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Biomedical subjects

P Pozzilli

Publications and source records attributed to P Pozzilli.

At least 199 records · Page 11Linked to original sources
PubMed1986

White cells transfusion in recent onset type 1 diabetes.

Two HLA-identical brothers developed Type 1 diabetes simultaneously. In the light of present knowledge of the pathogenesis of Type 1 diabetes, immunosuppression was adopted in one brother by means of white cell transfusion from the father. The other brother acted as a control. This immunosuppressive approach has been shown to be effective in kidney transplantation and, as far as Type 1 diabetes is concerned, in the BB Wistar rat. An immunological and metabolic follow-up study of 1 yr only revealed slight differences between the 2 brothers (who are both on insulin) but the pattern of lymphocyte activation appeared to become normalized earlier in the transfused brother.

Adolescent↗
PubMed1985

Sera from diabetic pregnant women contain reduced titres of inhibiting factors on killer cell activity.

The presence of Fc-receptor-blocking factors in the sera of normal and insulin-dependent diabetic pregnant women was investigated by means of an antibody-dependent cell-mediated cytotoxicity assay. Sera from normal pregnant women induced a significant depression of antibody dependent cell-mediated cytotoxicity when compared with sera from normal and diabetic non-pregnant women (p less than 0.0001; p less than 0.002, respectively). The effect of sera from diabetic pregnant women, however, was not different from that observed with sera from normal and diabetic non-pregnant women. Thus, we confirm the presence of Fc-receptor-blocking factors in the sera of normal pregnant women. The higher cytotoxicity levels measured in the presence of sera from pregnant women with insulin-dependent diabetes suggests that the titres of such factors are reduced in this condition.

Adolescent↗
PubMed1985

Study of the diurnal variation of human lymphocyte subsets.

The diurnal variation of peripheral white cells and in particular of different lymphocyte subsets has been investigated in 11 normal subjects. Monoclonal antibodies (Mab) phenotyping total T lymphocytes (UCHT1), cytotoxic/suppressor (UCHT4), helper T cells (Leu 3a), B lymphocytes (231) and K/NK cells (H25) have been used. In addition to the traditional parametric statistics, the chronobiological approach of cosinor was adopted in order to inferentially obtain the waveform covering the 24-hr period. Cosinor analysis validated the existence of a significant rhythm for leucocytes (p = 0.04, lymphocytes (p = 0.03), and Leu 3a positive cells (p = 0.04). The best fitting period was equal to 28 hr. No circadian rhythm was documented for lymphocyte subsets positive for Mab UCHT4, 231, H25, by testing the variability with a frequency ranging from 1 cycle every 12hr to 1 cycle every 28 hr. By the non-inferential analysis of temporal curves, a significant peak of Leu 3a positive cells at 20.00 hr (p less than 0.001) was observed. The acrophase has been recorded by cosinor analysis at 20.36 hr. We conclude that the circadian variability of Leu 3a positive cell profile must be taken into account when the helper/suppressor ratio is calculated. The time-dependence of this lymphocyte subpopulation suggests that when therapy with corticosteroids is considered in autoimmunity, it should be planned by keeping the peak of Leu 3a positive cells as a marker time.

Adult↗
PubMed1985

A cell surface monoclonal antibody (H366) helps to discriminate human cytotoxic from suppressor T cells.

A study has been undertaken to differentiate T cytotoxic (Tc) and T suppressor (Ts) cell subsets using a monoclonal antibody termed H366 (mouse IgG2b) previously reported to phenotype natural killer and killer (NK/K) cells. Mononuclear cell suspensions from 14 normal subjects were depleted of H366+ cells by means of complement dependent cytotoxicity and the remaining cells were phenotyped with CD8 and CD4 monoclonal antibodies. The effects of depletion with H366 plus complement (C1) on the induction and activity of suppressor and cytotoxic T cells was also examined. The results indicate that H366 antibody recognizes in addition to NK/K cells, a population of Tc but not Ts or helper cells. Therefore, H366 antibody can be useful for obtaining Ts enriched lymphocyte subpopulations and this property may also be used for the enumeration of suppressor cells in the peripheral blood in disease states.

Antibodies, Monoclonal↗
PubMed1985

T cell early activation antigens expressed by peripheral lymphocytes in Crohn's disease.

We studied the expression of early activation antigens (4F2, transferrin receptor, IL-2 receptor) on peripheral lymphocytes (PBL) of patients with Crohn's Disease. We have found that the proportion of PBL expressing these antigens was significantly higher in patients than in controls. The expression of the 4F2 antigen was more pronounced than that of other activation antigens directly involved in promoting cell growth (e.g. transferrin receptor, IL-2 receptor). These results indicate that CD patients have an increased number of T cells in a very early phase of activation.

