Influence of Nitric Acid on the Helium Ion Radiolysis of Aqueous Butanal Oxime Solutions.

Samples of butanal oxime in aqueous nitric acid solutions have been irradiated with the helium ion (4He2+) beam of the CEMHTI (Orléans, France) cyclotron. The consumption yield of butanal oxime has been measured by gas chromatography coupled with mass spectrometry. Gaseous products (mainly H2 and N2O) have also been monitored by micro-gas chromatography. Yields of liquid phase products (hydrogen peroxide and nitrous acid) have been determined by colorimetric methods. The influence of nitric acid on the radiation chemical behavior of butanal oxime depends on the nitric acid concentration. For a low concentration (≤0.5 mol L-1) butanal oxime is protected by the nitrate ions, which can efficiently scavenge the water radiolysis radicals. For higher concentrations, nitrous acid can accumulate in the medium, therefore leading to a strong increase of the butanal oxime degradation. The associated mechanism is an autocatalytic oxidation of butanal oxime by HNO2.

Characterization of two infectious mouse mammary tumour viruses: superantigenicity and tumorigenicity.

Mouse mammary tumour virus (MMTV) is a type B retrovirus that causes mammary tumours in susceptible mice. MMTV encodes a superantigen (SAg) that has the property of stimulating T-cell populations expressing a particular variable region of the T-cell receptor (TCR) beta chain (Vbeta) and needs to be presented in the context of major histocompatibility complex (MHC) class II molecules. Previously, we described two exogenous MMTV, MMTV BALB14, which encodes a superantigen that induces the deletion of Vbeta14+ Tcells, and MMTV BALB2, which encodes a SAg that induces the deletion of Vbeta2+ Tcells. We now describe their biological activity: the deletions involve both CD4+ and CD8+ populations, are progressive and can be detected in blood, lymph nodes and spleen. Such deletions reflect, at least in part, those occurring during intrathymic development. Both BALB2 and BALB14 viral variants are capable of inducing a strong increase of Vbeta-specific T cells in BALB/c mice (I-A+, I-E+). However, when injected into the footpad, their initial stimulatory capacity differs in that the presence of MHC I-E molecules is essential only for the stimulation of Vbeta2+ T cells. Both viral variants are able to induce deletion even in the absence of the I-E molecule in which case, however, deletion appears later and is less pronounced. Both exogenous MMTVs induce, at the end of a year, 30-35% of pregnancy-dependent mammary adenocarcinomas.

[Superantigens and retroviral infections. Increase of mammary tumorigenicity due to recombination between exogenous and endogenous MMTV viruses]. / Superantígenos e infecciones retrovirales. Aumento de la tumorigenicidad mamaria por recombinación entre virus MMTV exógenos y endógenos.

A number of milk-borne exogenous mouse mammary tumor viruses (MMTV) infect mice shortly after birth and, when expressed, produce superantigens. Herein we describe the biological effects of new variants of exogenous MMTV: one of them (BALB14) present in BALB/c mice and showing a low ability to induce mammary tumors, and the other (MMTV-7) being the result of recombination between the BALB14 and the Mtv-7 endogenous provirus. The recombinant virus which has the SAg-specificity of Mtv-7 was amplified in BALB/c mice this fact correlating with a high incidence of mammary tumors. The role of strong SAgs in the mechanism by which the recombinant virus increases its title in a susceptible host is discussed. The results obtained suggest that the presence of non-productive endogenous proviruses--considered as conferring a selective advantage to the mouse population by protecting it from infection with exogenous MMTV--should also be advantageous to the pathogen by increasing its variability, thus broadening the host range and allowing the expansion of highly tumorigenic variants.

[Superantigens and murine mammary tumor retrovirus]. / Superantígenos y retrovirus del tumor mamario murino.

