Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries.

Reliable neutron star mass measurements are key to determining the equation of state of cold nuclear matter, but such measurements are rare. Black widows and redbacks are compact binaries consisting of millisecond pulsars and semi-degenerate companion stars. Spectroscopy of the optically bright companions can determine their radial velocities, providing inclination-dependent pulsar mass estimates. Although inclinations can be inferred from subtle features in optical light curves, such estimates may be systematically biased due to incomplete heating models and poorly understood variability. Using data from the Fermi Large Area Telescope, we have searched for gamma-ray eclipses from 49 spider systems, discovering significant eclipses in 7 systems, including the prototypical black widow PSR B1957+20. Gamma-ray eclipses require direct occultation of the pulsar by the companion, and so the detection, or significant exclusion, of a gamma-ray eclipse strictly limits the binary inclination angle, providing new robust, model-independent pulsar mass constraints. For PSR B1957+20, the eclipse implies a much lighter pulsar (1.81 ± 0.07 solar masses) than inferred from optical light curve modelling.

Effects of developmental lead exposure on the hippocampal methylome: Influences of sex and timing and level of exposure.

Developmental lead (Pb) exposure results in persistent cognitive/behavioral impairments as well as an elevated risk for developing a variety of diseases in later life. Environmental exposures during development can result in a variety of epigenetic changes, including alterations in DNA methylation, that can influence gene expression patterns and affect the function and development of the nervous system. The present promoter-based methylation microarray profiling study explored the extent to which developmental Pb exposure may modify the methylome of a brain region, hippocampus, known to be sensitive to the effects of Pb exposure. Male and female Long Evans rats were exposed to 0 ppm, 150 ppm, 375 ppm, or 750 ppm Pb through perinatal exposures (gestation through lactation), early postnatal exposures (birth through weaning), or long-term postnatal exposures (birth through postnatal day 55). Results showed a significant contribution of sex to the hippocampal methylome and effects of Pb exposure level, with non-linear dose response effects on methylation. Surprisingly, the developmental period of exposure contributed only a small amount of variance to the overall data and gene ontology (GO) analysis revealed the largest number of overrepresented GO terms in the groups with the lowest level of exposure. The highest number of significant differentially methylated regions was found in females exposed to Pb at the lowest exposure level. Our data reinforce the significant effect that low level Pb exposure may have on gene-specific DNA methylation patterns in brain and that this occurs in a sex-dependent manner.

Differential modulation of the in vitro lymphocyte activation pathways by soluble and solubilized placental substances.

Soluble and detergent-solubilized placental extracts were studied for their modulatory effects upon the proliferation of lymphocytes stimulated by various activating agents. It was shown that soluble placental extract (SPE) exerted an inhibitory effect on the lymphoproliferation triggered by alloantigen or LPS but not by Con A or the combined action of PMA + calcium ionophore A 23187. This effect was also observed with SPE precipitated by 30% of ammonium sulfate (SPE30). On the other hand, a solubilized placental extract (SzPE) that was obtained by using octyl-beta-D-glucopyranoside inhibited the stimulation triggered by alloantigen, LPS, and Con A but did not affect the protein kinase C pathway. The modulatory effects were observed not only when SPE (or SPE30) and SzPE were added at the time of culture initiation but also at 24 h before or after the activating agents. Preincubation with SPE30 or SzPE immobilized on plastic surface, however, transduced an enhanced lymphoproliferative response to alloantigen and mitogen Con A but not to LPS. The above results suggest that placental substances exerted their modulatory effects by interfering mainly with the antigen or mitogen lymphoproliferation pathways.

In vitro immunomodulatory effects of placental substances on preparatory MLR and resulting modifications of lymphocyte reactivities.

The immunomodulatory effects of murine placental extracts (PE) were studied in vitro using mixed lymphocyte culture (MLC) and resulting cell-mediated lympholysis (CML). The results showed that preparative cultures in the presence of PE syngeneic to the responding cells led to a low secondary MLR response with a concomitant generation of suppressor cells. At the efferent phase, cells from the same preparative culture showed a weaker cytotoxic activity than controls cultured in the absence of extract. Furthermore, the induction of regulatory cells able to inhibit CTL in vitro activity was also observed. The active substances can be found in the 30% ammonium sulphate precipitate as well as in some gel filtration fractions showing several main bands from 115 to 43 kDa in SDS-PAGE.

