Demonstration on protein A of two distinct immunoglobulin-binding sites and their role in the mitogenic activity of Staphylococcus aureus Cowan I on human B cells.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
R Biagiotti
Publications and source records attributed to R Biagiotti.
In vitro production of IgE by human peripheral blood mononuclear cells. IV. Modulation by allergen of the spontaneous IgE antibody biosynthesis.
Peripheral blood lymphocytes (PBL) from a proportion of grass-sensitive patients, studied during or immediately after the grass pollination period, showed spontaneous production in vitro of grass-specific IgE antibody, whereas PBL from atopic patients sensitive to allergens other than grass pollens or non-atopic individuals did not. Pre-incubation of IgE antibody producing PBL from grass-sensitive patients with minute amounts of a mixed grass pollen (MGP) extract or Rye grass antigen Group I (Rye I) usually resulted in a reduction of the spontaneous production in vitro of IgE protein and in a marked inhibition of the spontaneous production in vitro of grass-specific IgE antibody. This antigen-specific inhibition was not mediated by T lymphocytes, but it was apparently due to a signal directly delivered by antigen to the spontaneously IgE antibody producing cells. The results support the concept that the activity of cells responsible for the persistent IgE antibody formation in vitro in atopic patients can be modulated by antigen.
Antibody Specificity↗
Protein A reactivity of IgM- and IgD-bearing lymphocytes from some patients with chronic lymphocytic leukemia.
Explore the source record for details and available documents.
Animals↗
Surface immunoglobulins are involved in the interaction of protein A with human B cells and in the triggering of B cell proliferation induced by protein A-containing Staphylococcus aureus.
The nature of surface components responsible for the reactivity of a subset of human B cells with staphylococcal protein A (SpA) was studied. The ability of normal non-T cells or non-T cells from patients with chronic lymphocytic leukemia (CLL) to form rosettes with human red blood cells coated with SpA (SpA-HRBC) was strongly inhibited or abolished by incubation with F(ab')2 fragments of antibodies against human immunoglobulin (Ig), whereas the incubation with F(ab')2 fragments of antibodies against a non-Ig cell surface antigen, such as beta 2-microglobulin, had no effect on the SpA-rosetting of human lymphocytes. The role of the reaction between surface Ig (sIg) and SpA in the triggering of the proliferative response induced by Staphylococcus aureus bacteria strain Cowan I (Cowan Staph) on normal or leukemic non-T cells was also investigated. A parallelism was observed between the mitogenic activity on normal human non-T cells of Cowan Staph and F(ab')2 fragments of immunosorbent-purified rabbit antibodies to human mu-chain. On the other hand, monovalent Fab fragments of anti-F(ab')2 or anti-mu chain antibodies were unable to activate human non-T lymphocytes, but usually induced a partial inhibition of the Cowan Staph-induced cell proliferation. Non-T cells from 2 patients with CLL did not respond to either Fab or F(ab')2 fragments of anti-Ig antibodies, but were stimulated to proliferate by Cowan Staph. However, the proliferative response of non-T cells from these patients to Cowan Staph was markedly inhibited or abolished by the addition to the cultures of F(ab')2 fragments of anti-Ig antibodies. Antibody preparations to human F(ab')2 or gamma-chain inhibited the response of IgG-bearing leukemic cells, whereas the Cowan Staph-induced proliferation of IgM-bearing leukemic lymphocytes was inhibited by the addition to the cultures of either anti-F(ab')2 or anti-mu chain antibodies. The proliferative response to Cowan Staph or normal non-T cells was also inhibited by the addition to the cultures of human and guinea pig polyclonal IgG, whereas IgG from other species, such as goat, ox, horse, and rabbit, were poorly or not at all inhibitory. On a molar basis, the F(ab')2 preparation from human IgG was as potent an inhibitor as intact IgG molecules, whereas Fc gamma was much less effective in inhibiting the Cowan Staph-induced cell proliferation. A monoclonal IgM, isolated from the serum of a patient with CLL, whose lymphocytes were able to form rosettes with SpA-HRBC and to proliferate in vitro after stimulation with Cowan Staph, also showed a marked inhibitory activity on the Cowan Staph-induced proliferation or normal non-T cells. These data suggest that an interaction between SpA present on the bacterial cell wall and a structure located in the Fab region of sIg, which is shared by sIgM, sIgG, and perhaps also by sIg of other classes, plays an important role in the triggering of B cell proliferation induced by SpA-containing staphylococci.