Hosts and their pathogens have co-evolved for millions of years, developing multiple and intimate interactions. Vertebrates have evolved a very complex immune system which pathogens have often been able to circumvent, in some cases even managing to appropriate some of its components for their own purpose. Among the pathogens which do use components of the immune system to survive and propagate, those coding for the expression of superantigens (SAgs) are now under intense scrutiny. Investigations concerning one of these pathogens, the mouse mammary tumor virus (MMTV), led to the understanding of how the expression of such components is a critical step in their life cycle. A number of milk-borne exogenous MMTV infect mice shortly after birth and, when expressed, produce superantigens. Herein, we describe the biological effects of new variants of MMTV. Two of these, BALB14 and BALB2 encoding SAgs with V beta 14+ and V beta 2+ specificities, respectively, were present in BALB/c mice of our colony (BALB/cT); a third variant, termed MMTV LA, originated in (BALB/cTxAKR)F1 mice from recombination between BALB 14 and Mtv-7 endogenous provirus. The recombinant LA virus induces the deletion of V beta 6+ and V beta 8.1+ T cells as a consequence of the acquisition of SAg hypervariable coding region of Mtv-7. The SAg encoded by MMTV LA strongly stimulates cognate T cells in vivo leading to a very effective amplification of lymphoid cells in BALB/c mice, correlating with a high incidence of mammary tumors. These results suggest that the presence of non-productive endogenous proviruses--generally considered to confer a selective advantage to the host by protecting it from infection with exogenous MMTVs encoding cross-reactive SAgs--could also be advantageous for the pathogen by increasing its variability, thus broadening the host range and allowing the expansion of highly tumorigenic variants.

Long-lasting functional unresponsiveness induced by a milk-transmitted Mls-1a-like superantigen.

We have recently shown (Piazzon et al. (1994) J. Immunol. 153, 1553) that foster-nursing of BALB/c mice on F1 Mls-1bxa mothers induce the progressive deletion of V beta 6+ and 8.1+ T cells in 50% of the mice. Preceding clonal deletion, a state of functional inactivation of CD4+ T cells to Mls-1a and anti-V beta 6 antibodies was detected in young mice. In the present paper we show that foster-nursing of BALB/c mice on (BALB/cxAKR)FI mothers is able to induce alterations in T cell reactivity in the non-deletor mice. Lymph node cells from foster-nursed mice show a decreased proliferative level against anti-V beta 6 antibodies and a diminished response in MLR and in CTL assays. The proliferative responses to either OVA or Con-A are also reduced. This state of functional inactivation is detected even in 6-month-old foster-nursed mice. Thus, the transmission through milk of the Mls-1a-like superantigen correlates in the non-deletor mice with a long-lasting state of functional inactivation and a decreased immune reactivity.

A maternally-inherited alteration in the T cell repertoire of BALB/c mice.

A number of milk-borne exogenous mammary tumor viruses (MMTV) infect mice shortly after birth and, when expressed, produce superantigens. The expression of these superantigens mediate the progressive deletion of T cells expressing specific V beta products. Here we describe a maternally-inherited alteration in the T cell repertoire in one colony of BALB/c mice which has not been reported up to now. This alteration involves the deletion of V beta 2+ and 14+ CD4+ T cells and correlates with a high incidence of mammary tumors, suggesting the involvement of a superantigen(s) probably transmitted through an exogenous MMTV in milk.

A maternally-inherited alteration in the T cell repertoire of BALB/c mice.

A number of milk-borne exogenous mammary tumor viruses (MMTV) infect mice shortly after birth and, when expressed, produce superantigens. The expression of these superantigens mediate the progressive deletion of T cells expressing specific V beta products. Here we describe a maternally-inherited alteration in the T cell repertoire in one colony of BALB/c mice which has not been reported up to now. This alteration involves the deletion of V beta 2+ and 14+ CD4+ T cells and correlates with a high incidence of mammary tumors, suggesting the involvement of a superantigen(s) probably transmitted through an exogenous MMTV in milk.