Antibody bipolar bridging: isotype-dependent signals given to guinea pig alveolar macrophages by anti-MHC alloantibodies.

Antibody bipolar bridging of a cell membrane is the phenomenon by which an antibody specifically binds to the corresponding membrane antigen through its Fab and concomitantly to a membrane Fc receptor, through its Fc, thus forming a molecular bridge at the cell surface. This phenomenon, already described on mouse mast cells with anti-H-2 IgG1 antibodies and on guinea pig polymorphonuclear leukocytes with anti-GPLA IgG2 antibodies, presently is extended to and studied on guinea pig alveolar macrophages. These cell membranes present class I and class II MHC (GPLA) antigens as demonstrated by protein-A-sheep red blood cell rosetting and ELISA techniques. They also present Fc receptors for IgG2 and IgG1 as shown by an ELISA technique. IgG2 antibodies (but not their F(Ab')2) directed against corresponding class I or class II antigens induce a positive signal on alveolar macrophages, leading them to release H2O2 and superoxide anions as detected by a burst of chemiluminescence. This respiratory burst begins almost immediately, peaks at 4 to 11 min (depending on antibody concentrations), and decreases thereafter. There is a striking dose-effect curve. By contrast, IgG1 antibodies (but not there F(ab')2) induce a negative signal leading to a decrease of the background chemiluminescence. This type of mechanism appears potentially to be of importance in immune regulation.

Immunological relationships between murine surrogate mothers and transplanted embryos, as studied by local GVH reactivity.

C57BL/Ks (H-2d) female mice were transplanted with early (stage 2) embryos of the A/J (H-2a) strain. Spleens from mice exhibiting successful pregnancies were tested at days 16 to 19 of gestation in a local graft versus host (LGVH) assay using (C57BL/Ks X A/J)F1 recipients and proved to be significantly more reactive than virgin controls or mice carrying transplanted syngeneic fetuses. This increased reactivity was specific for the transplanted embryo's strain. Other controls included donors with semi-allogeneic (F1) transplanted fetuses and females naturally pregnant by allogeneic males which did not give reactions significantly different from virgin control spleen cells. Para-aortic lymph node cells (PALN) obtained from the same A/J embryo-transplanted females showed a strong T suppressive activity both on their own spleen cell (SC) reaction as well as on the reaction obtained with virgin SC. This suppressive activity also appeared to be embryo-strain specific. Serological tests revealed the presence of mast cell-degranulating (anaphylactic) antibodies but not of hemagglutinating or complement-fixing cytotoxic activities. The A/J offspring obtained after embryo transfer to C57BL/Ks females presented at the age of two months significantly lower LGVH reactivity against the surrogate mother's strain. The differences in the responsiveness of the mice transplanted with allogeneic embryos compared with those with conventional pregnancies are discussed.

Role of guinea-pig sperm autoantigens in sperm binding to the zona pellucida and oocyte penetration.

In vitro, binding of acrosome-reacted spermatozoa to the zona pellucida of mature guinea-pig oocytes was inhibited by guinea-pig sperm anti-T IgG and antibodies. Anti-P IgG antibodies prevented oocyte penetration without interfering with sperm-zona binding. The fusion of acrosome-reacted spermatozoa with zona-free oocytes was prevented by anti-T IgG and it was diminished by anti-P IgG. In the same conditions anti-S antibodies had no effect in these in-vitro fertilization events. Immunization of female guinea-pigs with P antigen resulted in a significant decrease of the number of tubal cleaved eggs. T antigens were less clearly implicated in fertilization in vivo. This study provides evidence that well characterized autoantigenic molecules of guinea-pig spermatozoa are involved in fertilization events.

Maternal alloimmune reactions towards the murine conceptus and graft-versus-host reaction (GVHR). II. Inhibition of priming by placental extracts.

