Effect of Mirtazapine on Thyroid Hormones in Adult Patients with Major Depression

Hypothalamic pituitary thyroid (HPT) axis abnormalities and alterations in major depression are reported in literature. The aim of our study was to evaluate the effect of mirtazapine on thyroid hormones after 6 months of therapy in a sample of adult outpatients with Major Depression (MD). 17 adult outpatients (7 men, 10 women) with MD according to DSM-IV criteria, were included in the study. All participants had to have met criteria for a major depressive episode with a score of at least 15 on the Hamilton Depression Rating Scale (HAM-D). Fasting venous blood samples were obtained for determination of serum Thyroid Stimulating Hrmone (TSH), Free T3 (FT3) and Free T4 (FT4) concentrations both at baseline and after 6 months of therapy. HAM-D scores decreased significantly from the first day of treatment to the end of the treatment period (p<0.001) and twelve patients (70.6%) were classified as responders. A significant increase in FT3 concentrations was found between baseline and the end of treatment period (P=0.015) whereas FT4 concentrations decreased (P=0.046). No significant changes were found in TSH levels. Higher FT4 concentrations at baseline predicted higher HAM-D scorers both at baseline and at the end of the treatment period. Furthermore, higher FT3 concentrations at endpoint were found to be predictors of lower HAM-D scores. Long-term treatment with mirtazapine increases FT3 levels and decreases FT4 maybe involving the deiodination process of T4 into T3.

A Retrospective Evaluation of the Inflammatory Marker C-Reactive Protein (CRP), Cholesterol and High-Density Lipoproteins in Patients with Major Depression: Preliminary Findings

The aim of this study was to retrospectively evaluate the role of C-reactive protein, total cholesterol and high-density lipoprotein cholesterol in patients suffering from Major Depression (MD). Data of C-reactive protein, total cholesterol (TC) and high-density lipoprotein cholesterol of 37 adult outpatients (17 men, 20 women) with a DSM-IV diagnosis of MD were analyzed. Depression was measured with the 17-item Hamilton Depression Rating Scale (HAM-D) and with the Beck Depression Inventory (BDI). Suicide risk was evaluated with the Scale of Suicide Ideation (SSI). Patients with a lifetime history of attempted suicide were categorized as having higher suicide risk. Higher suicide risk patients showed higher C-reactive protein levels and lower high-density lipoprotein cholesterol levels than lower suicide risk patients whereas total cholesterol levels were not statistically different. C-reactive protein positively correlated with BDI, HAM-D, SSI scores and with number of previous depressive episodes. High-density lipoprotein cholesterol correlated inversely with BDI, HAM-D and SSI scores, whereas, no significant correlations were found between Total Cholesterol and other variables including C-reactive protein. In linear regression models, C-reactive protein was predictor of more severe depression and increased suicide risk. Lower high-density lipoprotein cholesterol levels were significantly predictive of increased suicide risk.

Purification and biochemical characterization of a novel cysteine protease of Entamoeba histolytica

Cysteine proteases are important virulence factors of Entamoeba histolytica, the causative agent of amoebiasis. A novel cysteine protease from parasite extracts was purified 15-fold by a procedure including concanavalin A-Sepharose, hydroxylapatite and DEAE-Sepharose chromatography. The purification resulted in the obtainment of an homogeneous protein with a molecular mass of 66 kDa on native PAGE. In 10% SDS/PAGE, three bands of 60, 54 and 50 kDa were evident. Each of the three specific mouse antisera raised against these proteins showed cross-reactivity with the three bands obtained from the purified eluate. The N-terminal sequencing of the first 10 amino acids from the three proteins showed 100% identity. These results support the hypothesis of a common precursor for the 60, 54 and 50-kDa proteins. Protease activity of the purified enzyme was demonstrated by electrophoresis in a gelatine-acrylamide copolymerized gel. Its activity was quantified by cleaving a synthetic fluorogenic peptide substrate such as N-carbobenzyloxy-arginyl-arginyl-7-amido-4-methylcoumarin. The optimum pH for the protease activity was 6.5; however, enzymatic activity was observed between pH 5 and pH 7.5. Typical of cysteine proteases, the enzyme was inhibited by 4-[(2S, 3S)-carboxyoxiran-2-ylcarbonyl-L-leucylamido]butylg uanidine and iodoacetamide, and activated by free sulfhydryl groups. The cellular location of the enzyme was examined on trophozoites before and after contact with red blood cells using indirect immunofluorescence and cellular fractionation. The 60-kDa cysteine protease translocated to the amoebic surface upon the interaction of trophozoites with red blood cells. This result provided evidence for participation of the 60-kDa protease in erythrophagocytosis.

