scholarly journals The modulation of lymphocyte functions by molecules secreted by macrophages. II. Conditions leading to increased secretion.

1976 ◽  
Vol 144 (1) ◽  
pp. 155-166 ◽  
Author(s):  
E R Unanue ◽  
J M Kiely ◽  
J Calderon
Keyword(s):  
Dna Synthesis ◽  
B Cell Differentiation ◽  
Spleen Cells ◽  
First Case ◽  
Antibody Formation In Vitro ◽  
Increased Activity ◽  
Striking Effect ◽  
Antibody Secreting Cells ◽  
Stimulation Of

Cultures of peritoneal exudate cells rich in macrophages were studied for the secretion of lymphostimulatory molecules. Two conditions produced increased secretion: (a) addition to the cultures of various agents that readily interacted with macrophages, such as latex particles, antibody-coated red cells, endotoxin, Listeria organisms, or Be salt; or (b) addition of activated lymphocytes. In the first case the increased activity was found during the first 24 or 48 h after uptake of the stimuli. Increased activity was found in normal or peptone-stimulated macrophages but not in macrophages after injection of endotoxin or thioglycollate. The addition of T lymphocytes from Listeria-infected mice to macrophage cultures increased greatly the activities. This increase was also produced by addition to antigen-primed T cells together with antigen. The lymphocytes by themselves did not secrete active factors. The lymphostimulatory activities were tested on thymocyte DNA synthesis and on antibody formation in vitro. The latter assay was done on spleen cells from immunized mice where one striking effect was the stimulation of differentiation to antibody-secreting cells. Some dissociation of both activities (thymocyte DNA synthesis and B-cell differentiation) was observed with selected culture fluids.

scholarly journals Primary generation of cytolytic T lymphocytes in the absence of DNA synthesis.

1979 ◽  
Vol 150 (1) ◽  
pp. 196-201 ◽  
Author(s):  
H R MacDonald ◽  
R K Less
Keyword(s):  
T Lymphocytes ◽  
Dna Synthesis ◽  
Cytolytic Activity ◽  
Target Cells ◽  
Cytolytic T Lymphocytes ◽  
Spleen Cells ◽  
Con A ◽  
A Cell ◽  
Stimulation Of

The requirement for DNA synthesis during the primary differentiation of cytolytic T lymphocytes (CTL) had been investigated. CTL were induced polyclonally in vitro by stimulation of normal C57BL/6 spleen cells with concanavalin A (Con A)and their cytolytic activity was tested against 51Cr-labeled target cells in the presence of Bacto Phytohemagglutinin M. With this system, CTL activity could first be detected 48 h after exposure of spleen cells to Con A. Addition of cytosine arabinoside at concentrations sufficient to reduce DNA synthesis by 95-98% in Con A-stimulated cultures did not significantly inhibit the generation of cytolytic activity on a cell-to-cell basis. These results demonstrate that derepression of the genetic information required for the expression of CTL function can occur in the absence of detectable DNA synthesis.

scholarly journals THE EFFECTS OF ANTIGENS AND OF PHYTOHEMAGGLUTININ ON RABBIT SPLEEN CELL SUSPENSIONS

1966 ◽  
Vol 124 (4) ◽  
pp. 621-634 ◽  
Author(s):  
G. Harris ◽  
R. J. Littleton
Keyword(s):  
Dna Synthesis ◽  
Spleen Cell ◽  
Cell Suspensions ◽  
Red Cells ◽  
Specific Response ◽  
Spleen Cells ◽  
Sheep Red Cells ◽  
Stimulation Of

Phytohemagglutinin (PHA) stimulated the rate of DNA synthesis in rabbit spleen cell suspensions. Unlike antigens, previous immunization to PHA was not necessary and the specific response could not be transferred by macrophages, although lymphocytes primed by incubation in PHA were able to stimulate other spleen cells not directly exposed to PHA. When rabbits were stimulated by in vivo immunization with antigens, spleen cells proliferating in response to antigen were stimulated to divide by in vitro contact with PHA. Using the technique of specific hemolytic plaque formation by individual cells synthesizing γM-antibody to sheep red cells (plaque-forming cells), no evidence was obtained that stimulation of cell division by PHA resulted in specific antibody formation, although the presence of antigen resulted both in stimulation of cell proliferation and the production of plaque-forming cells. The presence of both sheep red cells and PHA in the medium of the same cell suspensions did not enhance the production of plaque-forming cells although there was a summative effect on DNA synthesis.

