma cells in all cases for which a plasma cell population was clearly identified by flow cytometry. These cases were from patients with lymph node biopsy specimens that met published criteria for IgG4-related lymphadenopathy. CONCLUSIONS: This finding may be one potential explanation for the clinical efficacy of rituximab in IgG4-related disease.

gammaA/gamma' fibrinogen inhibits thrombin-induced platelet aggregation.

The minor gammaA/gamma' fibrinogen isoform contains a high affinity binding site for thrombin exosite II that is lacking in the major gammaA/gammaA fibrinogen isoform. We therefore investigated the biological consequences of the gamma' chain binding to thrombin. Thrombin-induced platelet aggregation was inhibited by gammaA/gamma' fibrinogen. Carboxyl terminal peptide fragment gamma'410-427 from the gamma' chain was also inhibitory, with an IC(50) of approximately 200 microM in whole plasma. Deletion of the peptide from either the amino or carboxyl end significantly decreased inhibition. In contrast to thrombin-induced platelet aggregation, aggregation induced by epinephrine, ADP, arachidonic acid, or SFLLRN peptide showed little inhibition by the gamma' peptide. The inhibition of thrombin-induced platelet aggregation was not due to direct inhibition of the thrombin active site, since cleavage of a small peptidyl substrate was 91% of normal even in the presence of 1 mM gamma'410-427. The gamma'410-427 peptide blocked platelet adhesion to immobilized thrombin under both static and flow conditions, blocked soluble thrombin binding to platelet GPIbalpha, and inhibited PAR1 cleavage by thrombin. These results suggest that the gamma' chain of fibrinogen inhibits thrombin-induced platelet aggregation by binding to thrombin exosite II. Thrombin that is bound to the gamma' chain is thereby prevented from activating platelets, while retaining its amidolytic activity.

Efalizumab therapy for atopic dermatitis causes marked increases in circulating effector memory CD4+ T cells that express cutaneous lymphocyte antigen.

Efalizumab is an mAb directed against CD11a, a molecule involved in T-cell activation and extravasation from blood into tissue. Ten patients with severe atopic dermatitis were treated with efalizumab for 84 days, and peripheral blood mononuclear cells were analyzed for expression of activation and adhesion markers. Efalizumab treatment led to decreases in CD11a mean fluorescence intensity (MFI) on naive, central memory, and effector memory CD4+ and CD8+ T cell subsets. MFI for CD18 was decreased in both CD4+ and CD8+ T cells. Percentages of cells positive for cutaneous lymphocyte antigen (CLA) were increased fourfold in all CD4+ and CD8+ T cell subsets. Increases in the percentages of CD4+ and CD8+ T cells expressing beta7 and CD49d were also observed. No significant changes were observed in the percentages of CD4+ and CD8+ T cells that produced either IFN-gamma or IL-4. In summary, efalizumab treatment resulted in (i) decreases in CD11a and CD18 expression in all circulating T-cell subsets and (ii) increases in the percentages of blood T cells expressing tissue homing markers (CLA, beta7, CD49d). These data suggest that blockade of T-cell extravasation into tissue is the major pathway by which efalizumab leads to improvement in cutaneous inflammation.

Dynamics of Neisseria gonorrhoeae attachment: microcolony development, cortical plaque formation, and cytoprotection.

Neisseria gonorrhoeae is the bacterium that causes gonorrhea, a major sexually transmitted disease and a significant cofactor for human immunodeficiency virus transmission. The retactile N. gonorrhoeae type IV pilus (Tfp) mediates twitching motility and attachment. Using live-cell microscopy, we reveal for the first time the dynamics of twitching motility by N. gonorrhoeae in its natural environment, human epithelial cells. Bacteria aggregate into microcolonies on the cell surface and induce a massive remodeling of the microvillus architecture. Surprisingly, the microcolonies are motile, and they fuse to form progressively larger structures that undergo rapid reorganization, suggesting that bacteria communicate with each other during infection. As reported, actin plaques form beneath microcolonies. Here, we show that cortical plaques comigrate with motile microcolonies. These activities are dependent on pilT, the Tfp retraction locus. Cultures infected with a pilT mutant have significantly higher numbers of apoptotic cells than cultures infected with the wild-type strain. Inducing pilT expression with isopropyl-beta-D-thiogalactopyranoside partially rescues cells from infection-induced apoptosis, demonstrating that Tfp retraction is intrinsically cytoprotective for the host. Tfp-mediated attachment is therefore a continuum of microcolony motility and force stimulation of host cell signaling, leading to a cytoprotective effect.