Shrinkage of a PRL-secreting pituitary macroadenoma resistant to cabergoline

Cabergoline decreases both serum PRL levels and size of prolactinomas, including some tumors resistant to other dopamine-agonists. It is common observation that the shrinkage of the adenoma is preceded by suppression of PRL levels. A minority of patients, who do not show a significant decrease of PRL after a short trial with dopamine-agonists, undergoes neurosurgery or radiotherapy. We report on the case of a 14-year-old girl with a huge prolactinoma who showed, during cabergoline treatment (0.5 mg twice a week), a significant shrinkage of the pituitary mass but no decrease of the very high PRL values. She was referred to us after partial removal of the suprasellar extension of the pituitary tumor. The post-surgical evaluation showed very high PRL levels (9352 microg/l; 20941 microg/l before surgery), which did not decrease during the 2-year treatment with cabergoline (nadir value: 8735 microg/l). However, one month after the beginning of therapy, MRI showed a significant shrinkage of the tumor (tumor volume 5.7 ml, compared with 45.1 ml prior to surgery and 24.4 ml after surgery). Subsequently MRIs demonstrated a progressive reduction of the size with a complete disappearance of the suprasellar and parasellar tissue (tumor volume 1.8, 0.9 and 0.2 ml, at 3, 6 and 12 months, respectively). The MRI performed at the 24th month showed a secondary empty sella, with residual tumor tissue in the right sphenoidal sinus. Increasing cabergoline, up to 3 mg a week, failed to induce any decrease of PRL levels. In conclusion, in such macroprolactinomas the shrinkage of tumor is not strictly correlated with (or it is partially dissociated from) the inhibition of PRL hypersecretion. The choice of other therapeutic options in cabergoline-resistant macroprolactinomas needs careful neuroradiological evaluation after a short trial of pharmacological treatment.

Expression of the hepatocyte growth factor and c-met in normal thyroid, non-neoplastic, and neoplastic nodules

We have examined the coexpression of hepatocyte growth factor (HGF) and its receptor (HGF-R or c-met) in an archival series of 63 paraffin-embedded thyroid specimens plus one lymph node metastasis. By immunocytochemistry, we found undetectable expression of both the ligand and the receptor in 10 normal thyroids and 9 nonpapillary malignant nodules [5 follicular carcinomas, 1 poorly differentiated (insular) carcinoma, 3 undifferentiated (anaplastic) carcinomas]. Of 10 non-neoplastic nodules (colloid nodules) and 17 benign neoplastic nodules, 3 of 10 colloid nodules, 2 of 10 follicular adenomas, and 2 of 7 oncocytic adenomas showed a weak but distinct staining (1+ score in a scale from 0 to 4+) of both HGF and c-met in a modest proportion of cells (1% to 3%). In these 7 cases, expression of HGF was always stromal and expression of c-met limited to the membrane of the follicular cells. Of 3 malignant nodules derived from aberrant growth of the parafollicular C cells (medullary thyroid cancer or MTC), 2 were positive (6% of cells). In these 2 cases, the expression of HGF (3+) was not stromal, but in both the membrane and cytoplasm of the parafollicular cells, while that of c-met (3+) was restricted to the membrane. In contrast to all of the above, of 14 papillary carcinomas (PTC) encompassing 5 histological variants (conventional; follicular; oncocytic; with foci of solid growth; diffuse sclerosing) plus 1 neck lymph node metastasis of 1 conventional PTC, 12 (86%) expressed HGF, and 13 (93%) expressed c-met. With the exception of 2 negative cases, HGF was detected in 15% to 46% of the cells. The highest percentage (46%) pertained to conventional PTC cases with abundant peritumoral lymphocyte infiltration, indicating that some lymphokine(s) may recruit PTC cells for HGF expression in a paracrine fashion. With the exception of one negative case, c-met was found in 43% to 80% of the cells, both at levels from intense (3+) to very intense (4+). The immunostaining for HGF was stromal in 25%, membranous in 8%, cytoplasmic in 8%, and both membranous and cytoplasmic in 59% of the PTC-positive cases. The immunostaining for c-met was membranous in 43% and both membranous and cytoplasmic in 57% of the PTC-positive cases. In the lymph node metastasis and in the diffuse sclerosing variant of PTC (the most aggressive variant), the coexpression of HGF/c-met was lost, in that only c-met was expressed on membranes in both cases. We conclude that the HGF/c-met system is activated (by overexpression of both components) in the vast majority of PTC. In most PTC the interaction of HGF and its receptor (c-met) is autocrine, not paracrine.

