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J R Head

Publications and source records attributed to J R Head.

At least 37 records · Page 2Linked to original sources
PubMed1989

Murine trophoblast can be killed by lymphokine-activated killer cells.

The ability of fetal trophoblast cells in the placenta to resist cell-mediated lysis may be important for successful pregnancy. Previous studies in this laboratory demonstrated that cultured midterm mouse trophoblast cells are not susceptible to allospecific CTL generated by standard in vitro protocols, to antibody-dependent cell-mediated cytotoxicity, or to naive or IFN-activated NK cells, despite expressing the requisite target structures. However, we now report that murine trophoblast can be killed, in a non-MHC-specific manner, by LAK cells. Normal mouse spleen cells cultured for 4 days in IL-2-containing lymphokine preparations characteristically killed both NK-sensitive (YAC-1) and NK-resistant (EL4, P815) target cells, and mediated significant lysis of both cultured and freshly isolated trophoblast cells (35 to 55%, E/T 100/1). Pretreatment of the LAK cells with anti-ASGM1 antibody and C markedly reduced the lysis of trophoblast and YAC-1 targets, suggesting that the responsible cells belonged to the NK lineage. The ability of IL-2-activated NK cells to kill midterm murine trophoblast cells was confirmed using a population of highly lytic NK cells generated by culturing spleen cells from severe combined immunodeficiency mice in 500 U/ml rIL-2 for 5 days. These effector cells killed YAC-1, EL4 and P815 target cells at much lower E/T ratios than was achieved with the normal splenic LAK cells, and mediated significant lysis of both freshly isolated (45 to 50%, E/T 20/1) and cultured trophoblast cells (68 to 76%, E/T 20/1). The susceptibility of trophoblast to LAK cells and IL-2-activated NK cells supports the need for suppressor mechanisms regulating IL-2 activity at the maternal-fetal interface.

Animals↗
PubMed1989

Differential expression of the class I MHC genes in the embryo and placenta during midgestational development in the mouse.

A sensitive RNase mapping technique was used to investigate the expression of individual class I mRNA in the embryo and placenta of the mouse from day 7.5 through day 13 of gestation. Transcripts of the H-2Kd and -Dd genes appeared in both placental and embryonic tissues as early as day 7.5 post coitum and continued to be expressed thereafter. In contrast, H-2Ld mRNA was barely detectable in embryonic RNA until day 18 of pregnancy, although it was present in placental RNA samples on days 10 to 13 of gestation. Qa-region genes demonstrated a different pattern of expression than H-2Dd, -Kd, and -Ld. Transcripts of Q7, one of the genes encoding Qa-2 surface Ag, were detected in the developing embryo on days 9 to 11 post coitum but decreased thereafter. However, Q7d transcripts were not detected in placental tissues at any stage. Q6 mRNA was not detected in any of the tissues, and Q10 mRNA was detected only in day 12 to 13 embryos, where expression is known to be restricted to the fetal liver. Transcripts from T13, a Tla-region gene, and D2d, a D-region gene, were not detected in any of the samples tested. This study has revealed a complex pattern of class I gene regulation both within the genes of the MHC and between the embryo and placental lineages during the midgestational stages of development.

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PubMed1989

Murine trophoblast can be killed by allospecific cytotoxic T lymphocytes generated in GIBCO Opti-MEM medium.

Previous work in this laboratory demonstrated that a population of cultured midterm murine trophoblast cells are not susceptible to lysis by allospecific cytotoxic T lymphocytes (CTL) generated by standard in vitro protocols. We now report that this trophoblast population is killed, in an MHC-dependent manner, by allospecific CTL generated in GIBCO Opti-MEM, a modified tissue culture medium designed to maintain cell growth and proliferation in the presence of low concentrations of fetal bovine serum (FBS).

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PubMed1988

Murine trophoblast resists cell-mediated lysis. II. Resistance to natural cell-mediated cytotoxicity.

