Granulocyte and natural killer activity in the elderly

The deterioration of the immune system in ageing, 'immunosenescence', is thought to contribute to increased morbidity and mortality from infections and possibly autoimmune diseases and cancer. The most profound changes involve effector and immunoregulatory T-cell functions. Immunosenescence appears also to be related to changes in non specific immunity as well. In the present study we have assessed superoxide production, chemotaxis and the expression of the apoptosis-related molecule APO1/Fas (CD95) on neutrophils (PMN) from young and old subjects. Furthermore, we have measured the basal natural killer (NK) activity of young and elderly subjects and we have compared the number of CD16+ cells found in these two groups. We observed a significant decrease age-related both of formation of O2- and chemotaxis whereas no significant correlation between age and the expression of CD95 on granulocyte membrane was demonstrated, suggesting that an increase age-related of CD95-linked apoptosis of PMN should be not an important determinant in the decreased PMN function. We also observed a significant correlation between age and NK activity. The decreased NK cell function was not due to a decreased number of NK cells in effector cell preparations since the number of CD16+ cells was significantly increased in old subjects. In conclusion, our results show that in the elderly there is also a deficit of the aspecific immunity that might play a role in the pathogenic mechanisms of the immunosenescence.

T cells and aging (update february 1999)

Deterioration of the immune system with aging ("immunosenescence") is believed to contribute to morbidity and mortality in man due to the greater incidence of infection, as well as possibly autoimmune phenomena and cancer in the aged. Dysregulation of T cell function is thought to play a critical part in these processes. Factors contributing to T cell immunosenescence may include a) stem cell defects, b) thymus involution, c) defects in antigen presenting cells (APC), d) aging of resting immune cells, e) disrupted activation pathways in immune cells, f) replicative senescence of clonally expanding cells. This review aims to consider the current state of knowledge on the scientific basis for and potential clinical relevance of those factors in immunosenescence.

Serum levels of soluble CD23 in patients with asthma or rhinitis monosensitive to Parietaria. Its relation to total serum IgE levels and eosinophil cationic protein during and out of the pollen season

The diagnostic value for allergies of the low affinity IgE receptor and its soluble circulating fragment (sCD23) remains unclear. In particular, little is know about seasonal influences on serum sCD23 levels in subjects with pollen allergy. In the present study, to gain insight into pathophysiological role of sCD23, we have analyzed, in blood from patients allergic to Parietaria sCD23, IgE, and eosinophil cationic protein (ECP) serum levels. IgE were assessed as atopy markers and ECP as an inflammation marker. Patients were studied during and out of pollen season, and results were compared to those obtained in nonallergic subjects. The study population included 42 nonsmoking outpatients, living in Palermo (Sicily, Italy) or in other west Sicilian towns, with a clinical diagnosis of seasonal asthma or rhinitis and monopositive skin test to Parietaria pollen. The group of asthmatic subjects consisted of 25 patients who had one or more of the usual asthma symptoms (wheezing, dyspnea, and cough) only during the pollen season. The group of rhinitis patients consisted of 17 patients, who, during pollen season, had the nasal symptoms (nasal blockage, sneezing, nasal itching, and rhinorrhoea) but no signs of asthma. As a control group, we studied 10 nonatopic subjects from laboratory staff. They had no history of seasonal or perennial rhinitis, asthma, or urticaria and had negative skin tests to a panel of allergens. Soluble CD23, IgE, and ECP were assessed in blood during and out of pollen season. Total serum IgE levels were clearly higher in atopic patients, as classically established. Concerning sCD23 serum levels, a similar pattern of results was obtained. Accordingly, significant correlations were shown between the levels of sCD23 and IgE in all groups of patients. A completely different pattern was observed by analyzing serum ECP levels because ECP levels were significantly increased only in asthmatic patients during pollen season. Accordingly, no significant correlations were observed between the levels of sCD23 and those of ECP. Identifying immune factors associated with the development of atopy can enhance our understanding of the in vivo mechanisms involved and may have utility in paradigms designed to prevent diseases. As demonstrated by the close correlation with total serum IgE values and the lack of correlation with serum ECP values, serum levels of sCD23 appear to be an additional marker for the diagnosis of atopy but not for the follow-up of allergic diseases.