Adult↗
PubMed1985

Activated T cells in Graves' disease before treatment.

The aim of this study was the definition of abnormalities occurring within T-cell subsets of thyrotoxic Graves' patients before treatment. Special emphasis was placed on the enumeration of activated T cells using a number of new monoclonal antibodies. Lymphocytes from 22 Graves' disease patients were examined. The total number, the percentage of 'helper/inducer' and 'suppressor/cytotoxic' positive cells were evaluated using the antibodies T3, T4 and UCHT4, whereas the cells with killer activity were defined by H25. Activated T cells were detected using the antibodies DA6.231, DA6.164, and L243 which bind different epitopes of the beta chains of class II surface antigens and 4F2, which binds a 120,000 molecular weight glycoprotein. The results show no significant change in the total T, helper or suppressor cell phenotype, but an increase in the killer cell percentage was noted. Of those patients tested, 19 of 22 showed an increase in activated T cells, 18 of 22 patients showed a significant increase of T cells bearing class II antigens, 11 of 22 showed an increase of T cells staining with another activated T cell antibody, 4F2. The anti-DR antibodies expressed different binding characteristics, the most striking difference being seen between the antibodies DA6.231 and L243. The results of this study suggest an heterogeneity of the immune response, or differences in activation stage in patients with Graves' disease before therapeutic intervention. An important role for these cells in the pathogenesis of this disorder can be inferred.

Adolescent↗
PubMed1985

Effect of unlabeled indium oxine and indium tropolone on the function of isolated human lymphocytes.

The purpose of this study was to compare the effect of indium oxine and indium-tropolone complexes (nonradiolabeled) on the function of isolated human lymphocytes. peripheral lymphocytes were obtained from 15 normal volunteers and incubated with indium oxine or indium tropolone according to the standard techniques currently used when cells are radiolabeled for subsequent in vivo studies. The phytohemagglutinin-induced (PHA) lymphocyte transformation and a more specific lymphocyte functional test (the mixed lymphocyte reaction) were performed following incubation with the indium complexes. The results indicate that PHA transformation is not affected by either indium oxine or indium tropolone, whereas both chelates reduced the mixed lymphocyte reaction. This suggests that these substances have a selective toxic effect only on a functionally distinct lymphocyte subset (i.e., the cytotoxic T cells) and indicates that there is no significant difference between the two indium chelates in terms of their effect on lymphocyte function.

Adult↗
PubMed1985

Inhibition of the receptor for interleukin-2 induced by carbimazole: relevance for the therapy of autoimmune thyroid disease.

Evidence has been accumulated that the anti-thyroid drugs used in the treatment of Graves' disease may have immunosuppressive properties but the exact mechanism of action is still unclear. In the present study, we have investigated the in vitro effect of carbimazole (CBZ) on the expression of lymphocyte differentiation antigens and on suppressor cell activity. The incorporation of radiolabelled methimazole (35S-MMI, the active metabolite of CBZ) by resting and mitogen stimulated lymphocytes was also investigated. CBZ at concentrations of 60 microM significantly inhibited the expression of the receptor for interleukin-2 (as defined by the anti-TAC monoclonal antibody [MoAb]) by lymphocytes stimulated with phytohaemagglutinin. The expression of an early activation antigen (as characterized by the 4F2 MoAb) was not affected. Twenty-four hour pre-incubation of cells with different concentrations of CBZ or medium alone did not change the lymphocyte response to mitogenic stimulation, thus suggesting no effect of the compound on suppressor cell function. Finally, there were no significant differences in the uptake of 35S-MMI between resting and stimulated lymphocytes. These data suggest that the immunosuppressive effect of CBZ may be due to its effect of reducing the expression of the receptor for interleukin-2 on lymphocytes undergoing full activation. This property of CBZ could be of relevance in the therapy of autoimmune thyroid diseases (not only Graves' disease) which are characterised by the presence of activated T cells in the thyroid and in circulation.

Adult↗
PubMed1985

Homing and circulation of indium-111-labelled leucocytes. A post-mortem study.

The history of a patient with a suspected ischemic brain infarct undergoing an indium-111-tropolone white cell labelled test is reported. The patient, who died 12 h after injection of the labelled cells, suffered of a brain haemorrhage. The post-mortem examination has allowed for the first time the measurement of radioactivity in different organs following the injection of indium-111-labelled leucocytes. High radioactivity was found only in tissues affected by inflammatory processes and in the lymphonodes draining the corresponding areas. This report clearly indicates the importance of this method for the study of white cell localization and circulation to the sites of infections.

Cerebral Hemorrhage↗
PubMed1985

In vitro inhibition of insulin release mediated by sera with complement-fixing islet cell antibodies belonging to normal first degree relatives of patients with type 1 diabetes.

