Mast cells enhance proliferation of B lymphocytes and drive their differentiation toward IgA-secreting plasma cells.

The evidence of a tight spatial interaction between mast cells (MCs) and B lymphocytes in secondary lymphoid organs, along with the data regarding the abundance of MCs in several B-cell lymphoproliferative disorders prompted us to investigate whether MCs could affect the proliferation and differentiation of B cells. To this aim, we performed coculture assays using mouse splenic B cells and bone marrow-derived MCs. Both nonsensitized and activated MCs proved able to induce a significant inhibition of cell death and an increase in proliferation of naive B cells. Such proliferation was further enhanced in activated B cells. This effect relied on cell-cell contact and MC-derived interleukin-6 (IL-6). Activated MCs could regulate CD40 surface expression on unstimulated B cells and the interaction between CD40 with CD40 ligand (CD40L) on MCs, together with MC-derived cytokines, was involved in the differentiation of B cells into CD138(+) plasma cells and in selective immunoglobulin A (IgA) secretion. These data were corroborated by in vivo evidence of infiltrating MCs in close contact with IgA-expressing plasma cells within inflamed tissues. In conclusion, we reported here a novel role for MCs in sustaining B-cell expansion and driving the development of IgA-oriented humoral immune responses

Ten-year results of a Screening Program during pregnancy for children’s dental caries prophylaxis

Introduction: Dental caries is a multifactorial disease with many contributing factors in the genesis of risk (11). Streptococcus mutans (SM) is a gram positive, facultative anaerobe commonly found in the human oral cavity. Described for the first time in 1924 by Clarke, is the main germ responsible for the caries disease (5, 9). In fact, SM produces an insoluble extracellular polysaccharide sucrose which plays an important role as a mediator of the adhesiveness, both as a cementing molecule for other microorganisms, and to create a protected site where the microorganism can proliferate (6, 9, 10). Its presence in the plaque is not equal for all people and is closely related to sugar consumption (9). Its transmission can take place early in the life of the child through the mother’s saliva (2, 3, 4, 8).The early acquisition of this organism is associated with Early Childhood Caries (ECC) and then creates a primary colonization which is hardly removed (1, 7). Paying special attention to the health of women and children, this work aimed to decrease the incidence of childhood tooth decay, streamlining preventive efforts in a population at risk. Methods: Since 1999, all women referred to our clinic in the second trimester of pregnancy or during childbirth were offered the opportunity to perform a simple test to measure the presence of SM in saliva and have been given some advice (diet, hygiene, fuoro-prophylaxis, dental visit). The sampling of saliva was performed after chewing one paraffin tablet for about 1 minute. For the microbiological examination the technique of dip-slide test (CTR bacteria, Ivoclar Vivadent) was used; results were classified according to semi-quantitative classes of microorganism concentration.Women were classified positive when bacterial concentration was 100000 CFU/ml. Besides a general advice on hygiene and diet, these women were invited to undergo a prophylactic treatment with chlorhexidine, a disinfectant with bactericidal properties against SM. Results: 84% of surveyed women adhered to the screening (29% pregnant women, 55% in the puerperium). In the 12-year study, 2170/7213 (30%) women had a positive saliva test and were administered chlorhexidine. Conclusions: By means of a prenatal screening involving different professionals (microbiologist, obstetriciangynecologist, pediatrician, oral-hygienist) we could assess the likelihood of vertical transmission of SM from mother to child, and give the mothers medical advice on the risk of tooth decay in children. Preliminary data on the incidence of caries in children of those women who tested positive at the screening, confirm that our program has an important role in preventing childhood tooth decay

CD4+CD25+ Regulatory T Cells Suppress Mast Cell Degranulation and Allergic Responses through OX40-OX40L Interaction

T regulatory (Treg) cells play a role in the suppression of immune responses, thus serving to induce tolerance and control autoimmunity. Here, we explored whether Treg cells influence the immediate hypersensitivity response of mast cells (MCs). Treg cells directly inhibited the FcεRI-dependent MC degranulation through cell-cell contact involving OX40-OX40L interactions between Treg cells and MCs, respectively. When activated in the presence of Treg cells, MCs showed increased cyclic adenosine monophosphate (cAMP) concentrations and reduced Ca2+ influx, independently of phospholipase C (PLC)-γ2 or Ca2+ release from intracellular stores. Antagonism of cAMP in MCs reversed the inhibitory effects of Treg cells, restoring normal Ca2+ responses and degranulation. Importantly, the in vivo depletion or inactivation of Treg cells caused enhancement of the anaphylactic response. The demonstrated crosstalk between Treg cells and MCs defines a previously unrecognized mechanism controlling MC degranulation. Loss of this interaction may contribute to the severity of allergic responses. © 2008 Elsevier Inc. All rights reserved