Interleukin-5 production by mononuclear cells from aged individuals: implication for autoimmunity

It is well known that in the elderly a deterioration of immune functions may occur. Particularly, stimulation of T cells from aged individuals leads to different kind and/or size of responses if compared with the responses obtained from T cells from young individuals. At the same time, an increase in prevalence of autoantibodies occurs in elderly. The altered production of certain cytokines might explain this paradox of decreased responsiveness to foreign antigens in the face of an increased response to self-antigens. We and others have suggested that this kind of immune response might depend on an age-associated impairment of Th-1 type function that selectively affects production of cytokines involved in the control of cellular responses. In contrast, Th-2 type function is seemingly not affected in elderly, as suggested by normal in vitro production of cytokines involved in humoral responses. To strengthen this hypothesis, in this study we have analysed the influence of age on the ability of mitogen-stimulated cultures of peripheral blood mononuclear cells from human beings to produce another Th-2 type cytokine, i.e. interleukin-5 (IL-5). IL-5 content of both 24- and 48-h stimulated cultures from old individuals was greater than that of young ones, although this difference attained significance only at 48 h. We suggest that the decreased production of Th-1 type cytokines in the presence of a normal or even increased production of Th-2 type cytokines might account for the pattern of immune response which may be observed in elderly, i.e. a normal or increased humoral response, including an autoimmune one, in the face of a low cell mediated immune response.

A computer program to compare sequence fingerprints of homologous proteins for the rapid assessment of their primary structure differences

We have developed a computer program for the rapid assessment of the primary structure differences between a protein of unknown sequence and a homologous known protein. Both proteins are reduced, alkylated, and digested with the same hydrolytic agent. The unfractionated peptide mixtures are submitted to automatic sequence analysis. Based on the knowledge of the reference sequence, the program utilizes the analysis data to identify all the potential peptides present in the two mixtures, determining their primary structure, homology degree, and molecular weight calculated both as integer MH+ and average mass variables. These fingerprints allow the user to easily identify the structural differences between the two proteins and clarify possible doubts by a mass spectrometric analysis of the two mixtures. In order to verify the utility of the program, we provide an application example using the already reported data of two homologous proteins.

Bronchial reactivity and intracellular magnesium: a possible mechanism for the bronchodilating effects of magnesium in asthma

1. Increased bronchial smooth muscle contractility with consequent bronchial hyperreactivity are characteristic physiopathological events of asthma. Since magnesium intervenes in calcium transport mechanisms and intracellular phosphorylation reactions, it constitutes an important determinant of the contraction/relaxation state of bronchial smooth muscle. In the present study we investigated the relationship between bronchial reactivity, assessed by methacholine-provocation test, and magnesium concentrations both at extracellular and intracellular levels measured by spectrophotometry. Twenty-two patients with mild-to-moderate asthma and 38 non-asthmatic subjects with allergic rhinitis (24 allergic to Parietaria pollen and 14 allergic to Grass pollen) were recruited to the study. Exclusion criteria included renal failure, hepatic diseases, heart failure and arterial hypertension. 2. The salient finding of our study is that there is a strong positive correlation between bronchial reactivity and the level of intracellular magnesium (r=0.72, P<0.0001), both when the groups are analysed separately or together. Intracellular magnesium concentrations in the group of patients with asthma were significantly lower (1.8+/-0. 01 mmol/l; n=22) when compared with levels in rhinitis subjects allergic to Parietaria (1.9+/-0.01 mmol/l; n=24, P<0.05), and with levels in rhinitis subjects allergic to Grass pollen (2.0+/-0.03 mmol/l; n=14, P<0.05). Serum levels of the ion were similar in all groups. 3. We conclude that the level of intracellular magnesium may be an important determinant of bronchial hyperreactivity, as supported by the significant positive correlation between these two parameters in allergic patients with known bronchial hyperresponsiveness. This finding, in addition to reports of the bronchodilating effects of magnesium administration in patients with asthma, confirms the proposed role of this ion in the pathogenesis and treatment of asthma.