Transmission of an Mls-1a-like superantigen to BALB/c mice by foster-nursing on F1 Mls-1bxa mothers. Sex-influenced onset of clonal deletion.

Foster nursing of BALB/c (Mls-1b) mice on (BALB/cxAKR/J)F1 and (BALB/cxDBA/2)F1 (Mls-1bxa), but not on (BALB/cxC57Bl/6)F1 or (BALB/cxC3H/He)F1 (Mls-1bxb mothers, induced the progressive deletion of V beta 6+ and V beta 8.1+ T cells in 50% of the litter. The onset of this Mls-1a-like clonal deletion was markedly sex-influenced, being earlier in females (8-10 wk of age) than in males (32 wk). In both sexes, CD4+ V beta 6+ cells were more affected than CD8+ V beta 6+ cells. Decreases in the percentage of V beta 6+ cells were detected simultaneously in the thymus, lymph nodes, and peripheral blood. Preceding clonal deletion, functional unresponsiveness of CD4+ T cells to Mls-1 a Ags and to anti-V beta 6 Abs could be detected in most young male and female mice. The transmission of the Mls-1a-like superantigen through foster-nursing on (BALB/cxAKR/J)F1 mice correlated with the presence in milk of the mouse mammary tumor virus envelope protein gp52.

Regulation of parental alloreactivity by reciprocal F1 hybrids. The role of lactation.

Adult reciprocal F1 hybrids differ in their susceptibility to parental graft versus host (GvH) reactions. These reactions were lower when the donor strain was syngeneic with the maternal one. Splenocytes from the member of the reciprocal pair in which the GvH reactions were lower also induced a decreased response of parental cells in cytotoxicity assays and in mixed lymphocyte reactions (MLR). The treatment with anti-CD8 plus complement was able to abrogate the different stimulatory ability of the reciprocal F1 spleen populations. Foster-nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their splenocytes to induce both parental anti-F1 MLR and CTL. The stimulatory ability was indistinguishable from that observed in the reciprocal F1 combination nursed on its own mother. Moreover, lactation was able to alter the ability of CD8+ spleen cells to regulate CTL and parental anti-F1 MLR. The results reported herein show the existence of a maternal effect acting though milk capable of altering the regulation of parental alloreactive T reactions towards self histocompatibility antigens.

Neonatal thymic contrasuppressor activity on graft versus host reactions towards self histocompatibility antigens. Parental effects.

The ability of fetal and neonatal F1 thymocytes to regulate parental graft versus host (GvH) reactions against self histocompatibility antigens was investigated. The results obtained showed that: (1) fetal F1 thymocytes were able to suppress both maternal and paternal GvH reactivity; (2) at birth, thymocytes were still able to suppress maternal GvH reactivity while no suppression of paternal reactions was detected; the ability to suppress maternal GvH reactions could be detected until day 3; (3) the loss of suppressor activity correlated with the ability of thymocytes to contrasuppress parental GvH reactions. Thus, 24-h F1 thymocytes showed contrasuppressor activity on paternal GvH reactivity and 4-day thymocytes on maternal reactivity. Thymic cells with contrasuppressor activity were shown to be Lyt-1+, CD4+, CD8- and adherent to Vicia villosa. These results suggest the existence of parental effects influencing the duration of thymic suppression and the subsequent appearance of contrasuppressor activity on GvH reactions against self histocompatibility antigens, according to the maternal or paternal origin of self antigens towards which the reaction is directed.

Popliteal lymph node enlargement induced in syngeneic hosts by T cells from foster-nursed mice.