The susceptibility of murine trophoblast cells to natural cell-mediated cytotoxicity has been assessed. Primary short-term cultures of murine trophoblast cells isolated from 14-day placentas were found to be resistant to endogenous and interferon-activated natural killer (NK) cells and natural cytotoxic cells. That the relevant target structures are expressed on the surface of trophoblast cells and accessible to the effectors was demonstrated by their ability to inhibit the lysis of NK-sensitive target cells (YAC-1) in a dose-dependent manner. The lytic resistance of trophoblast cells was unaffected by neuraminidase treatment, inhibition of protein synthesis, or extending the assay time to 12 hr. Moreover, trophoblast cells were resistant to antibody-dependent cell-mediated cytotoxicity when coated with an alloantibody capable of mediating their lysis in the presence of heterologous complement. Neither the preincubation of effector cells in concentrated trophoblast culture supernatants nor the direct exposure of effectors to monolayers of trophoblast cells inhibited their NK lytic activity, indicating that the secretion of a suppressive factor or the direct inactivation of the NK cells was not responsible for the observed resistance to lysis. These observations, together with previous results showing the resistance of trophoblast to cytotoxic T cell-mediated lysis, reveal that murine trophoblast cells possess a resistance mechanism against several forms of cell-mediated lysis. This feature of trophoblast cells at the maternal-fetal interface is likely to play an important role in protecting the fetoplacental allograft from immune rejection.

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PubMed1987

Murine trophoblast resists cell-mediated lysis. I. Resistance to allospecific cytotoxic T lymphocytes.

Research on the mechanisms of nonrejection of the fetoplacental allograft has focused on the tissues composing the fetomaternal interface, of which the placental trophoblast, the tissue directly confronting the maternal environment, is considered a prime candidate responsible for the survival of the fetus. We recently developed a method for isolating murine trophoblast, and found that a proportion of trophoblast cells from mature placentas, cultured for 2 days, express class I antigens on their surface, and this expression can be enhanced in vitro by interferon-alpha/beta (IFN-alpha/beta). In the present study, it was determined that cultured trophoblast cells from day 14 placentas were resistant to allospecific cytotoxic T lymphocytes (allo-CTL), while being susceptible to alloantibody and complement-mediated lysis. The trophoblast cells remained resistant to allo-CTL-mediated lysis despite IFN-mediated enhanced expression of class I H-2 antigens on their surface and the addition of phytohemagglutinin into the assay. Inhibition of protein synthesis also had no effect. In contrast, fetal fibroblasts, isolated from the same conceptuses, were readily susceptible to allo-CTL-mediated lysis. That the trophoblast cells do interact with the effector cells was shown by their ability to specifically inhibit the lysis of tumor target cells in a dose-dependent manner. Additionally, trophoblast culture supernatants did not inhibit the lytic activity of allo-CTL, even when concentrated 10- to 25-fold, indicating that a soluble suppressor factor was not inactivating the effector cells. These results suggest that trophoblast cells have a protein synthesis-independent mechanism of resistance to lysis by allo-CTL, which could play an important role in protecting the fetoplacental allograft from maternal immune rejection.

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PubMed1987

Uptake of lymphocytes fed to suckling rats. An autoradiographic study of the transit of labeled cells through the neonatal gastric mucosa.

To determine the potential for transfer of maternal lymphocytes to the newborn during suckling, radiolabeled cells were fed to rat neonates of different ages and autoradiographs prepared from tissue sections obtained from the stomach and small intestine. The entire stomach (including contents) and intestinal walls were observed using semiserial 3 micron methacrylate plastic sections. For these studies 100 X 10(6) [3H]uridine-labeled lymph node cells were fed to 1-4-day-old neonates using a smooth-tipped intubation needle. Some of the lactating female rats had been given radioisotope prior to delivery and "cold" babies were fostered to them to enhance the number of labeled cells in the neonatal digestive tract. Babies were killed at 1, 2, 4, 8, 24 and 48 h after feeding. The stomach contents showed a considerable number of labeled cells (32% at 1 h after feeding) and many of these cells were in close proximity to the epithelium. The gastric epithelium often exhibited gaps between adjacent epithelial cells similar to those we have previously reported in the lactating mammary epithelium, and labeled cells were observed in the immediate area of the gaps. Labeled cells were seen in the neonatal gastric epithelium, lamina propria, mesenteric attachments, in the wall and lumen of small gastric blood vessels and adjacent lymph nodes. Labeled cells were most abundant in the gastric wall at 1-2 h following feeding, indicating that transit through the epithelium occurred rapidly. Although labeled cells were seen in the lumen of the small intestine, none were observed in the tissues of the intestinal wall. When heat-killed labeled cells were fed, no labeled cells were seen in the tissues of the neonatal gastrointestinal tract. It is apparent from these studies that a portion of the leukocytes that are delivered to the neonate during suckling are able to transit the gastric epithelium and establish themselves in the neonate's tissues, presumably to aid in the protection of the immunologically naive infant.

