The B-cell activation pathway in human systemic lupus erythematosus: Imbalancedin vitro production of lymphokines and association with serum analytical findings

Recent knowledge of B-lymphocyte physiology has clarified the role of T cell-derived lymphokines in clonal proliferation and differentiation of B-cell responses. Lymphokine production was analyzed in 19 systemic lupus erythematosus (SLE) patients and sex- and age-matched controls in relation to clinical activity and steroid treatment. Whenin vitro production of interleukin-2 (IL-2) and B-cell growth factor (BCGF) was tested, both activities were found to be diminished in the group of patients (P<0.01), while B-cell differentiation factor (BCDF) activity was higher in this group with respect to normal controls (P<0.01). Interestingly enough, thisin vitro BCDF synthesis was positively correlated with clinical activity regardless of low-dose steroid treatment. A correlation was also found between BCDF production and the levels of IgG (r=0.64,P<0.01), anti-DNA antibodies (r=0.52,P<0.05), and the IgG/IgM ratio (r=0.7,P<0.01) in serum. Implications of these abnormal T-lymphocyte functions in SLE with respect toin vivo B-cell function are discussed.     

Reactivation of Epstein-Barr virus in Sj?gren''s syndrome

Summary Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by severe dryness of the eyes and mouth, resulting from lymphocytic infiltration of the lacrimal and salivary glands. SS may exist as a primary condition (primary SS, 1° SS) or as a secondary condition (2° SS) in association with rheumatoid arthritis, systemic lupus erythematosus, or progressive systemic sclerosis. In some 1° SS patients, there may be involvement of the extraglandular organs, including skin, kidney, liver, lung and nervous system. Furthermore, these patients may develop a lymphoproliferative syndrome that includes lymphadenopathy and increased risk of lymphoma. In the pathogenesis of SS, a role for Epstein-Barr virus (EBV) has been suggested because: (a) EBV is present in salivary gland epithelial cells of normal individuals and exaggerated immune responses against EBV could play a role in the destruction of salivary glands in SS; (b) SS salivary gland biopsies contain increased levels of EBV DNA in comparison to normal salivary glands, indicating viral reactivation and inability of lymphoid infiltrates to control EBV replication in SS patients; and (c) salivary gland epithelial cells in SS patients express high levels of HLA-DR antigens and may present EBV-associated antigens to immune T cells in SS patients. Therefore, SS may represent a situation in which genetically predisposed individuals (i. e., HLA-DR3-DQA4-DQB2) have a persistent but ineffectual T cell immune response against EBV at its site of latency. Among 14 non-Hodgkin's lymphomas that developed in SS patients, EBV DNA was detected in increased amounts in the tumor tissue of one patient. Characterization of this tumor DNA revealed: (a) polyclonal immunoglobulin gene rearrangements; (b) EBV DNA with an unusual restriction fragment length polymorphism pattern involving the Bam M fragment; and (c) EBV terminal repeat sequences suggestive of viral replication, similar to those reported in EBV lymphomas occurring in other immunocompromised individuals. Early recognition of this clinical problem may allow beneficial use of antiviral agents.     

Identifying recent HIV infections using the avidity index and an automated enzyme immunoassay

We evaluated a procedure for identifying recent HIV infections, using sequential serum samples from 47 HIV-positive persons for whom the seroconversion date could be accurately estimated. Each serum sample was divided into two aliquots: one diluted with phosphate-buffered saline and the other diluted with 1 M guanidine. We assayed the aliquots with the automated AxSYM HIV1/2gO test (Abbott Diagnostics Division), without modifying the manufacturer's protocol. We then calculated the avidity index (AI): the ratio of the sample/cutoff value for the guanidine aliquot to that of the phosphate-buffered saline aliquot. We analyzed 216 serum samples: 34 samples were collected within 6 months of seroconversion (recent seroconversions), and 182 were collected after 6 months. The mean AIs, by time from seroconversion, were 0.68 +/- 0.16 (within 6 months) and 0.98 +/- 0.10 (after 6 months) (P < 0.0001). AI of <0.90 correctly identified 88.2% of recent infections but misclassified as recent infections 13.2% of serum samples collected afterward. The probability of an infection being classified as recent and having AI of > or = 0.90 would be 0.7% in a population with 5% recent infections. AI can identify with a certain degree of accuracy recent HIV infections, and being a quantitative index, it provides different levels of sensitivity and specificity, depending on the selected cutoff value. The standard assay procedure is not modified. This test is simple and inexpensive and could be used for surveillance, decision-making in treatment, and prevention.     