Splenocytes from adult F1 mice were assayed for their capacity to induce popliteal lymph node enlargement (PLNE) when inoculated in the footpad of identical or reciprocal F1 hosts. The results obtained showed that: (i) T Lyt 1+ splenocytes from adult F1 hybrids were able to induce a significant PLNE when inoculated in reciprocal but not in identical F1 hosts. (ii) Foster-nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their T splenocytes to induce PLNE: Lyt 1+ splenocytes were able to induce significant PLNE in identical but not in reciprocal F1 hosts. Thus, the ability of T splenocytes from foster-nursed F1 hybrids to induce PLNE resembled that observed in reciprocal F1 hybrids nursed by their own mothers. (iii) PLNE was accompanied by cell proliferation involving host B and T lymphocytes. (iv) This PLNE could be detected using F1 hybrids from parental strains differing or not at H-2 antigens but involving a parental strain expressing the stimulatory Mlsa allele and a parental strain bearing the nonstimulatory Mlsb allele while it was not observed in F1 hybrids from parental strains sharing Mlsa antigens.

[Ontogeny of T-cell recognition of self histocompatibility antigens: parenteral influences]. / Ontogenia del reconocimiento T de antígenos de histocompatibilidad propios: influencias parentales.

The existence of parental influences on the recognition of self histocompatibility was investigated. The results obtained showed that: 1) fetal liver and neonatal splenocytes and thymocytes from F1 mice differed in their capacity to regulate parental alloreactive T reactions against self histocompatibility antigens either of maternal or paternal origin. Fetal and neonatal F1 cells--until day 5--were able to suppress systemic and local GvH reactions induced in F1 hosts with maternal but not with paternal splenocytes; 2) this differential regulatory activity concerning parental GvH reactions against self histocompatibility antigens are correlated with the existence of a differential time lag in the appearance of thymic contrasuppressor activity on maternal anti-paternal and paternal anti-maternal GvH reactivity; 3) splenocytes from reciprocal F1 hybrids--from day 14 onwards--differed in their ability to stimulate F1 T cell proliferation in SMLC reactions; 4) foster nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their splenocytes to stimulate the proliferation of responder F1 T cells. The stimulatory ability of splenocytes from foster-nursed hybrids was indistinguishable from that observed in the reciprocal F1 combination nursed by their own mother, suggesting that lactation would be involved in the differences registered; 5) reciprocal F1 mice differed in their response to conventional antigens presented in the context of parental Ia antigens, lactation also being responsible for the induction of these differences. The different mechanisms involved in the alterations of the outcome of self recognition in the litter are discussed.

Ontogenia del reconocimiento T de antígenos de histocompatibilidad propios: influencias parentales. / [Ontogeny of T-cell recognition of self histocompatibility antigens: parenteral influences]

The existence of parental influences on the recognition of self histocompatibility was investigated. The results obtained showed that: 1) fetal liver and neonatal splenocytes and thymocytes from F1 mice differed in their capacity to regulate parental alloreactive T reactions against self histocompatibility antigens either of maternal or paternal origin. Fetal and neonatal F1 cells--until day 5--were able to suppress systemic and local GvH reactions induced in F1 hosts with maternal but not with paternal splenocytes; 2) this differential regulatory activity concerning parental GvH reactions against self histocompatibility antigens are correlated with the existence of a differential time lag in the appearance of thymic contrasuppressor activity on maternal anti-paternal and paternal anti-maternal GvH reactivity; 3) splenocytes from reciprocal F1 hybrids--from day 14 onwards--differed in their ability to stimulate F1 T cell proliferation in SMLC reactions; 4) foster nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their splenocytes to stimulate the proliferation of responder F1 T cells. The stimulatory ability of splenocytes from foster-nursed hybrids was indistinguishable from that observed in the reciprocal F1 combination nursed by their own mother, suggesting that lactation would be involved in the differences registered; 5) reciprocal F1 mice differed in their response to conventional antigens presented in the context of parental Ia antigens, lactation also being responsible for the induction of these differences. The different mechanisms involved in the alterations of the outcome of self recognition in the litter are discussed.

Maternal influence on the immune response: SMLC reactions between identical and reciprocal F1 hybrids and the role of lactation.