Antibodies↗
Hyperproduction of IgE and T-cell dysfunction in Hodgkin's disease.
Serum IgE levels were evaluated in 119 untreated and 112 treated patients with Hodgkin's disease (HD). 38 of the nonatopic untreated patients showed significantly increased (> 300 IU/ml) IgE concentrations. No relationship could be found between increased IgE levels and depressed lymphocyte response to phytohemagglutinin (PHA) or the imbalance of TM and TG lymphocyte subsets. On the other hand, the mean level of suppressor activity elicitable from cells of untreated HD patients by concanavalin A preincubation did not differ significantly from that of healthy control subjects. In contrast, in treated patients, where there was a significant reduction in the number of circulating T lymphocytes, a further depression of the lymphocyte response to PHA, a more marked disproportion of TM and TG cell subsets and a noticeable fall in IgE concentration was found. These data suggest that increased IgE concentrations seen in untreated patients with HD are unrelated to the T-cell defects. They also suggest that hyperproduction of IgE is probably not invariably a consequence of a suppressor cell deficiency.
Cell Division↗
Study of some properties of the receptor for IgM on human lymphocytes.
Some properties of the receptor for IgM on human lymphocytes have been investigated. It was shown that the interaction of native IgM with the receptor present on T and B lymphocytes is not critical for its detection in the EAM-rosette assay. In fact, high values of EAM-RFC could be found on cell suspensions cultured overnight in either IgM-free or IgM-containing media. In addition, the inhibition of EAM-rosettes by human monoclonal IgM at 37 degrees C was not as effective as at 4 degrees C. Rabbit IgM showed a significantly greater ability to inhibit the binding of antigen-IgM antibody complexes than human IgM. The receptor for IgM was easily removed by handling procedures, the incubation of lymphocytes at 4 degrees C and treatment of the cells with low concentrations of trypsin or pronase. After the enzymatic treatment, a rapid resynthesis occurred, which restored the number of EAM-rosettes formed by T cells and significantly increased the number formed by B cells. The interaction between the receptor and antigen-IgM antibody complexes stopped the spontaneous shedding of the receptor at 4 degrees C. When the incubation of the cells with immune complexes was performed at 37 degrees C, a significantly different behaviour between T cells equipped with receptor for IgM and those possessing receptor for IgG was found. After the binding of EAG to the receptor for IgG, a process of rapid dissociation of rosettes occurred, whereas the incubation with EAM did not induce an irreversible loss of the receptor for IgM.
Antigen-Antibody Complex↗
Altered proportion of T mu-and T gamma-cell subpopulations in patients with Hodgkin's disease.
The ability of peripheral blood lymphocytes from patients with Hodgkin's disease (HD) to form rosettes with ox red blood cells (ORBC) sensitized by anti-ORBC purified rabbit IgM and IgG was investigated. The mean percentage of cells capable of forming rosettes with ORBC coated with IgM (EAIgM-RFC) in the peripheral blood of either untreated or X-ray-treated patients with HD was significantly lower than that of normal individuals. In the same groups of patients with HD the mean percentage of T lymphocytes equipped with receptor for IgG (T gamma lymphocytes), evaluated by a mixed fluorescent rosette assay, was significantly higher than in normal controls. These data suggest that the altered proportion between T mu-and T gamma-cell subpopulations in patients with HD probably represents a disease-related phenomenon.
Adolescent↗
Receptors for IgM: a feature of subpopulations of both T and B human lymphocytes.
Receptors for IgM were detected on peripheral blood and tonsil human lymphocytes by a rosette technique with ox red blood cells (ORBC) coated with anti-ORBC rabbit IgM. It was found that the receptors are very sensitive to handling procedures of cells and to low temperatures. An overnight incubation period at 37 degrees C was the optimal condition for the maximum expression of receptors for IgM, but the use of IgM-free media in these cultures was neither an essential nor favourable factor for an optimal rosette formation, when ORBC heavily coated with rabbit IgM were used. The great majority of chronic lymphocytic leukaemia (CLL) patients presented a high number of EA(IgM)-RFC, either on freshly drawn or cultured lymphocytes. By fractionation procedures of normal peripheral blood and tonsil lymphocytes, it was found that a subpopulation of B cells, like T cells, also posses a lower avidity for IgM than those present on T lymphocytes.
B-Lymphocytes↗
Different mitogenic activity of soluble and insoluble staphylococcal protein A (SPA).