Islet cell antibodies (ICA) are present in the sera of most patients with Type 1 diabetes at diagnosis and in some of their genetically susceptible, but otherwise normal, first degree relatives. In this study we have investigated basal and stimulated insulin release by mouse islets following preincubation with human sera (with or without the addition of guinea pig complement) belonging to: 15 normal first degree relatives of diabetic probands; 7 patients with Type 1 diabetes; 7 control subjects with no history of diabetes. All sera had been previously screened for conventional (IgG), complement fixing (CF) and surface (S) ICA. Basal insulin release was not altered by any of the sera. The response to stimulus after incubation with ICA negative and IgG-ICA positive (but CF-ICA negative) sera was similar whether complement was present or not. Stimulated insulin release was significantly inhibited by complement and sera from 2 relatives and 3 diabetic patients. These sera were CF-ICA positive, the sera of the 2 relatives being also ICSA positive. One relative developed Type 1 diabetes 14 months later. This study demonstrates for the first time that sera containing CF-ICA and belonging to individuals susceptible to Type 1 diabetes, can impair insulin release in vitro. It is therefore likely that antibody-dependent, complement-mediated mechanisms are involved in the pathogenesis of Type 1 diabetes.

Adult↗
PubMed1984

Prospective study of lymphocyte subsets in subjects genetically susceptible to type 1 (insulin-dependent) diabetes.

A prospective study of lymphocyte subsets has been carried out for 18 months in 58 healthy first-degree relatives of Type 1 (insulin-dependent) probands. Subjects selected for presence or absence of islet cell antibodies included 10 with complement-fixing islet cell antibodies, 10 with conventional islet cell antibodies and 38 without islet cell antibodies. Immunoregulatory and effector lymphocytes subsets, and in particular activated T-cells, were investigated using a panel of monoclonal antibodies. The results showed no significant changes in total T, helper, suppressor/cytotoxic cell or K/NK cells. Activated T-cells were observed at least once in 22 subjects using the 4F2 monoclonal antibody and in 11 using the Tac antibody. Seven subjects had 4F2-positive cells on repeated occasions and one twice showed Tac-positive cells. Fluctuations and/or loss of islet cell antibodies were observed during follow-up. There was no correlation between presence of activated T-cells and either islet cell antibody status of HLA haplotype sharing with the diabetic proband. On the other hand, a significant correlation was observed between HLA-DR3 positivity of subjects and the occurrence of activated T-cells (both 4F2-positive and Tac-positive). We conclude that subjects with HLA-DR3 may be especially prone to T-cell activation. As none of the 'high risk' individuals developed diabetes in the course of follow-up, the relevance of these observations in the pathogenesis of Type 1 diabetes needs more prolonged investigation.

Antibodies↗
PubMed1984

Lymphocyte subsets and immune complexes in long-standing diabetic patients: relation with the presence of microangiopathy.

Subsets of peripheral T lymphocytes by monoclonal antibodies and circulating immune complexes by two different methods were evaluated in 36 long-standing diabetic patients, 19 Type 1 (insulin dependent) and 17 Type 2 (non-insulin dependent). In all patients the presence of microangiopathy was assessed by retinal fluoroangiography, albuminuria and creatinine clearance. In patients with Type 1 diabetes a significant decrease of total T and of T cells with helper phenotype (T4), together with an increase of T cells with suppressor/cytotoxic phenotype (T8), were observed. No significant modifications in the percentage of T lymphocyte subsets were detected in patients with Type 2 diabetes. Immune complexes were found to be significantly increased in Type 1 compared with Type 2 diabetic patients. Patients with very high levels of T8+ cells did not have detectable immune complexes and had no evidence of microangiopathy. By contrast, patients with normal levels of these cells were found to have raised immune complexes and showed retinopathy of varying degree. The results of this study indicate that: (1) a relationship exists between cells with T8 phenotype, some immune complexes and the presence of microangiopathy; (2) the decrease of T4+ cells in Type 1 diabetics with long duration of disease may be responsible for the known susceptibility to infections in these patients.

Adolescent↗
PubMed1984

Cell-mediated immunity in the aetiopathogenesis of insulin-dependent (type I) diabetes mellitus.

We have investigated lymphocyte subpopulation levels with monoclonal antibodies in newly diagnosed insulin-dependent (type I) diabetics and in unaffected siblings of type I diabetic probands with islet cell antibodies. Our data show that in newly diagnosed diabetics there is 1) a decrease in T cells with suppressor phenotype, 2) an increase of T cells with cytotoxic phenotype and 3) the presence of "activated" T cells. The latter have also been found in some unaffected siblings with islet cell antibodies. These results suggest that cellular immune alterations are present, not only at diagnosis, but also in normal but "susceptible" individuals. "Activated" T cells could be a "disease" marker, but their better definition in terms of specificity should be established.

Antibodies, Monoclonal↗