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K W Pyke

Publications and source records attributed to K W Pyke.

18 recordsLinked to original sources
PubMed1986

In vitro colonization of thymic primordia by adult bone marrow cells: light scatter profile and separation by flow cytometry.

Adult mouse bone marrow showed a reproducible scatter profile on low angle vs. right angle scatter by flow cytometry and it was possible to sort cells from different regions of the profile. The colonization of the third pharyngeal pouch in vitro was used as a test of thymocyte precursors. Alleles of the Thy-1 surface antigen, as well as the nuclear chromatin pattern of the ichthyosis mutant, were used to monitor chimerism. Thymus-colonizing cells were found in one region of the scatter profile, and these cells were negative for Thy-1 and Ia markers.

Animals↗
PubMed1985

Murine fetal colon in vitro: assays for growth factors.

The growth of murine fetal colon was examined in two tissue-culture systems: an organ-culture assay and a modified Hamburger assay for the production of cell colonies in a semi-solid medium. The organ-culture system was found to support the normal development of the intact colon for several weeks, but epithelium separated from mesenchyme produced terminal squamous differentiation within 1 week. Gastrin analogues permitted continued growth of the epithelium, but produced a maturation arrest which was reversible by the removal of the hormone and after prolonged culture. Epidermal growth factor (EGF) produced some mesenchymal proliferation but, as with the other reagents tested, had no effect on the epithelium in organ culture. Analogues of gastrin produced enhanced colony formation in cells from fetal colon and neonatal colon obtained up to 2 weeks post-partum, but had no effect on adult colon. No enhanced colony formation was seen with EGF, oestrogen, dexamethasone, indomethacin, progesterone, prolactin and testosterone. Mouse fetal colon in organ culture can be a useful model for screening possible trophic factors for the colon in a qualitative way, while the colony-assay system can be used to provide quantitative results.

Aging↗
PubMed1985

Thymic microenvironmental factor: a possible chemoattractant for hemopoietic stem cells.

A thymic microenvironmental factor (TMF), distinct from thymic epithelial supernatant, was extracted from membranes of thymic stromal cells. Using a migration-under-agar assay, we showed that hematopoietic stem cells from fetal liver could migrate specifically towards TMF. Fetal thymic rudiments, which are known to attract such cells, can compete for TMF activity in this test. An antibody to TMF inhibited TMF activity. Bone marrow cells and peritoneal macrophages were not specifically attracted towards TMF. We also showed that TMF-attracted cells can colonize embryonic thymic rudiments.

Animals↗
PubMed1984

Thymic sensitivity to sex hormones develops post-natally; an in vivo and an in vitro study.

In vitro thymic organ cultures were used to examine the effects of the sex hormones estradiol and dihydrotestosterone on thymocytes. In contrast with the marked loss of cortical thymocytes seen in vivo with these hormones, no effect was apparent in vitro even at concentrations up to 10(-6) M. The glucocorticoid dexamethasone caused severe depletion in vivo and in vitro. Thymic androgen and estrogen receptors were determined; in the newborn animals up to 2 wk of age, receptor levels were barely detectable. The possibility of indirect modulation of thymic function by steroids in vivo was investigated by culturing thymic lobes in media containing serum from animals treated with these hormones. Only sera from dexamethasone-injected animals caused changes in cell size, number, viability, or phenotype in the culture system. The mechanism for the previously reported effects of sex steroids on the neonatal thymus therefore remains to be elucidated.

Aging↗
PubMed1983

The in vitro production of chimeric murine thymus from nonlymphoid embryonic precursors.

A simplified technique for the production of chimeric thymus completely in vitro from the third pharyngeal pouch (TPP) of 10-day mouse embryos has been examined. The results are similar to those obtained by a more cumbersome technique published by others. This modified technique permits the production of large numbers of synchronized chimeric thymuses, so that sufficient numbers of thymocytes are available for multiple functional assays. TPP may also be maintained in culture, then grafted into normal or thymectomized, irradiated, fetal liver-reconstituted hosts where they undergo development into histologically normal lymphoid thymic tissue.

Animals↗
PubMed1983

Functional clonal deletion of cytotoxic T-lymphocyte precursors in chimeric thymus produced in vitro from embryonic Anlagen.

Chimeric thymus, formed by fusing the prelymphoid third pharyngeal pouches of fetal mice with fetal liver, have been allowed to develop entirely in vitro. Syngeneic and allogeneic chimeras were prepared and both types of thymus were shown to contain substantial numbers of functional cytotoxic T lymphocyte precursors reactive against "third party" alloantigens. However, alloreactivity specific for H-2 antigens present on either the third pharyngeal pouch or the fetal liver was minimal. In three different allogeneic chimeric thymuses, the frequencies of cytotoxic T lymphocyte precursors reactive to H-2 antigens present on the third pharyngeal pouches were reduced to 1%, 4%, and 0% of control values, whereas, in the one allogeneic chimera tested for alloreactivity to H-2 antigens present on the fetal liver, the cytotoxic T lymphocyte precursor frequency was reduced to less than 1% of control values. The phenotype of the H-2 tolerance is shown to be one of functional clonal deletion of the cytotoxic T lymphocyte precursor.

Animals↗
PubMed1983

Lymphocyte depletion of murine fetal thymus and subsequent chimeric recolonization in vitro.

Thymus from 14-day murine fetuses, maintained in organ culture, was depleted of lymphocytes when incubated for 7 days at room temperature (24 degrees C) in a gas mixture of 10% CO2 in air or 10% CO2 in O2. Shorter incubation resulted in sparing of some lymphocytes and/or their precursor populations. Cultures grown in CO2 in air maintained their Ia-positive cell population, as demonstrated in single cell suspensions, while those grown in CO2 and O2 appeared to lose Ia-positive cells. When recolonized by fetal liver (FL) the thymuses became fully lymphoid again in organ culture. Depending on the degree of lymphocyte depletion, split chimerism at various levels could be produced, when the FL used was from a strain allogeneic to the thymus.