Long-term symptom patterns in duodenal ulcer: psychosocial factors

Seventy-five patients with recent-onset dyspepsia and endoscopically visible duodenal ulcer underwent psychological evaluation. Following ranitidine treatment, they were reinterviewed periodically for 12 to 76 months (mean 38.6). Ulcer symptoms were present during a mean of 14.9% of follow-up months. Patients did significantly worse if they had a low-status occupation, low education, depression, stressful life events, or abnormal Minnesota Multiphasic Personality Inventory at baseline. Of patients recalling premorbid life stress, those with a normal MMPI had a particularly benign course, whereas those with an abnormal MMPI did particularly poorly (6% versus 29% of months symptomatic: p < 0.04). Age, gender, smoking, drinking, antiinflammatory drugs, pepsinogen, Helicobacter pylori titers, and initial healing had no prognostic effect. Low socioeconomic status, life stress, depression, and psychopathology each predict a relatively poor symptom outcome for duodenal ulcer treated with antisecretory therapy, but psychologically stable individuals who develop an ulcer under stress have an excellent long-term prognosis.

Psychologic predictors of duodenal ulcer healing

We investigated psychologic influences on duodenal ulcer by examining the effect of personality, stress, and mood, measured at diagnosis, on subsequent ulcer healing. Stressful life events, psychopathology (assessed using the Minnesota Multiphasic Personality Inventory), anxiety, depression, smoking, alcohol consumption, nonsteroidal antiinflammatory drug use, and serum pepsinogen I levels were determined immediately after endoscopy showed duodenal ulcer craters in 70 patients with recent onset of symptoms. Endoscopy was repeated following 6 weeks of ranitidine therapy. Six ulcers (8.6%) persisted, and the duodenum remained inflamed in an additional five cases, for a total of 16% with incomplete healing. The only baseline characteristic significantly associated with poor healing was anxiety (p = 0.03 for ulcer persistence, p = 0.02 for incomplete healing). Being in the highest anxiety tertile was associated with a more than fourfold elevation in the risk of incomplete healing (p = 0.02). The association between anxiety and poor healing was not changed by modification of the anxiety score to eliminate gastrointestinal symptom items or by adjustment for serum pepsinogen, sex, or cigarette smoking. Anxiety inhibits the healing of duodenal ulcers treated with adequate antisecretory therapy.

Bile ductopenia following therapy with sulpiride

We report a case of ductopenia associated with cholestatic hepatitis in a 59-year-old woman treated for 41 years for temporal epilepsy. The patient developed jaundice, without any clinical or biochemical features of hypersensitivity, 10 months after the beginning of treatment with sulpiride. Liver biopsy showed ballooning and acidophilic degeneration of the hepatocytes, macrophages packed with lipofuscin, biliary pigment in Kupffer cells, some biliary plugs, confluent necrosis and absence of biliary ducts in all the portal tracts. These features and the presence of foci of cholangiolitis suggest a destructive cholangitis as the pathogenetic mechanism causing ductopenia. Other causes of ductopenia were excluded. Sulpiride is known to produce severe cholestatic jaundice, which we believe is due to ductopenia. The absence of hypersensitivity and the 10-month latency suggest that sulpiride may cause liver damage through a toxic mechanism in genetically susceptible subjects.