Hypothesis: interleukin-5 production impairment can be a key point in the pathogenesis of the MHC-linked selective IgA deficiency

Selective IgA deficiency (IgA-D) is associated with the expression of some human leukocyte antigens (HLA) haplotypes and Major Hystocompatibility Complex (MHC) gene products have been suggested to be involved in the regulation of IgA synthesis. Recently, we have obtained evidences indicating that MHC influences the production of IgA and interleukin-5 (IL-5) both in humans and in mice. Lymphnode cells from pychril chloride (PC1) immunised BALB/c mice (bearing the H-2d haplotype) fail to produce IL-5 when stimulated in vitro with PC1 and this correlates with low antigen specific IgA production in vivo. In contrast using congenic BALB/k mice (bearing the H-2k haplotype) an high production both of IL-5 and of PC1-specific IgA is observed. Moreover, in vivo or in vitro administration of IL-5 to BALB/c mice was able to increase the production of antigen specific IgA. Similar evidences have been obtained by evaluation of the HLA influence on circulating immunoglobulin levels and interleukin production in normal HLA typed subjects. In fact HLA-B8, DR3 positive subjects show reduced level of serum IgA and their peripheral blood mononuclear cells stimulated with mitogen produce significantly reduced amounts of IL-5, IL-12, IL-2 and Interferon-gamma. We hypothesise that HLA-B8, DR3 associated IgA deficiency, known to be asymptomatic, can be due to a lack of subsequent signals, in particular of IL-5, involved in the late regulation of B cell differentiation. Preliminary evidences demonstrating that low amounts of human recombinant IL-5 are able to reconstitute IgA production by cells from HLA-B8, DR3 IgA-D subjects, seem to confirm this hypothesis.

Interleukin-12 release by mitogen-stimulated mononuclear cells in the elderly

Defects involving cellular expression of activation molecules, cell mediated immune response and natural killer (NK) activity are commonly observed in the elderly. Herein, data are reported on the evaluation of IL-12 production by old subjects. IL-12 is, actually, considered the key molecule for the induction of a T helper 1 (Th1) -type and NK response. IL-12 production from old subjects peripheral blood mononuclear cells (PBMNC) was evaluated using T-independent (bacterial lipopolysaccharide, LPS) or -dependent (phytoemagglutinin, PHA; immobilized anti-CD3 monoclonal antibodies, anti-CD3) mitogens. The IL-12 production after LPS stimulation was not reduced in cultures from old subjects when compared to that from young ones. On the contrary, IL-12 production by PHA or anti-CD3 stimulated PBMNC from old subjects was decreased. Furthermore, we have demonstrated a reduced CD40 and CD40 ligand (CD40L) expression on PBMNC from old subjects. This finding fits very well with the reduced cytokine production observed in the T-dependent stimulation systems, being the CD40-CD40L interaction mandatory for an efficient IL-12 production. All together, these results seem to suggest that defects in cell expression of activation molecules can affect the IL-12 secretion and in consequence other Th1-type cytokines.

Apoptosis and ageing

Stimulation of T cells from aged individuals leads to different kinds and/or size of responses if compared with the responses of T cells obtained from young individuals. In fact elderly is associated with a progressive decline of immune response besides an increasing incidence of autoimmune phenomena. These differences might be the result of modified cellular mechanisms controlling the immune system in the course of ageing. The apoptotic deletion of activated T cells has been proposed as the key mechanism to maintain T cell homeostasis, and in this respect CD95 (Fas antigen) seems to play a major role in this course of events. In this study we show that just collected lymphocytes from old subjects displayed an increased expression of the apoptosis molecule CD95. The expression of CD95 and the spontaneous apoptosis showed the same trend. In fact the percentage of apoptotic cells in blood collected from old subjects was enhanced too. The lymphocyte subpopulation analysis by flow cytometry did not show significant changes in T subset percentages between old and young subjects. Moreover mononuclear cells obtained from aged individuals underwent apoptosis in culture in response to a single stimulation with mitogen or anti-CD3, more than mononuclear cells from young controls. To gain insight into mechanisms of this increased apoptosis, experiments were performed to evaluate the behaviors of lymphocytes from old and young donors in respect of interleukin-2 (IL-2) rescue from apoptosis. Results show that IL-2 rescued only a little fraction of cells of old donors from apoptosis when activated by anti-CD3 and that this effect was not related to a different expression of CD95. Thus, during the course of ageing the different regulation of T cell homeostasis might be also explained by the modified proneness of lymphocytes to undergo apoptosis. The contemporaneous demonstration of a reduced Ca2+ influx in lymphoid cells of these subjects allows to suppose that multiple defects play a role in the pathogenesis of immunosenescence.