The response to SPA and Staphylococcus strain Cowan I (StaCw) of highly purified populations of peripheral blood and tonsil human lymphocytes was investigated. Purified T lymphocytes isolated from perpheral blood by E-rosetting were unable to respond in vitro to StaCw. Highly purified B-cell populations from tonsils did not show any proliferative response in the presence of soluble SPA. The addition to highly purified B-cell suspensions from human tonsils of increasing concentrations of autologous T lymphocytes did not induce any increase of thymidine uptake in the presence of StaCw. However, it was able to restore a marked proliferative response of the B-cell cultures to soluble SPA, even though mitomycin-treated T lymphocytes were added. The low response of highly purified peripheral blood T lymphocytes to soluble SPA could be potentiated by the addition of autologous mitomycin-treated B cells, whereas the unresponsiveness of purified T lymphocytes to StaCw was not affected. Mitogenic activity of SPA coupled to Sepharose beads was different from that of soluble SPA and paralleled that of StaCw. These data strongly suggest that insoluble SPA is a T-cell-independent B-cell mitogen in man, whereas soluble SPA, like PWM, exerts its activity on B cells only in the presence of T cells.
B-Lymphocytes↗
Study of some immunological parameters in untreated patients with Hodgkin's disease.
Explore the source record for details and available documents.
Adolescent↗
Alterations of both responder T cells and stimulator non-T cells are responsible for abnormal mixed lymphocyte reaction in aged humans.
The autologous and allogeneic mixed lymphocyte reactions of 15 young and 15 aged human adults were compared. Both autologous and allogeneic mixed lymphocyte reactions were significantly reduced in the aged group. T cells from aged adults displayed a reduced proliferative response to non-T cells of either aged or young adults. T cells from young adults also showed a reduced proliferative response to non-T cells from aged adults. Sera from aged adults, showing depression of autologous and allogeneic mixed lymphocyte reaction, did not exert any inhibitory effect on the autologous and allogeneic mixed reaction of lymphocytes from young donors. These data suggest that depression of mixed lymphocyte reaction in aged humans probably reflects intrinsic abnormalities of both responder T cells and stimulatory non-T cells.
Adult↗
Placental morphometry in pregnancies complicated by intrauterine growth retardation with absent or reversed end diastolic flow in the umbilical artery.
The aim of this study was to assess any possible correlation between villous tree architecture and its vascularization, and absent or reversed end-diastolic flow velocity (ARED) in the umbilical artery. The study group included seven pregnancies complicated by IUGR (estimated fetal weight < 10th percentile) and absent end-diastolic flow velocity in the umbilical artery. A gestational-age matched group of seven normally grown pregnancies was selected as control group. At delivery, the placenta was weighed and immersed in 10% neutral buffered formalin. A stratified random sampling procedure was used to obtain 12 blocks of full-thickness tissue per organ. A single random section was cut from each block. The following morphometric parameters were evaluated in each section: mean vessel diameter, volume density of the villous tissue, stem villi and terminal villi. Measurements were performed using a computerized Video Image Analysis system. No significant difference in mean vessel diameter was found between the two groups (37.1 microns versus 36.1 microns; p = 0.1). There was a significant reduction in the proportion of total villous tissue in the ARED group (43% versus 52%): this was due to a significant reduction in the volume of tissue occupied by the terminal villi (14.1% versus 18.4%). No significant difference was found in the proportion of villous tissue occupied by the stem villi (42% versus 40%). Several studies have investigated the anatomical and/or vasomotor bases of absent end diastolic flow velocity in the umbilical artery of fetuses with severe IUGR. Our observations of a significant reduction in the proportion of villous tissue occupied by the peripheral villi are consistent with the theory that failure of normal development of the terminal villous is responsible for the increased vascular resistance in IUGR pregnancies with ARED.
Chorionic Villi↗
Functional and ultrastructural features of DNA-fragmented human sperm.
The functional significance of deoxyribonucleic acid (DNA) fragmentation in ejaculated human sperm is unclear. In this study the extent of DNA strand breakage in swim-up selected spermatozoa was evaluated by terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick end labeling (TUNEL)-coupled flow cytometry and correlated with several functional and morphological sperm parameters. The extent of DNA fragmentation (mean = 11.07%+/-8.00%, range = 0.79%-42.64%, n = 140) was positively related to abnormal morphology and associated with defects of the sperm tail. A negative correlation was found between DNA breakage and progressive motility. When a stepwise multiple linear regression model was used to analyze the relationship between DNA fragmentation and the aforementioned parameters, only motility results were included in the model. The presence of spermatozoa showing submicroscopic characteristics resembling those of somatic apoptosis has been reported in human ejaculate. To verify whether sperm DNA fragmentation was associated with the presence of such apoptotic-like cells, we performed electron microscopy and TUNEL-coupled flow cytometry in a limited number of sperm samples (n = 24). Although we did not observe any significant relationship between DNA breakage and the characteristics that are suggestive of apoptosis, an association was found with several ultrastructural features, indicating an impaired motility. Hence, we conclude that in ejaculated sperm, DNA fragmentation does not correspond to the apoptosis-like phenomenon and that it is associated with defects of motility.