Patterns of biologic and psychologic risk factors in duodenal ulcer patients

To clarify whether and how psychologic factors might contribute to peptic ulcer, in this study we addressed the relations between psychologic characteristics and known biologic risk factors among ulcer patients. In 75 patients with recent-onset, symptomatic duodenal ulcer, an index of three potential psychologic risk factors (stressful life events, abnormal Minnesota Multiphasic Personality Inventory, mood disturbance) was examined in relation to historical risk factors (sex, age, seasonality, family history, smoking, alcohol use, coffee consumption, nonsteroidal antiinflammatory drug use), and to blood type, serum pepsinogen I, and Helicobacter pylori antibody titers. The more risk factors in a patient's history, the less likely he or she was to have psychopathology or stress (r = -0.45, p = 0.0007). The mean number of conventional risk factors was 2.7 in patients with all three psychologic risk factors and 4.4 in patients with none; conversely, the mean number of psychologic factors was 0.9 among patients with five or more biologic risk factors and 2.1 among patients with fewer than three risk factors. This negative association was strongest among patients with no previous ulcer history. The psychologic factors also tended to vary inversely with H. pylori antibody titers but not with blood type O or pepsinogen. Duodenal ulcer patients who are atypical in terms of their conventional risk factors are likely to be emotionally fragile, under stress, or both, especially at the time of their first ulcer symptoms. A clinician diagnosing an ulcer in an individual who does not match the usual patient profile should be on the lookout for psychologic factors.

Chronic hepatitis in patients with active hepatitis B virus and hepatitis C virus combined infections: a histological study

OBJECTIVES

To evaluate whether peculiar histological changes are present in liver tissue of patients with chronic hepatitis by hepatitis B and hepatitis C (HBV and HCV) virus combined infections.

METHODS

We studied liver biopsy specimens from 14 HB surface antigen/anti-HCV-positive patients consecutively admitted to hospital because of chronic liver disease from 1987 to 1992. Alcohol abusers, drug addicts, hepatitis delta virus- and HIV-infected subjects were excluded from the study. All of them were positive for serum HBV-DNA and/or intrahepatic HB core antigen and for serum HCV-RNA. Histological examination showed mild or moderate chronic hepatitis in nine cases and severe chronic hepatitis with cirrhosis in five cases. Two additional sets of liver biopsy specimens were also included in the study, consisting of liver samples from 14 patients with chronic liver disease due to active HBV infection alone (group B) and from 14 patients with active HCV infection alone (group C). Cases from group B and C matched for age, sex, and histological diagnosis with those from group B + C. Histological patterns of all the liver specimens of the three groups were re-examined by two authors who scored the found features using a scale from 0 to 3.

RESULTS

No peculiar histological pattern was revealed in group B + C, and most of the detected microscopic features were similarly present in all three groups. Bile duct lesions and well defined lymphoid follicles were found only in liver samples of patients from groups C and B + C. Ground-glass hepatocytes were observed only in cases from the groups B and B + C.

CONCLUSIONS

Histological examination of liver tissue from patients with chronic HBV and HCV combined infection does not show either typical patterns or evidence that this subgroup of chronic viral hepatitis is a more severe form of liver disease than that caused by a single virus infection. The observation in liver samples of peculiar lesions by HBV or HCV infection does not exclude a combined infection by both viruses.

Hepatitis B E antigen detection in formalin-fixed liver biopsy specimens. A tool to investigate wild-type and E-minus variant HBV infection

The aim of this study is to investigate whether hepatitis B e antigen (HBeAg) reactivity can be detected on formalin-fixed, paraffin-embedded liver tissue, and whether immunohistochemical detection of intrahepatic HBeAg may help to distinguish between "wild-type" and "eminus" hepatitis B virus (HBV) infection. Liver biopsy specimens were analyzed from 27 patients with chronic type B hepatitis: 12 patients had serum HBeAg (group A), and 15 patients were anti-HBe positive (group B). Part of each biopsy fragment was processed for histologic and immunohistochemical studies, and a part was used for HBV-DNA analysis. Dewaxed sections from each specimen were tested with a specific monoclonal anti-HBe antibody; then a Biotin-Streptavidin kit was used as detection system. HBeAg was revealed in 10 of 12 cases of group A and in 6 of the 15 cases of group B. Pre-core region of HBV genomes, isolated from each biopsy specimen, was analyzed by direct sequencing: 10 cases of group A were found to be infected by wild-type HBV alone and 2 cases by both wild and e-minus HBV types. In group B, all the 6 cases with intrahepatic HBeAg reactivity were found to be infected by mixed viral population, whereas the 9 cases negative for such reactivity were found to be infected by e-minus HBV alone. These results show that HBeAg can be detected in formalin-fixed, paraffin-embedded liver specimens, and the method is sensitive and specific. Because the presence of HBeAg in the liver indicates a wild-type HBV infection, and the lack of detection of such antigen in the hepatocytes of anti-HBe positive subjects correlates with unmixed e-minus HBV infection, the authors conclude that this technique is a useful tool for recognizing the viral strains that infect patients with chronic type B hepatitis.