Laccase from the white-rot fungus Trametes trogii

The white-rot fungus Trametes trogii excretes a main laccase showing a molecular mass of 70 kDa, acidic isoelectric point and N-terminal sequence homologous to that of several phenol oxidases. The purified enzyme oxidizes a number of phenolic and non-phenolic compounds; recalcitrant molecules may be converted into substrates by introducing, in the correct position, o- or p-orienting ring-activating groups.

Modification of cytokine patterns in subjects bearing the HLA-B8,DR3 phenotype: implications for autoimmunity

The factors influencing the pathogenesis of autoimmune disease are not fully known, but the host genotype undoubtedly plays a role in determining the outcome of these diseases. The role of the host's major histocompatibility complex (MHC) genotype in the regulation of susceptibility to autoimmune diseases has been extensively studied in different populations, and certain HLA (the human MHC) alleles and haplotypes have been reported to be associated with several autoimmune diseases. In particular, the association with genes from the HLA-B8,DR3 haplotype has been reported by different research groups. This haplotype is associated in all Caucasian populations with a wide variety of diseases with autoimmune features, and in healthy subjects it is associated with a number of immune system dysfunctions. Mainly, peripheral blood mononuclear cells from HLA-B8,DR3-positive and -negative individuals differ in their ability to produce interleukin (IL)-2, IL-5, IL-12 and interferon-gamma upon stimulation with the mitogen phytohaemoagglutinin (PHA), while producing similar amounts of IL4, IL-6 and IL-10. Furthermore, in HLA-B8,DR3-positive subjects tumor necrosis factor alpha secretion is increased both with and without PHA stimulation. Accurate control of the functional repertoire of an immune response is a critical parameter in the response to infections as well as in immunopathology. MHC control of the class of the immune response at the level of cytokine production is a sophisticated way in which this occurs. This control might be involved in adaptive immune responses to infections as well as in immunopathology.

Allergic rhinitis to grass pollen: measurement of inflammatory mediators of mast cell and eosinophils in native nasal fluid lavage and in serum out of and during pollen season

BACKGROUND

In allergic rhinitis, mast cells, activated by cross-linking of allergen to mast cell-bound specific IgE, release both vasoactive mediators related to the early nasal symptoms and chemotactic mediators that attract inflammatory cells, such as eosinophils, related to the late-phase response.

OBJECTIVE

We have analyzed, during and out of pollen season, in blood and nasal fluid from patients allergic to grass pollen, histamine and tryptase to monitor the early phase markers and eosinophil and eosinophil cationic protein (ECP) to monitor the late phase.

METHODS

Twenty patients were enrolled in the study. As a control, we studied 10 nonatopic subjects. Mediators and eosinophils were assessed in blood and nasal fluid. Histamine was tested only in nasal fluid.

RESULTS

During pollen season, tryptase but not histamine increased in nasal fluids from patients (2.96 vs 0.22 U/ml, p = 0.001) and correlated with symptom scores (r(s) = 0.63, p = 0.003). Tryptase was not detected in serum. Eosinophils increased in nasal cytology (17.0% vs 2.0%, p = 0.001) and in the blood (265 vs 12.7 x 10(6) L, p = 0.001) from patients, but they did not correlate with symptom scores. ECP increased only in the nasal lavage (1633 vs 1.30 ng/ml, p = 0.001) and correlated with symptom scores (r(s) = 0.53, p = 0.016).

CONCLUSIONS

Both ECP and tryptase increase in nasal secretion in natural disease. Therefore the measurement of tryptase and ECP levels in nasal fluid might be a useful clinical test for monitoring disease activity and the effects of therapeutic agents.

Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells

The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of hemocytes with the antioxidant enzymes, superoxide dismutase and catalase rule out oxy radicals produced by the melanogenic process as responsible of erythrolysis. Such a result suggests that quinone compounds derived from the melanogenic pathway might be the cytotoxic molecules. The PO-dependent anti-RE activity was also shown in a plaque forming assay in which "morula cells", containing polyphenols and PO, were identified as cytotoxic.

Non-specific airway hyperresponsiveness in mono-sensitive Sicilian patients with allergic rhinitis. Its relationship to total serum IgE levels and blood eosinophils during and out of the pollen season

BACKGROUND

Initial attempts to evaluate the association between allergic rhinitis and non-specific bronchial responsiveness has produced conflicting results. In fact, some studies showed a strong correlation and other failed to find an association. However, little is known about the effect of natural specific allergen exposure on the bronchial reactivity of mono-sensitive patients with rhinitis in the southern Mediterranean area, in relation to skin reactivity to allergens, total serum IgE levels and blood eosinophils.

