Search PubMed⌕ Search

Biomedical subjects

G Janossy

Publications and source records attributed to G Janossy.

At least 307 records · Page 17Linked to original sources
PubMed1976

Analysis of human leukaemic cells using cell surface binding probes and the fluorescence activated cell sorter.

Cell surface binding fluorescent ligands have been used to distinguish between different types of leukaemic cells and between leukaemic cells and their presumed normal counterparts or progenitors. Binding of these probes was evaluated using the Fluorescence Activated Cell Sorter (FACS) which provides both rapid, objective and quantitative recording of fluorescent signals from individual cells plus physical separation of cells of particular interest. Binding sites for cholera toxin (monosialoganglioside GM1) were found to be normally expressed in chronic leukaemias but greatly diminished or absent in acute leukaemias irrespective of their morphological type. Antibodies specific for the common form of acute lymphoblastic leukaemia (ALL, non-T, non-B) have been produced in rabbits. After extensive absorption and testing these were shown to define a cell surface antigen of non-T, non-B type ALLs. The antigen is absent from other leukaemias with two interesting exceptions--the majority of acute undifferentiated leukaemias express the antigen as do a proportion of chronic granulocytic leukaemias in blast crisis relapse. The anti-ALL antibodies can therefore be used to distinguish different leukaemias and, more significantly, can identify the existence of relatively rare leukaemic cells in the blood of untreated patients and the marrow of treated patients considered to be in remission.

Antibodies, Neoplasm↗
PubMed1976

Lymphocyte activation. VIII. The application of a whole blood test to the quantitative analysis of PHA responsive T cells.

In diluted blood predominantly T cells responded to purified PHA (pure leucoagglutinin Wellcome). Red cells and non-T mononuclear cells increased PHA responsiveness of T cells at concentrations present in the peripheral blood. Addition of polymorphonuclear leucocytes was a very slight further advantage. The incorporation of [3H] thymidine reflected the numbers of T cells in culture, although not perfectly linearly, since counts increased when more T cells were added to the cultures. It was therefore concluded that in cultures of diluted whole blood non-specific amplification mechanisms were provided and responses reflected the performance of stimulated T lymphocytes. Since the method is simple and the number of technical variables is relatively small, it is possible to establish a "normal" range of PHA responsiveness expressed in absolute counts per minute, and thus directly compare results from different laboratories.

Blood↗
PubMed1976

Blast crisis of chronic myeloid leukaemia (CML). I. Presentation simulating acute lymphoid leukaemia (ALL).

Seven patients presenting as an acute leukaemia caused difficulty in diagnosis. The lymphoid appearance of the balst cells either initially or during treatment suggested acute lymphoid leukaemia (ALL). In each case the Philadelphia chromosome was shown to be present thus suggesting that these cases were examples of chronic myeloid leukaemia (CML) presenting in blast crisis without a detectable chronic phase. The implications of these findings are discussed and the difficulty in achieving a precise diagnosis in the acute leukaemias is emphasised. Cytogenetic analysis should be carried out whenever the type of acute leukaemia present is of critical importance.

Adolescent↗
PubMed1976

Blast crisis of chronic myeloid leukaemia (CML). II. Cell surface marker analysis of "lymphoid" and myeloid cases.

Fourteen cases of philadelphia chromosome (Ph1) positive chronic myeloid leukaemia in blast transformation have been investigated using cell surface markers. Morphologically eight cases were lymphoid and the remainder myeloid in appearance. All cases were negative with surface markers for thymocytes and T and B lymphocytes. Five of the lymphoid cases reacted with an antiserum specific for acute lymphoid leukaemia )ALL) of non-T non-B type and were also weakly reactive with a lymphocyte reactive antiserum. A sixth patient, whose blast cells were anti-ALL negative (ALL-) at presentation, subsequently developed central nervous system leukaemia with anti-ALL positive (ALL+) blast cells in the CSF. In all cases the leukaemic blast cells showed greatly diminished expression of cholera toxin receptors when compared to granulocytic cells from the chronic phase of CML. This parallels weak or negligible expression of the cholera toxin receptor in ALL and AML. These results suggest that the blastic phase of CML may involve different cellular derivatives of a pluripotential stem cell in which the primary malignant/genetic changes reside. The blast crisis of CML can therefore be heterogeneous with respect to cellular expression and in a significant proportion of patients involves a cell which is by membrane markers and morphological criteria indistinguishable from that seen in the common form of ALL. In these cases the Philadelphia chromosome may be the only distinguishing cellular characteristic.

Cell Transformation, Neoplastic↗
PubMed1976

Enumeration of polyclonal mitogen-responsive cells in different lymphoid tissues of the mouse.

The relative number of cells capable of responding to Con A, PHA and LPS in the spleen, blood, lymph node and Peyer's patches of CBA mice has been quantified by means of a cytological analysis technique. No difference has been found between Con A- and PHA-responsive cells in spleen and lymph node. The lymphoid tissues of T cell-deprived mice have a reduced content of PHA responsive cells, but LPS responsiveness is within normal limits. Pretreatment of peripheral lymphocyte populations with high concentrations of anti-O antiserum and complement abolishes the response of the treated cells to PHA, but not to LPS, whereas similar treatment with a cytotoxic anti-immunoglobulin serum, which has no effect on PHA-responsive cells, only partially reduces the response to LPS. The results for mitogen responsiveness are discussed with reference to other methods of quantifying T and B cells using cell-surface markers.