5-ASA enema versus oral sulphasalazine in maintaining remission in ulcerative colitis

This prospective trial in patients with left-sided ulcerative colitis evaluated the efficacy and acceptability of biweekly high-dose 5-aminosalicylic acid (5-ASA) enemas (4g/100ml) in maintaining a remission recently induced using daily 5-ASA enemas. Thirty-one patients were randomly assigned, 16 to 5-ASA and 15 to oral sulphasalazine (2g/day), and examined monthly. Sigmoidoscopy was performed "blind" at six months or at clinical relapse. Twelve patients on 5-ASA (75%) and nine on sulphasalazine (60%) remained in clinical and endoscopic remission throughout the study (NS), and the survival curve for 5-ASA was better at all points (NS). No patient stopped therapy due to side effects, and all those on 5-ASA chose to continue rectal maintenance therapy after the study. It was concluded that biweekly 5-ASA enemas is at least as effective as oral sulphasalazine in maintaining remission in unselected patients whose remission has been achieve using local therapy.

Polyphasic type A hepatitis: histological features

The histology of polyphasic type A hepatitis was analyzed in liver biopsy specimens of two patients. The microscopic examination showed, together with changes of acute viral hepatitis, portal plasma cell infiltration, limiting plate erosion and porto-portal bridging necrosis. These features, although sometimes described in classical HAV hepatitis, appear to be similar to those commonly observed in severe and evolving forms of acute hepatitis due to other hepatotropic viruses. Only careful serological analyses can lead to a correct diagnosis and prognosis in case of polyphasic type A hepatitis.

Life events, personality, and physical risk factors in recent-onset duodenal ulcer. A preliminary study

To clarify the interactions between stressful life events and other risk factors in the development of duodenal ulcer disease, we studied 33 patients with active ulcer, symptomatic for less than or equal to 6 months and untreated during the previous year, using the Paykel Interview for stressful life events, the Minnesota Multiphasic Personality Inventory (MMPI), and Zung's Anxiety and Depression scales. MMPIs were abnormal in 64% of the patients, and 61% showed some degree of depression. The 16 patients whose symptoms had been preceded by severe stress and more pathological MMPIs, especially on paranoia and dependency scales; were more depressed; and had used less nonsteroidal anti-inflammatory drugs than those without (p less than 0.05). They were somewhat more likely to be single, to be of low social class, and to have recently increased use of cigarettes, alcohol, or coffee (though their absolute level of alcohol consumption was low). Anxiety levels did not differ between stress and nonstress groups. Correspondence analysis yielded four clusters of patients, characterized by (a) alcohol/cigarette use, personality disorder, chronicity; (b) early onset, neurosis; (c) depression, life events; (d) late onset, psychosocial stability. The analysis changed little according to whether life events were or were not considered in cluster formation. We conclude that ulcer patients who become ill under stress from a distinct subgroup, that depressed mood and stress-related increases in use of alcohol and cigarettes may mediate between stress and ulcer formation, and that life events are a quantitatively minor factor in ulcerogenesis.