OBJECTIVES

The significance of the association between allergic rhinitis, and abnormal airway responsiveness with regard to the pathogenesis of asthma is unclear. For this reason, we have studied non-specific bronchial hyperreactivity, in patients with seasonal allergic rhinitis, with reference to the responsible allergen. The aim of the study was to correlate the responsiveness to bronchoprovocation with methacholine in subjects a with allergic rhinitis during and out of the pollen season with total serum IgE and blood eosinophils.

METHODS

Fourty-nine non-smoking patients with clinical diagnosis of allergic rhinitis and mono-sensitive skin-prick tests to pollen allergens were enrolled in the study. Twenty patients suffered from seasonal rhinitis to Parietaria pollen, 15 patients to Gramineae pollen and 14 patients to Olea pollen. In all patients lung function measurements (assessed as response to methacholine), total serum IgE and blood eosinophil counts were measured during and out of the pollen season.

RESULTS

During pollen season, 16 out of 49 rhinitis patients demonstrated values of bronchial responsiveness measured as response to inhaled methacholine in the asthmatic range whereas out of the pollen season only eight patients were in the asthmatic range. By analysing the results with reference to the responsible allergen, during the pollen season 15 out of 16 patients were Parietaria-sensitive and out of the pollen season seven out of eight patients. Finally, in Parietaria-sensitive rhinitis bronchial responsiveness significantly correlated, during and out of the pollen season, with total serum IgE and with blood eosinophil counts.

CONCLUSIONS

Our results are consistent with the hypothesis that Parietaria is more important than Olea and Gramineae as a risk for developing non-specific bronchial hyperresponsiveness. On the whole, present observations provide further evidence that there is an interrelationship of allergen kind, total serum IgE, eosinophil and bronchial hyperresponsiveness suggesting that they may play a role in the development of bronchial asthma in rhinitis patients.

Rat tibial osteoblasts III: propagation in vitro is accompanied by enhancement of osteoblast phenotype

Postproliferative confluent cultures of primary rat tibial osteoblasts (ROB), cultured in medium supplemented with ascorbic acid and beta-glycerophosphate (AS-bGP, differentiation medium) express, in sequence, specific bone markers which identify a succession of maturation stages, and eventually form mineralized noduli. We report an investigation on the effect of extensive proliferation in vitro in unsupplemented medium on the osteogenic potential of mass cultures of ROB. The growth rates of the populations, derived from two independent primary cultures, was constant throughout 110 cumulative population doublings (CPD) in culture. Propagated cells maintained features similar to osteoblasts in primary cultures with respect to serum and anchorage dependence for growth and to the chemokinetic effect on endothelial cells exerted by their conditioned media (CM). Propagated populations, set at confluence in differentiation medium, were tested for the expression of early [alkaline phosphatase (AP)] and late [osteocalcin (OC); bone sialoprotein (BSP); 45Ca incorporation and mineralization] osteogenic markers. We observed an increase, parallel to the increase in CPD, in both the level of maximal expression of AP (enzyme/microgram cellular DNA) and in the frequency of nodules, reaching five- to sixfold (at 78 CPD) and eightfold (at 60 CPD), respectively, the levels of primary cultures. AP expression (enzyme and mRNA) persisted during mineralization and 45Ca incorporation. The time required by propagated cultures for the formation of nodules decreased with increase of CPD, and was reduced to less than one third at 87 CDP. Nodules became mineralized over a similar lapse of time as in primary cultures and were positive by histochemistry for BSP and OC. We also obtained osteogenic clones from two independent cultures after 72 CPD. 90% of these showed an osteoblast phenotype, expressing AP and forming nodules positive for OC and BSP, which mineralized. Timing of formation and frequency of nodules/plated cells in clones was similar to that found in propagated cultures of equivalent CPD. In summary, propagated ROB populations and derived clones showed enhanced osteoblast phenotype, possibly due to an increase in osteogenic cells and enrichment of proliferating mature osteoblasts, consequent to extended propagation in culture.