Animals↗
PubMed1976

The effects of purified mitogenic proteins (Pa-1 and Pa-2) from pokeweed on human T and B lymphocytes in vitro.

Purified proteins (Pa-1 and Pa-2) from pokeweed have been compared with commercial pokeweed mitogen (PWM-G) and other mitogens in their ability to stimulate human lymphocytes. With cultures of T and B cells separated from tonsil lymphocytes, thymidine uptake, blast transformation and immunoglobulin (Ig) synthesis have been measured. IgM and IgG was measured in supernates of stimulated cultures by radioimmunoassay. Pa-1, Pa-2 and PWM-G were found to be potent mitogens for unseparated tonsil lymphocytes or nylon column purified T cells. Pa-2 was found to be active at lower concentrations than Pa-1, and PWM-G was less potent than the purified mitogens. These three mitogens all stimulated unseparated lymphocytes to secrete large quantities of Ig (20-100 mug/ml) during 7 days in culture. With increasing amounts of mitogens severe decreases in immunoglobulin synthesis were observed at day 6 even with doses which were still optimal for stimulation of thymidine uptake at days 3 and 6. With purified B cells (less than 2% T cells) Pa-1 was the best mitogen for thymidine incorporation. However, the secretory response was very variable. In some experiments B cells did not secrete Ig in response to mitogens; in others Pa-1 was clearly more effective at stimulating secretion than Pa-2 or PWM-G and in some experiments B cells were stimulated by all three. In one experiment Pa-1 stimulated prolymphocytic leukaemia cells to blast transformation and the secretion of IgM. It is concluded that Pa-1, Pa-2 and PWM-G are much better activators of Ig synthesis in human cultures than either PHA or LPS and that Pa-1 is the most reliable B-cell stimulant of the three.

B-Lymphocytes↗
PubMed1976

Patterns of B-lymphocyte gene expression elicited by lipopolysaccharide mitogen.

When large proportions of B lymphocytes from the murine spleen are stimulated in vitro by bacterial lipopolysaccharide (LPS) B lymphoblasts with small amounts of intracellular immunoglobulin (Ig) and plasmablasts with large amounts of intracellular Ig concomitantly proliferate. It is likely that B lymphocytes are heterogeneous and LPS activates B cells to express their predetermined functional capacity since bromodeoxyuridine does not inhibit the initiation of Ig synthesis in plasmablasts, and Ig synthesis starts before these cells complete their first mitosis. The results suggest that LPS is a potent polyclonal activator (of a B-cell subset) but it is not a differentiation factor in the sense that it is unable to determine whether its target cell develops extensive endoplasmic reticulum or follows a different pathway. The results do not exclude that modulation of B cells' genetic programming might take place during T cell-dependent B-lymphocyte activation. The observed B-cell heterogeneity offers a possible explanation for the concomitant emergence of B memory cells and antibody producers during the early phase of immune responses in vivo.

Animals↗
PubMed1975

The immunological properties of haptens coupled to thymus-independent carrier molecules. III. The role of the immunogenicity and mitogenicity of the carrier in the induction of primary IgM anti-hapten responses.

Hapten (DNP-lys) conjugates of two putatively nonimmunogenic polymers, hyalutonic acid and poly-gamma-D-glutamic acid, induce significant primary IgM anti-DNP responses in C3H mice. Preparations of various immunogenic (Type 3 pneumococcal polysaccharide (SIII), levan, E. coli lipopolysaccharide) and nonimmunogenic (hyaluronic acid and poly-glutamic acid) polymers were tested for their ability to act as polyclonal mitogens in vitro. In serum-containing spleen cell cultures, only lipopolysaccharide stimulated substantial cell proliferation. In serum-free medium, and using high specific activity [3H]thymidine, lipopolysaccharide, levan, SIII and to a lesser degree hyaluronic acid induced significant thymidine incorporation. However, under the latter conditions cell survival and proliferation were much less impressive. There was no apparent correlation between the capacity of various polymers to induce lymphocyte proliferation and their "potency" as carriers for the generation of a primary IgM anti-DNP response. Furthermore while low doses of lipopolysaccharide elicited "polyclonal" antibody formation in vivo, high doses of SIII, levan and hyaluronic acid did not. These results indicate that T cell-independent B cell triggering is dependent on the polymeric nature of the antigen, and that polymers need not be immunogenic or mitogenic to act as carriers for the induction of primary IgM anti-hapten antibody responses.

Animals↗
PubMed1974

Selective triggering of human T and B lymphocytes in vitro by polyclonal mitogens.

Human lymphocytes from spleen and tonsils have been cultured with a variety of polyclonal mitogens. Cultures consisted of either unseparated T and B cells or alternatively purified T or B lymphocytes. The purity of the starting cell populations and the origin of activated lymphoblasts was analyzed with a panel of seven markers which discriminate between T and B cells. The selectivity of the lymphocyte responses was influenced by cell populations in a given culture, the mitogen used, and to a limited extent on culture conditions. Purified T lymphocytes from tonsil and spleen responded to phytohemagglutinin (PHA), pokeweed mitogen (PWM), and staphylococcal enterotoxin B (SEB). Purified B cells from spleen responded well to PWM, weakly to SEB and lipopolysaccharide, but not at all to PHA. Tonsil B cells responded weakly to PWM and SEB but not to PHA. Some B lymphocytes do respond to PHA in the presence of activated T cells. These results are discussed in relation to previously reported selective responses of human cells and parallel studies in animal species.

B-Lymphocytes↗