Plasmodium chabaudi and Trypanosoma cruzi infections can reverse IgG2ab chronic suppression in mice

The effects of infections with Plasmodium chabaudi or Trypanosoma cruzi on chronic CD8+ T cell dependent IgG2ab suppression were analyzed in homozygous Ighb/b adult mice. These parasites are known to induce a CD4+ T cell dependent polyclonal activation characterized in particular by a considerable increase in IgG2a expression. We report here that infection with either parasite reversed the IgG2ab suppression in 18 out of 32 mice. However, in mice treated with anti-CD4 mAb in parallel to the parasite infection, the polyclonal activation was largely reduced and the suppression of IgG2ab expression was always maintained. The parasite induced escape from suppression could result from increased helper T cell activation stimulating some of the Ig production. A weakening of the CD8+ T cell activity which is specific of IgG2ab could also contribute to the IgG2ab production. Both effects would shift the previous equilibrium which was in favour of suppression to a new balance allowing expression of the IgG2ab allotype.

Trypanosoma cruzi: predominance of IgG2a in nonspecific humoral response during experimental Chagas' disease

The kinetic and isotypic pattern of hypergammaglobulinemia has been investigated in C3H/HeJ infected with Trypanosoma cruzi. Hypergammaglobulinemia appeared 14 days postinfection, increased until Day 28 postinfection, and persisted throughout the chronic phase (greater than 60 days of infection). The main isotype secreted was IgG2a, reaching 10-fold the control level. High titers of autoantibodies were found of IgM and IgG subclasses. Isotypic characterization of antibodies against myosin, myelin, and keratin, was performed and determined to be IgG2a subclass in the chronic stage of infection. Specific responses against T. cruzi took place 2 weeks postinfection when the parasitemia was high. Interestingly, parasite-specific response was maximal after 4 weeks of infection and plateaued during the chronic phase when parasites were rare. In contrast to the humoral polyclonal response in the chronic stage, showing a preferential IgG2a pattern, the anti-T. cruzi response consisted of all the different isotypes: IgM, IgG1, IgG3, IgG2a, and IgG2b, throughout the infection. Identical patterns of parasite antigens were recognized by IgG2a and IgG2b antibodies. Few different antigens were identified by the IgG3. Some antigens were recognized by several isotypes, others by only one isotype. With regard to the existence of antigenic cross-reactivities between host and parasite, we designed absorption experiments on parasite-specific immunoadsorbent showing that specific antibodies eluted from the column failed to recognize the natural antigens. These studies suggest that nonspecific and antiparasite-specific responses may be maintained by different regulatory pathways.

Xid immunodeficiency imparts increased parasite clearance and resistance to pathology in experimental Chagas' disease

Infection of several mouse strains with Trypanosoma cruzi stimulates high levels of T and B lymphocyte activities which persist during the chronic phase and is followed by specific immunosuppression and severe autoimmune pathology. Infected BALB.Xid mice carrying an X-linked mutation and lacking CD5 B cells, display poor B cell responses to T. cruzi infection, accompanied by low levels of specific and non-specific immunoglobulins in the serum. However, these animals control parasitemia, do not show the wasting observed in BALB/c mice, and develop almost no pathology early in the chronic phase. The infection of (BALB.Xid female x BALB/c male) F1 animals shows that immunodefective males behave like Xid animals in contrast to females which respond as normal BALB/c mice. These results indicate that the Xid locus controls lymphocyte responses, parasite clearance and pathology in experimental Chagas' disease.

A CD4+ TH2 cell line isolated from mice chronically infected with Trypanosoma cruzi induces IgG2 polyclonal response in vivo

In our study we describe further characteristics of a CD4+ T cell line (G-05) isolated from lymph nodes of C3H/HeJ mice chronically infected with Trypanosoma cruzi. This T cell line secreted lymphokines such as interleukin (IL) 4 and IL 5 and could be defined as a TH2 type of helper T cells. By passive transfer into naive mice, the G-05 line was able to induce a polyclonal B cell activation in the spleen. This splenic B cell activation was quite similar to that seen in chronically T. cruzi-infected animals, where the isotypic pattern presents a large increase of IgG2a and IgG2b isotypes. Moreover, it was possible to reproduce this kind of polyclonal B cell activation in vivo, with the supernatant of G-05 T cells cultured in the presence of T. cruzi extract, accessory cells and exogenous IL 2. Analysis of this supernatant showed the presence of large amounts of IL 4, IL 5, IL 3 and IL 6 but not of interferon-gamma, and residual IL 2 activity was not significant. These results suggest that the G-05 T cells considered as TH2 cells on the basis of their lymphokine production are involved in the development of the in vivo polyclonal B cell activation in T. cruzi infection.