Defective expression of CD95 (FAS/APO-1) molecule suggests apoptosis impairment of T and B cells in HLA-B8, DR3-positive individuals

Activation-induced apoptosis is one of the primary control mechanisms for the negative selection of an immune response, leading to maintenance of immune homeostasis and selective T cell deletion. The interaction between the surface molecule Fas and its ligand (FasL) has been proposed as a primary mechanism initiating T cell apoptosis. The T cell receptor modulates the expression and function of these molecules. Defects in the Fas/FasL apoptosis pathway have been shown to result in autoimmune disease in humans and in murine models. Because subjects carrying the HLA-B8, DR3 haplotype show a number of immune dysfunctions, including membrano-proliferative glomerulonephritis, systemic lupus erythematosus, Graves' disease, and others, we investigated Fas expression on T and B cells, and sensitivity to Fas-mediated apoptosis of activated T cells, to determine whether abnormalities of the Fas pathway might be associated with the development of autoimmune diseases in this group of individuals. Our findings show that B cells and resting T cells from HLA-B8+, DR3+ subjects express markedly reduced levels of Fas compared with those isolated from HLA-B8-, DR3+ individuals. Reduced levels of Fas were also evident on the surface of T cells from HLA-B8+, DR3+ subjects activated in vitro by stimulation with OKT3 and phytohemoagglutinin. Cycling T cells from these subjects, evaluated for apoptotic nuclei by flow cytometry after incubation with a cytolytic anti-Fas mAb, showed a significantly lower percentage of Fas-mediated apoptosis than did those from HLA-B8-, DR3- individuals. Normal levels of apoptosis were restored after exposure to a synthetic ceramide analog (C2). Further elucidation of the interaction of these molecules in autoimmune diseases may lead to better understanding of the pathogenesis of these disorders.

HLA-B8,DR3 haplotype affects lymphocyte blood levels

The number of lymphocytes in the blood is constant, pointing to an effective control of circulating lymphocyte values. The mechanisms of this regulation are uncertain, although it is likely that the number of blood lymphocytes is conditioned by hormones, homing factors and cytokines whose production is at least partly restrained by genetic factors. Particularly genetic factors linked to major histocompatibility complex (MHC) appear to be involved. In human beings a decreased number of blood lymphocytes has been described in healthy subjects carrying the Human Leucocyte Antigens (HLA) haplotype HLA-B8,DR3. In the present study, to inquire into the mechanisms of this lymphocyte decreased number, we have performed an analysis of blood subset values in these subjects. When the absolute values of lymphocytes were analysed according to HLA phenotype, HLA-B8,DR3 positive subjects (N = 26) displayed significantly lower values as compared to HLA-B8,DR3 negative ones (N = 282). The analysis of lymphocyte subpopulations performed by flow cytometry in 72 subjects did not show significant changes in lymphocyte subset percentages between HLA-B8,DR3 positive subjects and negative ones. Thus, the decrease of circulating lymphocytes seems to be due to a reduction of cell number affecting all lymphocyte subsets rather than a single cell subpopulation. The analysis of in vitro spontaneous apoptosis performed by flow cytometry in a smaller sample of subjects showed a significant increase of spontaneous apoptosis in lymphocytes from HLA-B8,DR3 positive individuals suggesting a possible explanation for the deviation from normal lymphocyte count observed in these subjects. However it is intriguing that a decreased number of blood lymphocytes can be observed in healthy HLA-B8,DR3 positive subjects but also in autoimmune diseases linked to this haplotype like systemic lupus erythematosus and insulin-dependent diabetes. Furthermore, in our opinion, this finding is to be kept in mind in evaluating hematological parameters in healthy subjects.

Prevalence of organ-specific and non organ-specific autoantibodies in healthy centenarians