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PubMed1987

Major histocompatibility antigens on trophoblast and their regulation: implications in the maternal-fetal relationship.

Recent technological advances have provided methods of detecting antigens encoded by the major histocompatibility complex with greater precision, allowing the expression of such antigens on the components of the placenta to be clarified. Of specific interest is the expression of these antigens on trophoblast cells, the fetal-derived epithelial cells that confront maternal blood and tissues at the maternal-fetal interface. It is now clear that the different trophoblast subpopulations differentially express class I antigens, although none appear to express class II antigens. Class I antigens can be induced by exposure to interferons on some populations but apparently not others, suggesting that the regulation of their expression differs for subpopulations of trophoblast cells, depending on gestational stage and location. This restricted expression has important implications for maternal-fetal immune interactions during the different phases of pregnancy and perhaps also bears on physiological functions of the feto-placental unit, such as growth and differentiation.

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PubMed1986

Expression of MHC antigens on murine trophoblast and their modulation by interferon.

Primary cultures of defined populations of mouse trophoblast, isolated from mature placentas, were analyzed for their MHC antigen expression and for the modulatory effect of interferon (IFN) by antibody- and complement-mediated cytotoxicity and flow cytofluorometry. The cells were obtained from placentas by enzymatic digestion, followed by Percoll gradient fractionation, and are large, fetally derived epithelial cells, which we previously characterized and identified as trophoblast cells. After 2 days in culture, a significant proportion of the trophoblast cells were susceptible to antibody- and complement-mediated lysis by anti-paternal strain alloantisera (40%) and, to a lesser degree, by an anti-class I monoclonal antibody (20%). Flow cytofluorometric analysis indicated that 20 to 50% of the cultured trophoblast cells expressed low levels of paternal strain class I antigens as compared to L cell fibroblasts. After culture for 48 hr with IFN-alpha/beta or IFN-gamma, the percent of class I-positive cells was increased to 68 to 76%, as was the mean fluorescence intensity, which correlated with the increased percent of antibody- and complement-mediated specific lysis (73%). No expression of class II MHC antigen by the cultured trophoblast cells was detected, even after culture in the presence of IFN-gamma. The cultured trophoblast cells, when tested for alkaline phosphatase (AP) activity, were composed of strongly positive and weakly positive subpopulations. An inverse correlation between strength of AP activity and the expression of H-2 was observed by double staining. These results indicate that trophoblast cells cultured in vitro are able to express paternal strain class I but not class II MHC antigens, as has been reported in vivo, and that this expression can be modulated by IFN. Further study of these cells should provide important clues for the understanding of materno-fetal coexistence in the face of MHC antigen differences.

Alkaline Phosphatase↗
PubMed1986

Ia antigen expression in the rat uterus.

Using indirect immunofluorescence and monoclonal antibodies, we have determined the distribution of Ia+ cells in the non-pregnant rat uterus. In cycling animals, Ia+ cells, most of dendritic shape and non-specific esterase negative, were abundant in the connective tissue of the myometrium and throughout the endometrium, especially adjacent to the luminal and glandular epithelia. In contrast, the number of T lymphocytes was very much less and few of these cells expressed Ia antigen. Stromal Ia+ cells were more numerous during estrus than in any other phase of the cycle. Only a few Ia+ cells were seen in neonatal uterine samples, but the numbers increased to approximately adult levels by 32 days of age. Prepubertal glands were consistently negative, but epithelial expression of Ia antigens in adult uteri showed interesting variations. The luminal epithelium was always negative, whereas the glandular epithelial cells often were positive. Glandular staining was quite heterogeneous in individual samples, but most gland profiles were negative or weakly positive during proestrus and estrus and positive during diestrus. Ovariectomized females given different steroid supplements revealed significant hormonal effects. Estrogen alone dramatically increased the numbers of Ia+ stromal cells compared with control samples, but progesterone alone had no effect. However, progesterone given with estrogen abrogated the estrogenic influence. Progesterone alone caused decreased expression of Ia antigens by the glandular epithelium. If the highly-Ia/ cells in the stroma are capable of antigen presentation, these results indicate a significant potential for local antigen processing with the uterine endometrium.

Animals↗
PubMed1986

Concerning the immunology of the uterus.