Drug resistance in B-cell chronic lymphocytic leukemia: predictable by in vitro evaluation with a multiparameter flow cytometric cytotoxicity assay.

BACKGROUND: Patients with B-cell chronic lymphocytic leukemia (B-CLL) often demonstrate variable responses to similar treatments. It would be highly desirable to develop a personalized therapeutic strategy for selection of appropriate drugs or regimens based on the drug sensitivity profiles of leukemic cells from individuals. METHODS: We applied a multiparameter flow cytometric drug cytotoxicity assay to evaluate drug effects specifically on B-CLL cells from 43 individuals after leukemic cells were incubated in vitro with fludarabine, chlorambucil, cladribine, or prednisolone. RESULTS: We demonstrated that different B-CLL cell populations from 43 individuals showed a marked variability in drug sensitivity. In vitro resistance to fludarabine was greatest in B-CLL cells with deletions of p53, a cytogenetic abnormality that is almost invariably associated with a poor therapeutic response clinically. CONCLUSIONS: In vitro drug sensitivity profiles analyzed by a multiparameter flow cytometric cytotoxicity assay may serve as a tool to facilitate individualized selection of appropriate drugs for treatment in B-CLL. Prospective trials will be needed to validate the clinical utility of this flow cytometric cytotoxicity assay.

Clonal isolation of chlamydia-infected cells using flow cytometry.

This manuscript describes a new technique for the microbiological cloning of chlamydia-infected cells using a fluorescence activated cell sorter (FACS). The approach exploits chlamydial acquisition of the fluorescent, Golgi-specific, stain 6-((N-7-(-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-hexanoyl)sphingosine (C6-NBD-cer). This fluorescent lipid is delivered from the Golgi apparatus to the chlamydial inclusion membrane and then to the developmental forms within the inclusion in living, infected cells. Labeling with C6-NBD-cer results in easily identifiable chlamydial inclusions that can then be analyzed and sorted by FACS. This technique was used successfully to sort individual chlamydia-infected cells into individual wells of a culture dish and, in this experimental system, resulted in the isolation of cloned chlamydial isolates. FACS-based sorting was used to isolate clonal populations of prototype strains from Chlamydia trachomatis, C. caviae and C. suis. Recent clinical isolates were also successfully cloned using FACS. The procedure is simple and rapid, with single cloning cycles being completed 24 h post-culture of a sample. It is anticipated that FACS-based sorting of live chlamydia-infected cells will be a significant technical tool for the isolation of clonal populations of any chlamydial strain.

Inflammatory disease and lymphomagenesis caused by deletion of the Myc antagonist Mnt in T cells.

Mnt is a Max-interacting protein that can antagonize the activities of Myc oncoproteins in cultured cells. Mnt null mice die soon after birth, but conditional deletion of Mnt in breast epithelium leads to tumor formation. These and related data suggest that Mnt functions as a tumor suppressor. Here we show that conditional deletion of Mnt in T cells leads to tumor formation but also causes inflammatory disease. Deletion of Mnt caused increased apoptosis of thymic T cells and interfered with T-cell development yet led to spleen, liver, and lymph node enlargement. The proportion of T cells in the spleen and lymph nodes was reduced, and the numbers of cells in non-T-cell immune cell populations were elevated. The disruption of immune homeostasis is linked to a strong skewing toward production of T-helper 1 (Th1) cytokines and enhanced proliferation of activated Mnt-deficient CD4+ T cells. Consistent with Th1 polarization in vivo, extensive intestinal inflammation and liver necrosis developed. Finally, most mice lacking Mnt in T cells ultimately succumbed to T-cell lymphoma. These results strengthen the argument that Mnt functions as a tumor suppressor and reveal a critical and surprising role for Mnt in the regulation of T-cell development and in T-cell-dependent immune homeostasis.

Mycobacterium avium in pygmy rabbits (Brachylagus idahoensis): 28 cases.