In the present study we have investigated the prevalence of organ-specific and non organ-specific autoantibodies in 26 healthy centenarians (6 men, 20 women; age range 101-106 years), using as controls 54 healthy old (33 men and 21 women, age range 71-93) and 56 young subjects (29 men and 27 women, age range 26-60). We assayed sera of each group for the following organ-specific autoantibodies, anti-gastric mucosa (anti-PCA), anti-thyroglobulin (anti-Tg) and non organ-specific autoantibodies, anti-cardiolipin (anti-APA IgG and IgM), anti-nuclear antigens (anti-ANA), anti-double strand DNA (anti-ds-DNA), anti-extractable nuclear antigens (anti-ENA). Finally, natural anti-alpha-galactosyl (anti-alpha-GAL) antibodies were also analyzed. As expected, in the old subjects there was a significant increase of prevalence of anti-Tg and anti-PCA autoantibodies. By contrast, in centenarians the prevalence of organ specific anti-Tg and anti-PCA antibodies was not significantly different from that observed in controls aged less than 60 years. The prevalence of non organ-specific autoantibodies anti-APA (IgG), anti-APA (IgM), anti-ANA, was significantly increased both in the elderly and centenarians when compared with the prevalence observed in sera from the young. Anti-ENA and anti-dsDNA antibodies were not detected in all groups studied. Finally, the prevalence of natural anti-alpha-GAL antibodies significantly increases with age, including centenarians. In conclusion, we confirm and extend the results previously obtained by other authors. In fact, as already described, the prevalence of organ-specific autoantibodies in the elderly is not seen after the tenth decade of life. Interestingly, the prevalence of non organ-specific autoantibodies is instead increased in these subjects, suggesting that different mechanisms are involved in the pathogenesis of these autoantibodies. Particularly, these autoantibodies could be the expression of a damaged tissue process rather than of an autoimmune one, as suggested by data concerning natural antibodies.

Osteoblastic cells from rat long bone. II: Adhesion to substrata and integrin expression in primary and propagated cultures

Propagation in vitro of rat tibial osteoblasts (ROB) is accompanied by increased expression of the early osteogenic marker alkaline phosphatase (AP) and maturation of the osteogenic phenotype. In order to establish the pattern of the integrin expressed in ROB during progression to the mature osteoblastic phenotype, we have used biosynthetic, immunoblotting and immunohistochemical assays. We immunoprecipitated from osteoblasts, expanded for 1.5- and 7.5-doubling, alpha 5 beta 1, alpha v beta 3, alpha 3 beta 1, alpha 6 beta 1 and alpha 1 beta 1 integrin heterodimers; furthermore beta 5, alpha 2 and alpha 4 chains were detected by immunoblots and indirect immunofluorescence. alpha v, alpha 1, alpha 6 subunits in most cells, and beta 3 and beta 1 subunits in a minority, were found to be associated with adhesion plaques in osteoblasts of 1.5-, 4.5- and 7.5-doubling grown in the presence of FCS, while all other subunits stained diffusely all the cells. Adhesion to fibronectin (FN), laminin (LN), collagen type I (COL I) and III(COL III) by ROB at different doubling (1.5-11) was dependent on substratum concentration, and after 2.5 h at 55 nM 60% of the cells adhered to all substrata. Arg-Gly-Asp-Ser (RGDS) containing peptides inhibited adhesion of cells differentially, according to substratum; no dependence on extent of progation in vitro was observed. In conclusion, ROB cultured in vitro for 1.5- to 11-doubling had an unchanged pattern of expression of integrin subunits, heterodimer association and cellular distribution. Adhesion specificity and affinity were also unchanged. These results suggest that the phenotypic maturation, detected as an increase in AP expression, is not accompanied by major changes in the potential for cell-matrix interactions, and does not correspond to changes in the type of integrin subunits expressed by osteoblasts.

Morphea after silicone gel breast implantation for cosmetic reasons in an HLA-B8, DR3-positive woman

We describe an HLA-B8, DR3-positive patient with localized morphea after silicone gel breast implantation for cosmetic reasons. We believe that this case suggests that a genetic background, i.e. HLA-B8, DR3 haplotype, is involved in the autoimmune response to silicone.