Cell Size↗
[Usefulness and limits of a fetal biophysical profile in the management of pregnancy at risk].
Usefulness and limits of fetal biophysical profile (BPP) were determined in 132 high-risk pregnancies, evaluating the relationship between the last biophysical profile result and perinatal outcome. The presence of a low incidence of perinatal complications when BPP is normal permits the conservative management of these pregnancies. When the score is abnormal instead, there is also high false positive rate that may determine an unnecessary intervention with associated perinatal morbidity. On the other hand, BPP seems to become abnormal relatively late in the chronic asphyxial process, when it may be impossible to prevent mortality or a serious perinatal morbidity: its association with other tests is therefore necessary for a better evaluation of fetal risk.
Female↗
The Fc epsilon R2/CD23 antigen: a hallmark of chronic lymphocytic leukemia B cells.
The effect of different stimuli on the expression of the low-affinity receptor for the Fc fragment of IgE (Fc epsilon R2/CD23) on peripheral blood B cells from patients with chronic lymphocytic leukemia (CLL) was investigated. CLL B cells cultured for 3 days in medium alone showed a progressive decrease of the Fc epsilon R2/CD23 expression, while the addition to the cell cultures of IgE or interleukin-4 had a slackening effect on the decrease of the Fc epsilon R2/CD23. In contrast, in the presence of interferon-gamma the proportion of Fc epsilon R2/CD23+ cells was more rapidly reduced compared to CLL B cells cultured in medium alone. Stimulation of CLL B cells with Staphylococcus aureus Cowan I (SAC) bacteria, which are able to enhance the expression of Fc epsilon R2/CD23 on normal B cells, induced a rapid loss of the Fc epsilon R2/CD23 from CLL B cells.
Antigens, Differentiation, B-Lymphocyte↗
[Lunar phases and incidence of spontaneous deliveries. Our experience].
OBJECTIVE: To evaluate the relationship between lunar phases and birthrate. STUDY DESIGN: We examined 7842 spontaneous deliveries at Obstetric and Gynaecologic Clinic of University of Florence, between January 1988 and November 1992, covering 58 synodic lunar months. A lunar month was considered to be a period of 29.5 days and comprised four lunar phases: the full moon, the last quarter, the new moon and the first quarter. We compared the median number of births in each day of synodic month and in the periods of seven days centered on the first day of each moon phase. Statistical analysis was performed using the Kruskal-Wallis one-way analysis by ranks. RESULTS: Non significant differences were found in the incidence of spontaneous birth throughout the lunar cycle. CONCLUSIONS: These results do not support the hypothesis of a relationship between moon-phase changes and the incidence of spontaneous deliveries.
Adult↗
Anatomical-radiological and morphometric analysis of the lateral atlantoaxial joint.
The width of the articular space of the lateral atlantoaxial joint was measured to evaluate normal range values and possible variations according to age and sex. The study was based on X-rays of the lateral atlantoaxial joint of 52 females (age range: 18-82 ys) and 50 males (age range: 20-82 ys). The radiograms were taken using a semiautomatic computerized morphometric system (Videoplan II, Image Analysis system-Kontron, Munich, Germany). The articular space width of the lateral atlantoaxial joint was measured on both sides, at the medial, lateral and median levels. The mean value at these levels, on both sides, was calculated. Regression analysis was performed to evaluate the relationships between the width of the articular space at the three different levels and the patient's age and gender. No significant differences were found in the mean values of the articular space width at the three levels as regards gender. However, a significant inverse correlation was found between the articular space width and the patients' age in both males and females. Comparative analysis of regression lines showed that the slope of these lines was not significantly different when the sexes were compared. On the contrary, the intercept of the regression lines at the medial and median levels was significantly higher in the females than in the males; the contrary was encountered at the lateral level. This feature is probably due to the different types of inclination of the articular facets of the axis or of those of the atlas in the two sexes.
Adolescent↗