Anti-Ia treatment modulates specific and polyclonal antibody responses in Trypanosoma cruzi-infected mice

Experimental Chagas' disease--infection of mice with the protozoan parasite Trypanosoma cruzi--has been shown to increase the number of Ia-bearing cells in the spleen and the lymph nodes. The majority of these Ia-positive cells were Ig+ and included in the large cell fraction of lymphoid organs from T. cruzi-infected animals indicating that they were activated B cells. These data are consistent with the polyclonal B-cell activation occurring during acute and chronic T. cruzi infection. The levels of secreted natural antibodies, of both IgM and IgG isotypes, were significantly increased in the sera of the infected animals. The present communication demonstrates that in vivo anti-Ia treatment of C3H/HeJ mice infected with the CL strain of T. cruzi suppressed the polyclonal B-cell activation, affecting all the isotypes studied, including IgM, IgG2a and IgG2b, whose levels are predominantly increased during T. cruzi infection. In contrast to the decreased secretion of IgG autoantibodies, the levels of IgM autoantibodies were much less affected. The anti-Ia treatment totally abolished the specific anti-parasite response despite the fact that a pool of Ia-Ig positive cells remained after treatment.

Genetics and strain distribution of concanavalin A-reactive Ly-2-, L3T4- peripheral precursors of autoreactive T cells

Cytotoxic treatment of BALB/c cells from different peripheral lymphoid tissues by a cocktail of monoclonal antibodies against Thy-1, Ly-1, L3T4 and Ly-2 differentiation markers (anti-T cocktail) plus complement eliminates all mature T lymphocytes. Yet a population of dull Thy-1+, Ly-1-, L3T4-, Ly-2-, corresponding to about 1% of the initial population, can be detected by flow cytometry which proliferate under concanavalin A stimulation. These anti-T killing-resistant cells (TKR) were previously shown to be capable of differentiating in culture into class II-restricted autoreactive T helper cells. We demonstrate here that such cells can be detected in mice of BALB/c and DBA/2 genetic background but are absent in C57BL/6 and B10 animals. The presence of TKR cells is dominant in (BALB/c x C57BL/6)F1 hybrids and genetically controlled by two genes which are neither H-2 nor Igh linked. TKR cells are also detected in young NZB mice but disappear with the development of the systemic autoimmune disease in old animals. Thy-1+, L3T4-, Ly-2- cells from MRL lpr/lpr mice also respond to concanavalin A but are removed by the anti-T treatment. Altogether, arguments are presented suggesting that TKR cells represent a particular subset of double-negative peripheral T cells which may correspond to autoreactive T cell recursors that would escape the thymic selection. We postulate that these cells are present in all mouse strains but their susceptibility to killing by anti-Thy-1 antibodies differs depending on background genes.

Origin of autoreactive T helper cells. I. Characterization of Thy-1+, Lyt-, L3T4- precursors in the spleen of normal mice

A new population of dull Thy-1+, Ly-1-, Lyt-2-, L3T4- PNA- cells, resistant to a double cytotoxic treatment by monoclonal antibodies to these T cell markers plus complement, has been isolated from the spleen of normal adult BALB/c and DBA/2 mice (Tkr cells). These cells exhibit no spontaneous autoreactivity or alloreactivity but can be activated with concanavalin A (Con A). Once activated, they differentiate into bright Thy-1+, Ly-1+, Lyt-2-, L3T4+ PNA- T lymphocytes. Con A-activated Tkr cells also strongly proliferate in the presence of allogeneic or syngeneic dendritic cells in secondary cultures. Moreover, contrary to other Con A-stimulated T cell populations, they induce B lymphocytes to proliferate and to differentiate into Ig-secreting cells at a very high level. Con A-activated Tkr cells are therefore very potent polyclonal B cell activators. Restimulated of Tkr cells by syngeneic dendritic cells can be inhibited by anti-L3T4 or anti-class II monoclonal antibodies. The results suggest that Tkr cells are the precursors of class II-specific autoreactive T helper cells. Tkr cells are absent in the spleen of B6 animals. This indicates that their expression might be genetically controlled. It also suggests that Tkr cells may not be the unique splenic precursors of autoreactive T cells. Con A activation of Tkr cells in Click's medium is 2-mercaptoethanol dependent and highly sensitive to pCO2, like the response of thymocytes. Tkr cells are also absent in the spleen of nude mice. We conclude that Tkr cells represent splenic precursors of autoreactive T helper cells equivalent to Thy-1+, Ly-2-, L3T4- PNA- cortical thymocytes.