As a mucosal organ, the uterus is unique in being subject to exposure to three types of antigen: chronically to micro-organisms, episodically to sperm bearing both auto- and alloantigens as well as soluble antigens in seminal plasma, and to conceptuses--nature's allografts--expressing transplantation antigens. That the uterus is effective in handling pathogens is evidenced by the rarity of infections. Local macrophages, immunocytes, and a secretory immune system, most evident in the cervix, probably underlie this attribute. Mammals' reproductive success hints that the uterus is immunologically discriminating toward the nonharmful but biologically important antigens of classes 2 and 3. Why sperm are not normally destroyed immunologically in the female prior to fertilization and why conceptuses are not rejected are central unresolved questions in reproductive immunology. Undoubtedly, important immunoregulatory principles are operating in this remarkable organ and its decidua. Better to understand antigenic exposure in the rat uterus, we have reinvestigated its lymphatic drainage using labeled cell injection and microanatomical procedures. Despite abundant lymphatics in the myometrium, cells placed in the uterine lumen did not readily gain access to the lymphatic system. There was a paucity of lymphatics in the endometrium, but Ia-positive dendritic cells were abundant. Soluble antigen exposure via the uterus failed to evoke a primary antibody response yet did prime the host for a secondary response. This restriction of systemic antigen presentation from the uterus, in conjunction with both cellular and noncellular immunoregulatory principles acting locally, may be important to ensure maternal hyporesponsiveness to paternal alloantigens.

Animals↗
PubMed1986

Recipient treatment to overcome the allograft reaction, with special reference to nature's own solution.

The 6th decade of this century was particularly important for transplantation immunology. The universality of allograft rejection by normal hosts had won general acceptance and, experimentally, several means of abrogating host reactivity to allografts were discovered. These included sub-lethal whole body irradiation, administration of certain corticosteroid hormones and inoculation of very young animals with living cellular inocula from the future graft donor--i.e., classic, neonatal tolerance. The latter was particularly important since it indicated the feasibility of a specific, permanent solution to the clinical allograft problem. Radiation and drug-induced tolerance in adult subjects came along and chemical immunosuppressants, which led to successful clinical use of azathioprine. The important rediscovery of ALS pointed towards the development and clinical application of monoclonal antibodies many years later. With the development of immunogenetics and transplantation biology came recognition that the conceptus is a highly successful allograft, raising the question of how it is able to withstand rejection by its immunocompetent mother for the duration of pregnancy. Hopefully, knowledge of the principle(s) involved when they are finally elucidated will be applicable to clinical allograft recipients. Although functional hypoantigenicity of the syncytial trophoblast probably plays a major role in protecting the allogeneic conceptus, a strong case now exists that local, cell-based, immunosuppressive and immunoprotective activity within the placenta and decidua, mediated by suppressor and other cells, is important.

Animals↗
PubMed1985

Functional capacity of solid tissue transplants in the brain: evidence for immunological privilege.

The capacity of the mammalian brain to support the physiological function of allografts was assessed in parathyroidectomized Fischer strain rats bearing either isografts or immunogenic DA allografts of parathyroid glands implanted in their cerebral cortices. Established isografts and allografts survived indefinitely in the brain, maintaining normal serum calcium levels, with equal numbers of spontaneous failures (18-21%) in each group. Similarly, both MHC-compatible and incompatible skin allografts survived and were 'functional' at 40-50 days postgrafting as assessed by: continued formation of keratin; the presence of differentiated hair follicles and sebaceous glands; and frequent mitotic figures. No serum alloantibodies were induced by either MHC-incompatible parathyroid glands or skin in this site. However, both types of allografts were promptly rejected or failed to become established in the brains of specifically presensitized hosts. Furthermore, when Fischer hosts with long-established intracerebral DA parathyroid grafts received orthotopic DA skin grafts, their parathyroid grafts were rejected along with first-set rejection of the skin grafts. The tempo of this cellular immune response and the primary alloantibody response that accompanied it indicate that although the intracerebral grafts failed to induce detectable host sensitization or suppression, they remained susceptible to immune effectors. Thus, by using strongly immunogenic, adult tissues, we have established that the rat cerebral cortex is an immunologically privileged site, and the privilege is not dependent on lack of graft immunogenicity or alterations in host responsiveness. Furthermore, Ia+ (possible antigen-presenting) cells were rare in the cortical parenchyma sites used for transplantation though numerous in the choroid plexus of the ventricles and in certain areas of white matter. Therefore, privilege probably reflects deficient graft antigen presentation related to the paucity of Ia+ cells as well as to the brain's poor lymphatic drainage.