Gestation can induce a priming for a GVHR towards paternal strain antigens, although this priming is significantly lower than the one induced by experimental immunization. A role has been sought for placental substances in decreasing this priming through immunomodulation. BALB/c (H-2d) spleen cells do not usually induce a systemic, lethal GVHR in DBA/2 (H-2d) newborn mice except when the donors are preimmunized with DBA/2 cells. Placental extracts (as well as RPMI medium or liver extracts used as controls) were added to DBA/2 cells injected into BALB/c mice used as cell donors for GVH induction. The latter's spleen cells, harvested on day 6 after immunization, were used for systemic and local GVHR. In the systemic assay (lethal effect on DBA/2 newborn mice injected i.v. with BALB/c spleen cells) a significant protection was observed. In the local assay (popliteal lymph node assay in F1 hybrids injected with BALB/c spleen cells into the foot-pad) a highly significant inhibition of priming was detected in recipients injected with spleen cells from placental extract-treated donors. The stimulation index was even lower than that obtained with unprimed BALB/c spleen cells. The same type of local GVHR in (CBA/Ca X A/J) F1 hybrids injected with CBA cells led to similar results. In both situations (systemic and local GVHR) the observed inhibition was found to be specific to the priming cell strain. These results support the working hypothesis that placental substances are able to modify the systemic response of an organism towards both H-2 and non-H-2 alloantigens.

Maternal alloimmune reactions towards the murine conceptus and graft-versus-host reaction (GVHR). I. Priming for anti-paternal GVHR by gestation.

In the H-2 compatible (but minor loci-incompatible) BALB/c-DBA/2 strain combination (both H-2d), intravenous injection of 1.3 X 10(7) BALB/c spleen cells from virgin females into DBA/2 newborn mice less than 18 h old does not result in a significant lethal graft-versus-host reaction (GVHR). A strong GVHR (79% lethal) is induced if the BALB/c donors have been preimmunized to DBA/2. Spleen cells from BALB/c mice pregnant by DBA/2 males are also able to induce a significant, but weaker, GVHR (16% lethal) indicating a cellular priming to paternal antigens by gestation. A significant difference exists between anti-DBA/2 GVH reactivity of spleen cells from primiparous (22% lethal) and multiparous (9% lethal) allopregnant BALB/c mice, indicating that the allogeneic boosters of successive allogestations act more on the target-protective side of immunity than on the target-aggressive one. Sera from allopregnant mice (BALB/c X DBA/2) inhibit the GVHR induced by their own cells, while sera from isopregnant ones (BALB/c X BALB/c) have no effect. Thymectomy performed at 6-wk of age, six weeks before gestation did not significantly modify the maternal reactivity. A similar priming by allogestation in the same strain combination was found for local GVHR (induced in adult F1 hybrids) resulting in higher (+132%, P less than 0.005) stimulation indices and seen to be specific for the paternal strain, the indices induced by the same cells being lower (-35%, P less than 0.05) compared to that induced by cells from virgin BALB/c, when injected into irrelevant F1 hybrids (BALB/c X CBA).

Modulation of mouse anti-SRBC antibody responses by placental extracts. II. Antigen specificity and regulatory role of B and T cell populations affected by two distinct placental fractions.

Previous results from our group had shown that when CBA mice are primed to sheep red blood cells (SRBC) in the presence of various doses of placental extract (PE) (or liver extract [LE] as control), their spleen cells injected into normal syngeneic recipients have important immunoregulatory properties. Low doses of PE (0.25 to 4 mg per mouse) induce a marked decrease of the PFC response against SRBC in recipient animals. In contrast, higher doses of PE (8 to 13 mg per mouse) have a potentiating effect on the same response. LE is not different from a saline injection, at any dose. The suppressive and enhancing effects can be reproduced with two distinct placental fractions (PF) of 40 KD and 60 KD, respectively. In the present report, we have studied the requirement for an antigenic stimulation at the same time as the injection of PE, and the antigenic specificity of the subsequent immunoregulatory effects. In addition, we have analyzed the functional properties of the spleen cell populations affected by PE or placental fractions: surface Ig- cells mediate the suppressive effect due to low doses of PE or the 40-KD fraction, whereas surface Ig+ cells are responsible for the enhancing effect due to high doses of PE or the 60-KD fraction. These immunoregulatory activities do not appear to be related to the presence of Ig fragments in PF, because our results have shown that no Ig fragments can be detected in either PF. Surface Ig- T cell populations from spleen cells treated with the 40-KD fraction and antigen have been further separated into Lyt-2- and Lyt-2+ subpopulations. Our results showed that Lyt-2+ cells alone suppress the PFC response anti-SRBC in both normal and irradiated syngeneic recipients. Thus, the injection of a 40-KD PF in the presence of antigen activates splenic T suppressor cells capable of specifically regulating a secondary antibody response in vivo.