The Columbia basin subpopulation of pygmy rabbit Brachylagus idahoensis was listed as endangered by the United States Fish and Wildlife Service in November 2001, and no pygmy rabbits have been seen in the wild since spring 2002. Captive propagation efforts have attempted to increase population size in preparation for reintroduction of animals into central Washington. Disseminated mycobacteriosis due to Mycobacterium avium has been the most common cause of death of adult captive pygmy rabbits. Between June 2002 and September 2004, mycobacteriosis was diagnosed in 28 captive adult pygmy rabbits (representing 29% of the captive population), in contrast to 18 adult pygmy rabbits dying of all other causes in the same time period. Antemortem and postmortem medical records were evaluated retrospectively to describe the clinical course of mycobacteriosis in pygmy rabbits, physical examination findings, and diagnostic test results in the diagnosis of mycobacteriosis in pygmy rabbits. Various treatment protocols, possible risk factors for mortality, and recommendations for prevention of mycobacteriosis were evaluated also. Compromised cell-mediated immunity appears to be the best explanation at this time for the observed high morbidity and mortality from mycobacterial infections in pygmy rabbits.

A robust ratio metric method for analysis of Zap-70 expression in chronic lymphocytic leukemia (CLL).

Since Zap-70 expression in chronic lymphocytic leukemia (CLL) cells correlates with a lack of somatic mutation of the immunoglobulin variable heavy chain (IgVH) genes, it has been proposed as a surrogate marker for disease prognosis. However, published studies of Zap-70 expression have used different commercial antibodies and analytic strategies. This study was undertaken to determine if any strategy was broadly applicable in a clinical flow cytometry laboratory. Expression of Zap-70 was determined in 37 CLL patients using four different commercial antibodies. T, NK, and CLL cells were identified by immunophenotyping along with Zap-70 expression. Data was analyzed in terms of both percent of CLL cells expressing Zap-70 and the ratio of Zap-70 expression in CLL cells compared to that in T + NK cells. Three Zap-70 antibodies showed wide ranges of Zap-70 expression as a percentage of tumor cells, while a fourth gave consistently elevated results. Comparing the percent Zap-70 expression with any two antibodies gave poor correlations (r(2) = 0.45-0.63). Our results indicated that the previous analytical strategies were not reproducible. A ratio metric is proposed, which gave better correlations (r(2) as high as 0.95) and would allow separation of CLL patients with elevated or decreased Zap-70 expression.

Alterations in T-cell subset frequency in peripheral blood in obesity.

BACKGROUND: Obesity affects the regulation of immune and inflammatory responses. This study characterizes differences in peripheral blood lymphocyte phenotype in obese humans. METHODS: Frequencies of lymphocyte subsets among peripheral blood mononuclear cells were compared between 10 obese (BMI > or = 35) and 10 lean subjects, as determined by antibodies directed against cluster differentiation (CD) markers. RESULTS: Obese patients demonstrated an increased frequency of CD3+CD4+ T-cells (mean difference 12%, P=0.004), a decreased frequency of CD3+CD8+ T-cells (mean difference 9.4%, P=0.016) and an increased frequency of CD3+CD8+CD95+ T-cells (mean difference 13.3%, P=0.032). No other differences among T-cell or monocyte subsets were noted. CONCLUSIONS: Obesity is associated with alterations in frequencies of peripheral CD4+ and CD8+ T-cells and aberrations in the expression of CD95 among CD8+ T-cells. These data suggest both CD4+ and CD8+ T-cell compartments, as well as the regulation of CD95 expression on CD8+ T-cells, as targets for further study into obesity's effects on the immune system.

Diagnostic usefulness of aberrant CD22 expression in differentiating neoplastic cells of B-Cell chronic lymphoproliferative disorders from admixed benign B cells in four-color multiparameter flow cytometry.

The diagnosis of B-cell chronic lymphoproliferative disorders is a great challenge when made in a background of polyclonal B cells. We studied the diagnostic usefulness of aberrant CD22 expression for differentiating neoplastic from benign B cells by 4-color flow cytometry. Of 56 cases of B-cell chronic lymphoproliferative disorders, we found that neoplastic cells showed aberrant CD22 expression in 39 (70%) of 56 cases, including chronic lymphocytic leukemia, mantle cell lymphoma, marginal zone lymphoma, hairy cell leukemia, and follicular lymphoma. In 4 cases, monoclonality was detected definitively only by evaluating the immunoglobulin light chain restriction in B cells with aberrant CD22 expression because numerous polyclonal B cells were present. Aberrant CD22 expression is a useful marker for detection of monoclonal B cells admixed with numerous benign polyclonal B cells.

Sustained engraftment post bone marrow transplant despite anti-platelet antibodies in Glanzmann thrombasthenia.