Animals↗
PubMed1985

Migration of radiolabeled, adoptively transferred T-lymphocytes into the mammary gland and milk of lactating rats.

The maternal component in the transfer of cellular immunity from the mother to the neonate during lactation was investigated by analyzing the migration of adoptively transferred T-lymphocytes to the mammary gland and into the milk of lactating rats. A T-enriched cell population, containing less than 2.5% of contaminating B-cells, was obtained from mesenteric and peripheral lymph node cells of donor rats by removing B-cells with a panning technique. The T-enriched cells, radiolabeled with [3H]uridine, were injected intravenously into syngeneic lactating females, between 1 and 4 days post-partum. Samples of mesenteric and cervical lymph nodes, spleen, Peyer's patches, small intestine, and mammary gland taken at 48 h and milk obtained at 24 and 48 h were processed for scintillation counting and autoradiography. A large portion of the injected T-cells migrated to T-dependent lymphoid areas (the paracortical and medullary regions of the mesenteric and cervical lymph nodes and the Peyer's patches) and a substantial number also migrated into the small intestine and mammary gland, although the frequency of cells per high-power field was lower than in the lymph nodes. However, total counts of activity recovered were significantly higher in the small intestine and mammary gland than in either the mesenteric or cervical groups of lymph nodes. The distribution of the T-cells within the mammary gland showed a relative predominance of labeled cells in the connective tissue adjacent to the alveolar secretory cells, with a small percentage of cells present within the mammary epithelium. The direct transfer of T-cells through the alveolar epithelium was demonstrated by the presence of labeled cells in milk. These results substantiate that a significant number of T-lymphocytes migrate not only to the mammary gland during lactation but also into milk. These cells may play a passive regulatory or inductive role within the mammary gland or an active role in the maternal-to-neonatal transfer of immunity.

Animals↗
PubMed1985

Reaction of the chromatoid body with a monoclonal antibody to a rat histocompatibility antigen.

The monoclonal antibody OX3 against a polymorphic class II antigen encoded by the major histocompatibility locus of the rat has been shown to cross-react with the chromatoid body during spermatogenesis. Using an indirect immunofluorescence assay on frozen, fixed testis sections, the antibody revealed a pattern of fluorescent speckling that correlated with specific stages of spermatogenesis. The positive material first appeared in late pachytene spermatocytes as multiple small spots. Larger dots appeared in all regions containing round spermatids, but, as the spermatids matured, only fine dots were seen. Mature spermatids were negative, as were all early cells (spermatogonia to early pachytene spermatocytes). When suspension of fixed testicular cells were tested, the activity was clearly associated with the chromatoid body adjacent to the nucleus in round spermatids and with multiple smaller structures encircling the nucleus in primary spermatocytes. These associations were confirmed in observations on immature testes at various ages. No reactivity was seen in testes of animals whose testes had previously been irradiated to render them aspermatogenic, nor in grc/grc rats in which spermatogenesis is arrested at the primary spermatocyte stage. Because the expression of this reactivity was seen even in rats that do not express the OX3 antigen on their somatic cells, this antibody should prove useful in determining the structure of this body, its origin and fate, and any possible role it may have in spermiogenesis.

Animals↗
PubMed1985

Immune privilege in the testis. II. Evaluation of potential local factors.

The significance of several local factors in prolonging allograft survival in the rat testis has been investigated. The lower temperature of this organ was shown to have no effect, because parathyroid gland allografts implanted s.c. in the ear, which is similarly hypothermic, were rejected as promptly as in conventional sites. Conversely, testes secured in the abdominal cavity afforded privilege to grafts just as well as normal testes. With indirect immunofluorescence using a monoclonal antibody, it was shown that the testis' interstitial tissue is well-endowed with cells bearing class II histocompatibility antigens, a prerequisite for antigen-processing capability. When intratesticular allograft recipients were pretreated with estrogen to suppress Leydig cell synthesis of testosterone, most grafts were rejected promptly, suggesting that local steroid secretion is important in testicular immune privilege. Both testes and s.c. sites supported inflammatory reactions to cotton pledgets, indicating that there is no interference with the nonspecific inflammatory process necessary for graft rejection, but more likely with antigen processing itself.

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