[Autograft of bone marrow treated by immunotoxin T 101 for the treatment of T-cell leukemia and lymphoma. Initial clinical cases]. / Autogreffe de moelle osseuse traitée par l'immunotoxine T 101 pour le traitement des leucémies et lymphomes T. Premières observations cliniques.

In order to consolidate a complete or partial remission, 4 patients with T-cell malignancy received cyclophosphamide 120 mg/kg plus total body irradiation, followed by reinfusion of cryopreserved autologous bone marrow purged in vitro by the immunotoxin T 101 (SR 41322) composed of the murine monoclonal T 101 antibody coupled with the A chain of ricin. The immunotoxin was applied in doses of 10(-9) and 10(-8) M for periods of 4 and 20 hours at 37 degrees C. The recovery of CFUc and BFUe progenitors was total following incubation with IT 101, but reduced after cryopreservation (1-15 to 80% for CFUc,-33 to 47% for BFUe), haematopoietic recovery occurred within normal delays, demonstrating that autologous bone marrow pretreated with the immunotoxin can be successfully transplanted. However, the slow increase in lymphocytes and the occurrence of lethal infection in 2 cases indicate that an in-depth study of immunological reconstitution after in vitro treatment of bone marrow with ITT 101 is necessary.

Evolution of alloantibodies and suppressor cells in allografted mice treated for passive enhancement.

The kinetics and quality of the alloimmune reaction were studied in CBA (H-2k) mice treated for passive enhancement of tumor allografts (Sa 1 indigenous of A/J (H-2a or H-2k/d) mice). Serum samples of treated animals were tested for their biological properties relevant to different antibody isotypes in vitro (hemagglutination, complement-dependent cytotoxicity, and anaphylaxis, i.e., mast cell degranulation involving all main Ig isotypes; IgM, IgG2, and IgG1, IgE, respectively) as well as in vivo (allograft enhancement). Spleen cells from these treated animals were examined for their capacity to interfere with the rejection of tumor allografts by adoptive transfers into syngeneic recipients. In vitro, 51Cr release cytolysis assays were performed in order to test their cytolytic and regulatory activities in comparison to rejecting control animals. It has been shown that: grafted mice, pretreated for passive enhancement, kept their grafts longer and synthetized anaphylactic antibodies (mainly IgG1) earlier and at higher titers than normal serum controls, which rejected the same Sa 1 allografts. Mice with enhanced tumors synthetized cytotoxic antibodies (mainly IgG2) later than rejecting controls. Serum samples from treated and control animals, harvested 10 days (early sera) and 30 days (late sera) after grafting, were injected with a "normal dose" (0.2 ml) and a "high" dose (0.4 ml) to new CBA recipients grafted with Sa 1. Early immune sera were only enhancing at high doses when derived from animals previously treated for enhancement (at the low dose both immune sera were enhancing). Late sera, presenting both complement-fixing, cytotoxic (predominantly IgG2), and IgG1 anaphylactic alloantibodies in the two groups, induced enhancement in all cases, but more strongly when derived from the group treated for Sa 1 enhancement. Adoptive transfer of spleen cells from animals treated for passive enhancement were able either to inhibit the accelerated rejection (Day 10) or to promote enhancement of Sa 1 allogeneic cells (Day 30) while similar cells taken (Day 10 and Day 30) from control graft-rejecting mice transferred accelerated rejection. Among the transferred T-cell sub-populations, the suppressive effect was mediated by Lyt 2 T cells. In vitro, these spleen cells showed a weaker cytolytic activity than those of allograft-rejecting mice. Moreover, they were able to regulate the cytolytic activity of cytotoxic effector cells from specifically immunized CBA mice.

Cellular transfer of autoimmune aspermogenic orchiepididymitis (AIAO) by the i.v. route in the guinea pig.