Animals↗
PubMed1981

In vitro migration of potential hemopoietic precursors from the murine fetus.

An in vitro migration system demonstrated the presence in murine fetal tissues of cells that migrate to thymus, spleen or lymph node. Preincubation of these cells with facteur thymique sérique, a factor derived from the thymus, produced changes in the migration patterns, suggesting a maturation sequence in fetal hemopoietic precursor-cell migration capacity, with migration to the thymus as the initial potential homing target, followed in order by a potential to migrate to the spleen, than to lymph-node tissue.

Animals↗
PubMed1979

The in vitro migration of murine fetal liver cells to thymic rudiments.

The migration of murine fetal liver cells to thymus rudiments was studied in vitro using a migration under agar technique. There appeared to be a minor population that migrated specifically to the thymus from the age of 10 to 14 days of gestation. The specificity of migration was demonstrated in 12-day fetal liver cells by a series of competition studies. The ability of these cells to colonize a thymus rudiment was shown by further incubation after invasion of the epithelial thymus rudiments: small colonies of lymphoid cells were present in invaded tissue but absent from uninvaded control tissue. At 13 to 14 days of gestation, there appeared an additional population that migrated specifically to the spleen, as demonstrated, again, with a competition protocol. Studies with avian and human tissue as attractants in the same system showed that migration was specific to the thymus and did cross species barriers. This observation was used to demonstrate a similar attractant activity in cell-free conditioned medium from human thymus epithelial cultures, and to demonstrate the absence of such a cell-attractant factor in the conditioned medium from the thymus of a child with previously documented severe combined immunodeficiency disease.

Animals↗
PubMed1976

Human thymus/leukemia-associated antigen in normal and leukemic cells.

A saline extractable human thymus/leukemia-associated antigen (HThy-L) has been detected in immunodiffusion using rabbit antisera raised to human thymus extracts. HThy-L was demonstrated in extracts of normal thymocytes, lymphocytes from E-rosetting T-cell lines and from the blast cells of patients with E-rosetting acute lymphoblastic leukemia. Extracts of leukemic cells from patients with acute myeloblastic leukemia and E-rosette-negative acute lymphoblastic leukemia contained significantly lower quantities of HThy-L. Only trace amounts of the antigen were detected in normal spleen tonsil, peripheral blood, bone marrow and PHA-induced lymphoblasts. HThy-L appears to be an antigen associated with the intrathymic differentiation of human T cells and a marker of leukemic cells in certain forms of acute leukemia.

Antigens, Neoplasm↗
PubMed1976

Detection of T-precursor cells in human bone marrow and foetal liver.

Human lymphoid cells that have been incubated with conditioned medium from confluent monolayers of human thymic epithelium (HTCM) show an increase in cells forming rosettes with sheep erythrocytes at 4 degrees C (E-rosettes). Those cells demonstrating this in vitro conversion have been interpreted to be T-cell precursors. Separation of human bone marrow cells on discontinuous bovine serum albumin (BSA) gradients, and on a single-step 23% BSA gradient showed enrichment of these T-precursor cells, not only in bone marrow, but also in human foetal liver cells. Bone marrow precursor cells from a patient with Wiskott-Aldrich syndrome (T-cell deficiency) showed a normal in vitro response to HTCM, but no response was seen in cells from a patient with severe combined immunodeficiency disease.

Agammaglobulinemia↗
PubMed1975

Demonstration of an intrathymic defect in a case of severe combined immunodeficiency disease.

An in vitro system has been developed to elucidate the nature of the cellular defect in primary immunodeficiency diseases. Incubation, on human thymic epithelial monolayer cultures, of peripheral blood lymphocytes and bone-marrow cells from a child with documented severe combined immunodeficiency disease resulted in the appearance of a population of cells that formed rosettes with sheep erythrocytes. The same cell preparation permitted the synthesis of antigen-specific, complement-dependent antibodies after in vitro education, as demonstrated in a plaque assay system. In addition, thymic tissue from the same child gave morphologic and functional evidence of maturation when cultured in vitro. The experimental results suggest that in this case, lymphoid precursor cells were present in the bone marrow but failed to differentiate to functional maturity due to a defect in maturation of thymic tissue.

B-Lymphocytes↗
PubMed1975

Isolation and characterization of the sheep erythrocyte receptor in man.

Properties of the sheep erythrocyte receptor on human lymphocytes were examined from two different aspects: inhibition of E-rosette formation by antisera, and extraction of T and non-T cells with 3 M KCl. Antisera to several T cell populations produced significant inhibition of E-rosette formation by human peripheral blood lymphocytes, whereas anti-B cell, anti-beta2-microglobulin, anti-I, and anit-i were ineffective. Sera with activity to HL-A subgroups on the HPBL tested produced complete rosette inhibition, although nonspecific anti-HL-A produced no inhibition. T cell preparations extracted by a 3M KCl technique contained activity that could be bound to SRBC and produce inhibition of rosette formation by HPBL. This inhibitory component could be quickly eluted from the SRBC and retain its inhibitory activity. No inhibitory activity could be demonstrated in extracts of B cells and non-lymphoid cells. These results suggest that 1) T cell-specific and HL-A specific antisera inhibit E-rosette formation; 2) beta2-M is not involved in the SRBC receptor as an active component; and 3) the receptor may be isolated by 3 M KCl extraction, and partially purified by the use of SRBC as a specific immunoadsorbent, without loss of biologic activity.

Animals↗