BACKGROUND: Patients with Glanzmann thrombasthenia (GT) have normal platelet counts but abnormal platelet aggregation and carry the risk of life-threatening bleeding. We report three patients who received bone marrow transplantation (BMT) for type I GT and discuss the risk and management of anti-platelet antibodies. PATIENTS AND RESULTS: Diagnosis of GT was made through abnormal platelet aggregation studies or the absence of GPIIb/IIIa by flow cytometry. All patients had severe bleeding requiring multiple red blood cell transfusions. One patient received an unrelated donor transplant and two received matched sibling donor transplants following conditioning therapy with busulfan, cyclophosphamide, and fludarabine. Two patients developed an anti-platelet antibody, treated in one with intravenous immune globulin (IVIG). Engraftment of white blood cells and platelets was achieved on day +13 to +14 and +17 to +25, respectively. Complete donor chimerism and GPIIb/IIIa+ platelets are sustained at +22 to +30 months post transplant. CONCLUSIONS: In summary, patients with GT and history of severe hemorrhage can be cured with BMT, but the presence of anti-platelet antibodies should be sought and platelet transfusions minimized prior to transplant. IVIG may be helpful in cases of refractory immune thrombocytopenia related to anti-platelet antibodies. Improvement in transplant-related complications with current transplant regimens allows consideration of BMT for life-threatening non-malignant disorders such as GT.

Direct enumeration and functional assessment of circulating dendritic cells in patients with liver disease.

Chronic liver disease has been shown to be associated with diminished humoral and cellular immune function. Although antigen-presenting cells (APC) that initiate immune responses include various cells (B cells, endothelial cells, macrophages, etc.), the dendritic cell (DC) is a professional APC that activates naive T cells most efficiently. To examine the frequency and function of DCs in chronic liver disease, we studied circulating DCs from a cohort of 112 subjects (23 normal subjects, 29 subjects who had spontaneously recovered from hepatitis C virus [HCV] infection, 30 chronically infected HCV patients, and 30 patients with liver disease unrelated to HCV infection). Our analyses revealed significant reduction in both circulating myeloid (mDC) and plasmacytoid dendritic cells (pDC) in patients with liver disease. In contrast, examination of subjects with spontaneously resolved HCV infection revealed no significant difference in either circulating mDCs or pDCs. We found an inverse correlation with serum alanine aminotransferase (ALT) levels and both mDCs and pDCs frequency. In a subset of patients for whom intrahepatic cells were available, paired analysis revealed enrichment for DCs within the intrahepatic compartment. Interferon alfa (IFN-alpha) production in response to influenza A and poly (I:C) correlated with the frequency of circulating DCs, although IFN-alpha production was comparable on a per-DC basis in patients with liver disease. In conclusion, patients with liver disease exhibit a reduction in circulating DCs. Considering that DCs are essential for initiation and regulation of innate and adaptive immunity, these findings have implications for both viral persistence and liver disease.

Estrogen treatment induces a novel population of regulatory cells, which suppresses experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is a debilitating neurological disease characterized by a progressive loss of motor and sensory function, eventually leading to paralysis and death. The primary cause of neurological impairment is demyelination of the central nervous system (CNS) caused by an inflammatory autoimmune response. Previous studies have shown that the severity of MS is reduced during pregnancy, suggesting that the increased level of sex hormones may reduce the autoimmune response. Recently, we have shown that estrogen treatment confers protection from experimental autoimmune encephalomyelitis (EAE), which is an animal model for MS. However, the cellular basis of estrogen's action remains unknown. In the current study, we demonstrate that estrogen treatment led to the induction of a novel subpopulation of regulatory cells in spleen and CNS, which also occurs naturally in pregnant mice. These previously uncharacterized cells display a low level expression of CD45 (CD45(dim)) and no detectable expression of many cell surface markers related to TCR signaling, including CD3 and TCR. However, these cells retained expression of VLA-4, an extracellular protein involved in cellular migration. Several lines of evidence suggest that these novel cells, defined as CD45(dim)VLA-4(+) cells, may play a role in the protective effects of estrogen in EAE. Injection of purified CD45(dim)VLA-4(+) cells conferred protection from spontaneous EAE (Sp-EAE). In contrast, injection of CD45(high)VLA-4(+) cells exacerbated the disease course. CD45(dim)VLA-4(+) cells also suppressed antigen-specific proliferation of primed lymphocytes in coculture. A better understanding of how CD45(dim)VLA-4(+) cells suppress the harmful immune response of EAE may help in explaining the induction of immune tolerance during pregnancy and lead to novel therapeutic approaches to combat MS and other autoimmune diseases.