Dopamine enhancement of NMDA currents in dissociated medium-sized striatal neurons: role of D1 receptors and DARPP-32

Dopamine (DA), via activation of D1 receptors, enhances N-methyl-D-aspartate (NMDA)-evoked responses in striatal neurons. The present investigation examined further the properties of this enhancement and the potential mechanisms by which this enhancement might be effected. Dissociated medium-sized striatal neurons were obtained from intact rats and mice or mutant mice lacking the DA and cyclic adenosine 3',5' monophosphate (cAMP)-regulated phosphoprotein of M(R) 32,000 (DARPP-32). NMDA (10-1,000 microM) induced inward currents in all neurons. In acutely dissociated neurons from intact rats or mice, activation of D1 receptors with the selective agonist, SKF 81297, produced a dose-dependent enhancement of NMDA currents. This enhancement was reduced by the selective D1 receptor antagonist SKF 83566. Quinpirole, a D2 receptor agonist alone, produced small reductions of NMDA currents. However, it consistently and significantly reduced the enhancement of NMDA currents by D1 agonists. In dissociated striatal neurons, in conditions that minimized the contributions of voltage-gated Ca(2+) conductances, the D1-induced potentiation was not altered by blockade of L-type voltage-gated Ca(2+) conductances in contrast to results in slices. The DARPP-32 signaling pathway has an important role in D1 modulation of NMDA currents. In mice lacking DARPP-32, the enhancement was significantly reduced. Furthermore, okadaic acid, a protein phosphatase 1 (PP-1) inhibitor, increased D1-induced potentiation, suggesting that constitutively active PP-1 attenuates D1-induced potentiation. Finally, activation of D1 receptors produced differential effects on NMDA and gamma aminobutyric acid (GABA)-induced currents in the same cells, enhancing NMDA currents and inhibiting GABA currents. Thus simultaneous activation of D1, NMDA, and GABA receptors could predispose medium-sized spiny neurons toward excitation. Taken together, the present findings indicate that the unique potentiation of NMDA receptor function by activation of the D1 receptor signaling cascade can be controlled by multiple mechanisms and has major influences on neuronal function.     

Automated spoken dialogue system for hypertensive patient home management

Recent advances in automatic speech recognition and related technologies allow computers to carry on conversations by telephone. We developed an intelligent dialogue system that interacts with hypertensive patients to collect data about their health status. Patients thus avoid the inconvenience of traveling for frequent face to face visits to monitor the clinical variables they can easily measure at home; the physician is facilitated in acquiring patient information and cardiovascular risk, which is evaluated from the data according to noted guidelines. Controlled trials to assess the clinical efficacy are under way.     

Age-dependent changes in CXC chemokine ligand 10 serum levels in euthyroid subjects.

Circulating levels of cytokines are deeply influenced by aging, and few data about serum chemokines are available. The aim of this study was to evaluate the influence of aging on circulating CXCL10. One hundred forty healthy subjects (70 males and 70 females), 10-79 years of age, underwent fasting plasma glucose, total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride, and CXCL8 serum assay. Thyroid hormone testing for thyroid-stimulating hormone (TSH), antithyroglobulin (AbTg), and antithyroperoxidase (AbTPO) autoantibodies and thyroid ultrasonography were performed in all subjects to exclude the presence of clinical or subclinical thyroid disease. Serum CXCL10 levels were assayed in all subjects and found to be increased in 14 of 70 females (20%) and in 4 of 70 males (5.7%) (p = 0.01). In a multiple linear regression model including age, body mass index (BMI), systolic and diastolic blood pressure, glycemia, total cholesterol, HDL, LDL, triglycerides, TSH, AbTPO, AbTg, and CXCL8, only age was significantly related to CXCL10 [C.R. 1.30 (0.28-2.33), p = 0.001]. No relationship was present between CXCL8 serum levels and age, suggesting a specificity of CXCL10 elevation as a function of age. Results of this study, performed in healthy subjects on an age gradient, demonstrate an increase in serum CXCL10 with advancing age overall in females, supporting the hypothesis of enhanced Th1 immune responses in aging.     

The cotton rat: an underutilized animal model for human infectious diseases can now be exploited using specific reagents to cytokines, chemokines, and interferons.

The cotton rat represents the best or only animal model for a large number of human infectious diseases, and it may be unique among small laboratory animals in its susceptibility to several potential agents of bioterrorism. Although the cotton rat is a reliable model to define pathologic changes produced during infection with human pathogens, the lack of specific reagents has precluded a more extensive analysis of the molecular basis of pathogenesis. Here, we report the cloning of 24 cotton rat genes encoding various cytokines, chemokines, and interferons (IFNs). Analysis of the expression of most of these genes was performed by RT-PCR in cotton rat macrophages during treatment with lipopolysaccharide (LPS) and in cotton rat lungs after infection with influenza virus. The availability of these reagents will provide the tools for molecular analysis of pathogenesis and immune responses to a wide variety of pathogens and set the basis for the development of new prophylactic and therapeutic strategies against human infectious diseases.