Major histocompatibility complex regulation of cytokine production

This review describes the phenomenon of the major histocompatibility complex (MHC) control of cytokine production both in experimental animals and in humans. H-2 (mouse MHC) regulates which type of cytokine is selectively produced in response to the hapten trinitrophenyl (TNP). T cells from TNP-immune H-2k mice produce interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-3, IL-5, tumor necrosis factor-alpha (TNF-alpha), IL-10, and very low levels of IL-4 on reexposure to the specific antigen in vitro. By contrast, T cells from H-2d mice produce IL-3, TNF-alpha, IL-10, and IL-4 but very low levels of IL-2, IL-5 and IFN-gamma. As MHC-congenic matched strains (BALB/k and BALB/c) are used, this makes it unlikely that non-MHC genes influence the class of response observed. A similar pattern of haplotype regulation of cytokine production is observed in humans. In fact, peripheral blood mononuclear cells from HLA-B8,DR3-positive and negative individuals differ in their ability to produce IL-2, IL-5, and IFN-gamma on stimulation with the mitogen phytohemagglutinin while producing similar amounts of IL-4, IL-6, and IL-10. The following main considerations emerge from these observations. The MHC/peptide complex generated after antigen immunization, indicates which class of cytokine production is preferentially induced and, therefore, the outcome of the immune response. Furthermore, MHC genotype may affect cytokine production (and then immune responses) by completely different mechanism(s), that is, by an antigen-nonspecific control that does not depend on the ability of MHC molecules to bind in different ways the different peptides. Accurate control of the functional repertoire of an immune response is a critical parameter in response to infections as well as in immunopathology. MHC control of the class of the immune response at the level of cytokine production is a sophisticated way in which this occurs. This control might be involved in adaptive immune responses to infections as well as in immunopathology.

Assignment of protein disulphides by a computer method using mass spectrometric data

We designed a computer program for the assignment of protein disulphides using mass spectrometric data. All the theoretical linear peptides containing from one to three cysteines are generated on the basis of the protein sequence. Their combination ways are determined in order to create all the possible disulphide-bridged fragments containing from two to six cysteines and to calculate their molecular weight. One, two and three S-S bridges per linked fragment were considered, taking into account the possibility that the fragments contain unabridged residues. The mass data obtained from the spectral analysis of peptide mixtures of the digested protein are then associated to the fitting structures of disulphide-bridged peptides, giving rise to the primary output. This output can then be screened by using information on the specificity of the proteolytic agent(s) used and/or any further mass data provided by Edman degradation and/or carboxypeptidase treatment of the peptide mixtures. The need for such a computer aid is discussed and examples of application are given.

In vitro T cell activation in elderly individuals: failure in CD69 and CD71 expression

A large number of T cell dysfunctions have been observed in the elderly. The most widely observed is the inability of these cells to proliferate at a level comparable to T cells from young individuals after stimulation by mitogens. To better characterize T cell impairment, we have focused on the in vitro T cell activation, analyzing by flow cytometry the activation molecules CD69 and CD71 on mitogen-stimulated lymphocytes from young and elderly subjects. The results show that the percentages of CD69+ and CD71 + T cells were significantly decreased in cultures from elderly subjects when compared to values obtained culturing cells from young individuals. The differences observed seem not due to differences in CD4 and CD8 rates in the "old' cells that underwent activation, since, following activation, the pattern of CD4 and CD8 phenotypes was the same in both groups of subjects. Signals from CD69 are relevant in controlling cytokine gene expression because its stimulation leads to interleukin-2 production and increases its receptor expression. The interaction of this cytokine with its cellular receptor is an essential requirement for T lymphocytes to express CD71 and to start proliferation. Thus, a key role in the age-associated impairment of T cell activation could be played by an ineffective modulation of CD69 expression suggesting a defect in the signal transduction pathway of the T cell receptor-CD3 complex in elderly.

Sharing at the major histocompatibility complex affects the secondary sex ratio in differing ways

We analysed the effect of HLA loci on the secondary sex ratio, and investigated whether allele sharing between parents and between mother and child, or child homozygosity, affected the viability of male embryos, which are generally less resistant to unfavourable conditions during pregnancy. The sharing conditions at the B and DR loci showed significantly differing effects: HLA-B seemed to favour female births, while, in pregnancies subsequent to the first, HLA-DR seemed to favour male births. Both HLA-B and DR loci seemed to work through immunological mechanisms.

Determination of the primary structure of homologous proteins by sequence analysis of peptide mixtures

We propose a rapid method to determine the primary structure of a protein knowing the sequence of a homologous protein. The method consists in submitting both the reduced and alkylated proteins to an enzymatic or chemical hydrolysis and performing the sequence analysis of the peptide mixtures. The assessment of the unknown sequence and the degree of identify of the two proteins are reached by comparing the two sequence analyses. The sequences of all the possible peptides present in the two mixtures are reconstructed and the differences in the two sequences are determined. If necessary, the differences can be confirmed by performing a mass spectrometric analysis of the two mixtures. We used this procedure on two homologous proteins of known sequence to furnish an application example of the method.