VVDS-SWIRE. Clustering evolution from a spectroscopic sample of galaxies with redshift 0.2 < z < 2.1 selected from Spitzer IRAC 3.6 mum and 4.5 mum photometry

International audienceAims:By combining data from the VIMOS VLT Deep Survey (VVDS) with the Spitzer Wide-area InfraRed Extragalactic survey (SWIRE), we have built the currently largest spectroscopic sample of high redshift galaxies selected in the rest-frame near-infrared. We have obtained 2040 spectroscopic redshifts of galaxies with (m3.6)_AB 4.5)_AB Methods: We use the projected two-point correlation function w_p(r_p) to study the three dimensional clustering properties of galaxies detected at 3.6 mu m and 4.5 mu m with the InfraRed Array Camera (IRAC) in the SWIRE survey with measured spectroscopic redshifts from the first epoch VVDS. We compare these properties to those of a larger sample of 16672 SWIRE galaxies for which we have accurate photometric redshifts in the same field. Results: We find that in the 3.6 mu m and 4.5 mu m flux limited samples, the apparent correlation length does not change from redshift ~2 to the present. The measured correlation lengths have a mean value of r0 ~= 3.9±0.5 h-1 Mpc for the galaxies selected at 3.6 mu m and a mean value of r0 ~= 4.4±0.5 h-1 Mpc for the galaxies selected at 4.5 mu m, across the whole redshift range explored. These values are larger than those typicaly found for I-band selected galaxies at I_AB 0 varies from 2.69 h-1 Mpc to 3.63 h-1 Mpc between z = 0.5 to z = 2.1. We find that the difference in correlation length between I-band and 3.6-4.5 mum selected samples decreases with increasing redshift, becoming comparable at z ~= 1.5. We interpret this as evidence that galaxies with older stellar populations and galaxies actively forming stars reside in comparably over-dense environments at epochs earlier than z ~= 1.5, supporting the recently reported flattening of the color-density relation at high redshift. The increasing difference in correlation length with cosmic time observed between rest-frame UV-optical and near-infrared selected samples could then be an indication that star formation is gradually shifting to lower density regions with decreasing redshift, while the older, passively evolving galaxies remain in the most over-dense peaks

VVDS-SWIRE. Clustering evolution from a spectroscopic sample of galaxies with redshift 0.2 < z < 2.1 selected from Spitzer IRAC 3.6 mum and 4.5 mum photometry

International audienceAims:By combining data from the VIMOS VLT Deep Survey (VVDS) with the Spitzer Wide-area InfraRed Extragalactic survey (SWIRE), we have built the currently largest spectroscopic sample of high redshift galaxies selected in the rest-frame near-infrared. We have obtained 2040 spectroscopic redshifts of galaxies with (m3.6)_AB 4.5)_AB Methods: We use the projected two-point correlation function w_p(r_p) to study the three dimensional clustering properties of galaxies detected at 3.6 mu m and 4.5 mu m with the InfraRed Array Camera (IRAC) in the SWIRE survey with measured spectroscopic redshifts from the first epoch VVDS. We compare these properties to those of a larger sample of 16672 SWIRE galaxies for which we have accurate photometric redshifts in the same field. Results: We find that in the 3.6 mu m and 4.5 mu m flux limited samples, the apparent correlation length does not change from redshift ~2 to the present. The measured correlation lengths have a mean value of r0 ~= 3.9±0.5 h-1 Mpc for the galaxies selected at 3.6 mu m and a mean value of r0 ~= 4.4±0.5 h-1 Mpc for the galaxies selected at 4.5 mu m, across the whole redshift range explored. These values are larger than those typicaly found for I-band selected galaxies at I_AB 0 varies from 2.69 h-1 Mpc to 3.63 h-1 Mpc between z = 0.5 to z = 2.1. We find that the difference in correlation length between I-band and 3.6-4.5 mum selected samples decreases with increasing redshift, becoming comparable at z ~= 1.5. We interpret this as evidence that galaxies with older stellar populations and galaxies actively forming stars reside in comparably over-dense environments at epochs earlier than z ~= 1.5, supporting the recently reported flattening of the color-density relation at high redshift. The increasing difference in correlation length with cosmic time observed between rest-frame UV-optical and near-infrared selected samples could then be an indication that star formation is gradually shifting to lower density regions with decreasing redshift, while the older, passively evolving galaxies remain in the most over-dense peaks