Identical and reciprocal adult F1 mice from different strain combinations, either nursed on their own mothers or foster-nursed on mothers from the paternal strain, were used to carry out SMLC assays. The results obtained showed that: (1) in vitro proliferation of F1 T cells was significantly different when splenocytes from identical versus reciprocal hybrids were used as the stimulatory population, splenocytes from one of the members of the reciprocal pair being able to induce higher proliferative responses of T cells from both identical and reciprocal F1 hybrids; (2) foster-nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their splenocytes to stimulate the proliferation of responder F1 T cells. The stimulatory ability of splenocytes from foster-nursed hybrids was indistinguishable from that observed in the reciprocal F1 combination nursed by its own mother. The existence of a maternal effect acting through milk on the outcome of self recognition in the litter is discussed.

Neonatal cells in the immunoregulation of parental alloreactivity.

The ability of neonatal murine F1 cells to regulate parental graft vs. host (GvH) reactions was investigated. Neonatal F1 splenocytes were able to decrease significantly the deleterious effects of systemic GvH reactions induced either with maternal or paternal splenocytes in a third party strain. Both neonatal F1 splenocytes or thymocytes were able to decrease local GvH reactions induced with maternal splenocytes towards paternal histocompatibility antigens. In the same experimental conditions, however, neonatal F1 cells were unable to decrease local GvH reactions induced with paternal splenocytes towards maternal histocompatibility antigens; using different numbers of neonatal F1 cells not only was no suppressive effect detected but even, a significant increase in GvH was registered. Similar results were obtained when mortality assays were carried out. It can be concluded that neonatal F1 mice differ in their capacity for regulating parental alloreactive T reactions against self histocompatibility antigens either of maternal or paternal origin.

Early increase in graft-versus-host reactivity during pregnancy in the mouse.

Alloreactive T levels of para-aortic lymph nodes (PALN) and spleen were determined on different days of pregnancy in BALB/c females by local and systemic graft-versus-host (GvH) assays. A significant increase in GvH reactivity was registered early in both allogeneic and syngeneic matings, operating not only towards paternal but also towards third party strains. Immunoregulatory mechanisms in PALN also involved the appearance of progressive suppression during the first days of pregnancy. The possible role of non-specific early increases in T alloreactivity in triggering suppressor mechanisms and the nature of the immunogens responsible for the alterations in GvH reactivity are discussed.

Maternal immunoregulation: interrelationship between alloreactive and anti-self plus conventional antigen T sets of cells.

In a previous paper we reported early immunoregulatory mechanisms involving not only the appearance of progressive suppression but also significant increases in alloreactive T levels in paraaortic lymph nodes (PALN) and spleen, not only in allogeneic but also in syngeneic pregnancies. Taking into account the hypothesis of the superposition of the alloreactive and the anti-self plus conventional antigens T sets of cells, we investigated whether immunization with conventional antigens was able to alter alloreactive T levels. Weekly i.p. doses of rabbit red bloods cells (RRBC) in BALB/c mice resulted in a dose-dependent increase in spleen alloreactivity as determined by graft-versus-host (GvH) assays in strain combinations differing at H-2 level but not in those sharing the same H-2 with BALB/c. The increases could be significantly decreased by an anti-idiotype anti-RRBC serum. Pretreatment with i.p. weekly doses of sheep red blood cells (SRBC) before mating was able to induce dose-dependent fetal damage when the parents differed at the H-2 level. SRBC immunization in one of the uterine horns induced increases in PALN weight which were much higher in progesterone-pseudopregnant than in virgin mice; T alloreactivity was significantly increased in the draining PALN only in pseudopregnant females. These results favour the postulation of the superposition between the alloreactive and the anti-self plus conventional antigens T sets of cells and suggest a possible role for conventional fetal antigens (non H-2) in triggering immunoregulatory mechanisms operating in pregnancy.