Origin of autoreactive T helper cells. I. Characterization of Thy-1+, Lyt-, L3T4- precursors in the spleen of normal mice

A new population of dull Thy-1+, Ly-1-, Lyt-2-, L3T4- PNA- cells, resistant to a double cytotoxic treatment by monoclonal antibodies to these T cell markers plus complement, has been isolated from the spleen of normal adult BALB/c and DBA/2 mice (Tkr cells). These cells exhibit no spontaneous autoreactivity or alloreactivity but can be activated with concanavalin A (Con A). Once activated, they differentiate into bright Thy-1+, Ly-1+, Lyt-2-, L3T4+ PNA- T lymphocytes. Con A-activated Tkr cells also strongly proliferate in the presence of allogeneic or syngeneic dendritic cells in secondary cultures. Moreover, contrary to other Con A-stimulated T cell populations, they induce B lymphocytes to proliferate and to differentiate into Ig-secreting cells at a very high level. Con A-activated Tkr cells are therefore very potent polyclonal B cell activators. Restimulated of Tkr cells by syngeneic dendritic cells can be inhibited by anti-L3T4 or anti-class II monoclonal antibodies. The results suggest that Tkr cells are the precursors of class II-specific autoreactive T helper cells. Tkr cells are absent in the spleen of B6 animals. This indicates that their expression might be genetically controlled. It also suggests that Tkr cells may not be the unique splenic precursors of autoreactive T cells. Con A activation of Tkr cells in Click's medium is 2-mercaptoethanol dependent and highly sensitive to pCO2, like the response of thymocytes. Tkr cells are also absent in the spleen of nude mice. We conclude that Tkr cells represent splenic precursors of autoreactive T helper cells equivalent to Thy-1+, Ly-2-, L3T4- PNA- cortical thymocytes.

Gastric acid and pancreatic polypeptide responses to modified sham feeding: indication of an increased basal vagal tone in a subgroup of duodenal ulcer patients

The effect of sham feeding upon gastric acid secretion and pancreatic polypeptide release was investigated in 28 patients with duodenal ulcer in order to evaluate whether high basal vagal activity is the cause of basal acid hypersecretion in patients with duodenal ulcer and basal secretion higher than 30% of their peak acid output. The patients were divided into two groups based on the ratio of basal/pentagastrin stimulated peak acid output (BAO/PAO) was higher or lower than 0.30: group A n = 19 (BAO/PAO less than or equal to 0.30) and group B n = 9 (BAO/PAO greater than 0.30). Gastric acid response to sham feeding (SAO) was significantly higher than basal level in group A (SAO: 11.4 mEq/h (2.5-20.1) vs BAO: 5.2 mEq/h (0.8-22.9), p less than 0.01, median (range)) while in group B the acid secretion did not increase with sham feeding (SAO: 9.6 mEq/h (4.5-13.6) vs BAO: 8.8 mEq/h (6.3-13.8) ns, median (range)). A negative correlation (r= -0.6118226, p less than 0.01) was found between acid increase expressed as basal subtracted sham feeding response (SAO-BAO) and BAO/PAO ratio of the entire group of duodenal ulcer patients (n = 28) suggesting that the greater is basal acid secretory capacity the smaller is acid increase in response to residual vagal activation. Pancreatic polypeptide response to sham feeding was higher in group A than in group B but no correlation (r = 0.20, n = 28) nor individual covariation was found between acid and pancreatic polypeptide secretions during vagal stimulation. sham feeding did not change serum gastrin. It is concluded that an increased vagal stimulation seems to be the cause of basal hypersecretion in a subgroup of patients with duodenal ulcer. The lact of correlation between the pancreatic polypeptide and acid responses to vagal stimulation interferes with the reliability of pancreatic polypeptide as indicator of vagal tone on gastric parietal cells.