Functional assay for human CD4+CD25+ Treg cells reveals an age-dependent loss of suppressive activity.

CD4+CD25+ regulatory T cells (Treg cells) prevent T cell-mediated autoimmune diseases in rodents. To develop a functional Treg assay for human blood cells, we used FACS- or bead-sorted CD4+CD25+ T cells from healthy donors to inhibit anti-CD3/CD28 activation of CD4+CD25- indicator T cells. The data clearly demonstrated classical Treg suppression of CD4+CD25- indicator cells by both CD4+CD25(+high) and CD4+CD25(+low) T cells obtained by FACS or magnetic bead sorting. Suppressive activity was found in either CD45RO- (naive) or CD45RO+ (memory) subpopulations, was independent of the TCR signal strength, required cell-cell contact, and was reversible by interleukin-2 (IL-2). Of general interest is that a wider sampling of 27 healthy donors revealed an age- but not gender-dependent loss of suppressive activity in the CD4+CD25+ population. The presence or absence of suppressive activity in CD4+CD25+ T cells from a given donor could be demonstrated consistently over time, and lack of suppression was not due to method of sorting, strength of signal, or sensitivity of indicator cells. Phenotypic markers did not differ on CD4+CD25+ T cells tested ex vivo from suppressive vs. nonsuppressive donors, although, upon activation in vitro, suppressive CD4+CD25+ T cells had significantly higher expression of both CTLA-4 and GITR than CD4+CD25- T cells from the same donors. Moreover, antibody neutralization of CTLA-4, GITR, IL-10, or IL-17 completely reversed Treg-induced suppression. Our results are highly consistent with those reported for murine Treg cells and are the first to demonstrate that suppressive activity of human CD4+CD25+ T cells declines with age.

The effect of hypnotic-guided imagery on psychological well-being and immune function in patients with prior breast cancer.

OBJECTIVE: To determine the effect of hypnotic-guided imagery on immune function and psychological parameters in patients being treated for Stage I or II breast cancer. METHODS: To determine the effects of hypnotic-guided imagery on immune function and psychological parameters, the following study was undertaken. Psychological profiles, natural killer (NK) cell number and activity were measured at baseline, after the 8-week imagery training program and at the 3-month follow-up. RESULTS: There were significant increases in improvement in depression (P<.04) and increase in absolute number of NK cells, but these were not maintained at the 3-month follow-up. Hypnotic-guided imagery did cause some transient changes in psychological well-being and immune parameters. However, these changes were not retained after the treatment ended. CONCLUSIONS: Many studies during the last 15 years have demonstrated interactions between the central nervous and the immune systems. While a negative effect of stress on immune responses has been demonstrated, there have also been published reports that psychological treatments can positively alter the immune system. However, given the complexities of immune system kinetics, the transient nature of any psychological effect and the insensitivity of immune assays, our study indicates that there is a role for hypnotic-guided imagery as an adjuvant therapy.

Frequencies of HCV-specific effector CD4+ T cells by flow cytometry: correlation with clinical disease stages.

Hepatitis C virus (HCV) is the leading cause of chronic hepatitis, affecting approximately 2% of the world's population. The immune mechanisms responsible for the highly variable natural history in a given individual are unknown. We used a multiparameter flow cytometric technique to functionally and phenotypically characterize HCV-specific effector T cells in the peripheral blood of 32 individuals with different stages of hepatitis C disease (resolved, mild chronic, advanced chronic) and normal controls. We found the highest frequencies of virus-specific effector cells with an activated memory phenotype (CD45RO+CD69+) in subjects who had resolved HCV infection, either spontaneously or with antiviral therapy. Effector cells from patients with resolved infection produced Th1 type cytokines following stimulation with nonstructural antigens (NS3 and NS4), whereas effector cells from chronically infected patients produced Th1 type cytokines predominantly following stimulation with the HCV core antigen. Stimulation with superantigen staphylococcal enterotoxin (SEB) induced the same levels of cytokine production in the different patient groups. Among the HCV-seropositive patients, viral load inversely correlated with the Th1 effector cell response to NS3. Interleukin (IL)-4 was produced only in response to the control antigens, but not in response to the HCV recombinant proteins. Taken together, these findings suggest that a vigorous HCV-specific CD4+ Th1 response, particularly against the nonstructural proteins of the virus, may be associated with viral clearance and protection from disease progression. Prospective studies using this new flow cytometric assay will be required to determine whether antiviral therapy modifies the frequency, specificity, and function of these virus-specific effector cells.