In this study, AIAO was adoptively transferred with a high proportion of success to syngeneic recipient guinea pigs. Donors of strains 2 and 13 were sensitized with a series of spermatozoal autoantigens (whole spermatozoa and three autoantigens isolated therefrom: S, P and T). Syngeneic (experimental) and allogeneic (control) recipients were all transferred by strictly i.v. injections of lymphoid cells. The damage observed in testis and epididymis (mainly in the latter) was identical to, but milder than, that seen in active forms of AIAO. The incidence and severity of the disease were dependent on: the type of inducing antigen, S, T, P in order of decreasing efficiency; the length of immunization in donors, with increasingly serious lesions as periods ranged from 1 to 4 weeks; the presence or not of a complementary treatment of recipients with bacterial adjuvant enhancing the disease. Other parameters were less important, such as the strain 2 or 13 specificities, the amount of immunogen or the addition of peritoneal cells to lymph node cells. Skin hypersensitivity was concomitantly transferred to a large majority of isogenic recipients. But the incidence and severity of the disease showed only a partial correlation with Arthus type or delayed type responses to autoantigens. Thus guinea pig AIAO, already known to be transferable by immune sera (mainly anti-P and also anti-T) may also be transferred in physiological conditions by sensitized lymphoid cells (mainly anti-S and also anti-T).

Deviation of humoral and cellular alloimmune reactions by placental extracts.

Modifications of the alloimmune response at both the humoral and the cellular levels by placental extracts (PE) syngeneic to the recipient were studied in the mouse using two different H-2 strain combinations. CBA (H-2k) or C57BL/Ks (H-2d), immunized with A/J (H-2a) spleen cells. The tests included in vivo tumor allograft evolution (accelerated rejection or enhancement reactions), and in vitro analysis of the involved immune agents, both cellular and humoral, using mixed lymphocyte reactions (MLR) and biological activity studies of serum samples. Animals from the recipient strains exhibited a delayed rejection of A/J tumor Sa 1 allografts if preimmunization was carried out with 10(6) A/J spleen cells combined with PE syngeneic to the recipients, as compared to controls immunized with A/J cells only or supplemented with isogeneic liver extracts (LE). The serological analysis revealed that PE treatment did not modify the overall hemagglutinating antibody production but resulted simultaneously in both a decreased production of cytotoxic complement fixing antibodies and an increase of specific anaphylactic mast cell degranulating antibodies, as compared to controls. The sera from PE-treated donors also demonstrated enhancing activity following passive transfer to isogeneic recipients. MLR regulatory activity was exhibited by spleen cells from PE- and immunogen-treated mice although the same or stronger activity was obtained from mice immunized without the addition of PE. However, in vivo transfer of these cells to syngeneic recipients showed that PE treatment erased the accelerated rejection caused by allogeneic immunization in the absence of PE and could even cause some degree of allografted tumor enhancement. The cells responsible for this inhibitory effect were mainly IJ+ lymphocytes, since their elimination with a relevant anti-IJ serum and complement restored a secondary type rejection pattern. These results show that PE present during the onset of immunization can promote the activation of regulatory agents such as enhancing antibodies and suppressor cells favoring allograft survival.

Evidence for absence of toxicity of T101 immunotoxin on human hematopoietic progenitor cells prior to bone marrow transplantation.

T101-ricin A-chain immunotoxin is a hybrid molecule made up of the T101 monoclonal antibody bound to the A-chain of ricin. It specifically destroys cells expressing the cell surface T65 antigen. We have designed a preclinical study to evaluate its possible use for the in vitro treatment of T-cell hematological cancers prior to autologous bone marrow transplantation. The data presented here show that conditions previously defined to produce high tumor cell killing, i.e., a 20-hr incubation at 37 degrees in the presence of T101-ricin A-chain immunotoxin up to 10(-7) M in a 10 mM ammonium chloride solution, do not affect the in vitro proliferative capacity of human hematopoietic stem cells studied by means of semisolid medium cultures (granulocyte-macrophage progenitors, burst-forming units-erythrocyte) and continuous liquid cultures (pre-granulocyte-macrophage progenitors). Therefore, autologous bone marrow transplantation with T101-ricin A-chain immunotoxin-treated graft should be feasible.