Thrombopoietin-Induced Stimulation of Megakaryocyte- Enriched Bone Marrow Cultures

1979 ◽  
Author(s):  
K. L. Kellar ◽  
B. L. Evatt ◽  
C. R. McGrath ◽  
R. B. Ramsey
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Bone Marrow Cells ◽  
Rabbit Plasma ◽  
Bone Marrow Cultures ◽  
Plasma Fractions ◽  
Marrow Cultures ◽  
Stimulation Of

Liquid cultures of bone marrow cells enriched for megakaryocytes were assayed for incorporation of 3H-thymidine (3H-TdR) into acid-precipitable cell digests to determine the effect of thrombopoietin on DNA synthesis. As previously described, thrombopoietin was prepared by ammonium sulfate fractionation of pooled plasma obtained from thrombocytopenic rabbits. A control fraction was prepared from normal rabbit plasma. The thrombopoietic activity of these fractions was determined in vivo with normal rabbits as assay animals and the rate of incorporation of 75Se-selenomethionine into newly formed platelets as an index of thrombopoietic activity of the infused material. Guinea pig megakaryocytes were purified using bovine serum albumin gradients. Bone marrow cultures containing 1.5-3.0x104 cells and 31%-71% megakaryocytes were incubated 18 h in modified Dulbecco’s MEM containing 10% of the concentrated plasma fractions from either thrombocytopenic or normal rabbits. In other control cultures, 0.9% NaCl was substituted for the plasma fractions. 3H-TdR incorporation was measured after cells were incubated for 3 h with 1 μCi/ml. The protein fraction containing thrombopoietin-stimulating activity caused a 25%-31% increase in 3H-TdR incorporation over that in cultures which were incubated with the similar fraction from normal plasma and a 29% increase over the activity in control cultures to which 0.9% NaCl had been added. These data suggest that thrombopoietin stimulates DNA synthesis in megakaryocytes and that this tecnique may be useful in assaying thrombopoietin in vitro.

scholarly journals Immunologic stimulation of early murine hematopoiesis and its abrogation by cyclosporin A

Blood ◽  
1982 ◽  
Vol 59 (4) ◽  
pp. 851-856 ◽  
Author(s):  
SA Burstein ◽  
SK Erb ◽  
JW Adamson ◽  
LA Harker
Keyword(s):  
Immune Response ◽  
Cyclosporin A ◽  
Progenitor Cells ◽  
Pokeweed Mitogen ◽  
Normal Rabbit Serum ◽  
Lymphocyte Function ◽  
Spleen Cells ◽  
Stimulation Of

Abstract Mice injected chronically with antiplatelet serum develop an increase in the number of megakaryocytic progenitor cells compared to animals given normal rabbit serum. To examine the specificity of this response, progenitor cells giving rise to megakaryocyte, granulocyte-macrophage, erythroid, and mixed-cell colonies were assayed after injection of various heterosera or saline. All four colony types increased in the serum-treated groups. Since the in vitro proliferation of hematopoietic progenitor cells is promoted by supernatants of mitogen-stimulated spleen cells, we hypothesized that the immune response following antiserum administration resulted in the in vivo activation of T lymphocytes which produced or led to the production of colony stimulating activities. To test this hypothesis, cyclosporin A, a preferential inhibitor of T lymphocyte function, was given to mice concurrently with antiserum and also added to spleen cell cultures in the presence of pokeweed mitogen. Cyclosporin A abrogated the antiserum- related increases in progenitor cell numbers in vivo and the production of colony stimulating activity in vitro. The results suggest that the immune response related to antiserum administration results in the in vivo production of hematopoietic colony stimulating activities that may be identical to those produced in vitro by mitogen-stimulation of spleen cells.

Stimulation of cell division and DNA replication inPrototheca richardsiby passage through larval amphibian guts

Parasitology ◽  
1993 ◽  
Vol 107 (2) ◽  
pp. 119-124 ◽  
Author(s):  
T. J. C. Beebee ◽  
A. L.-C. Wong
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Growth Inhibition ◽  
Dna Synthesis ◽  
Free Living ◽  
Leucine Uptake ◽  
Amphibian Larvae ◽  
Larval Amphibian ◽  
Stimulation Of

SUMMARYPrototheca richardsi, an unpigmented heterotrophic alga, causes growth inhibition in amphibian larvae and has proved refractory to culturein Vitro.P. richardsireplication is dependent on regular passaging through tadpole digestive systems; uptake of thymidine by free-livingProtothecacells and incorporation into DNA are very low by comparison with leucine uptake and incorporation into protein, but DNA synthesis is detectable in cells isolated from tadpole intestines. DNA replication was elicited 6–8 h after ingestion in protothecans fed to tadpoles and subsequently re-isolated from them, providing that the tadpoles were fed subsequent to the ingestion. It appears that passaging through tadpole intestines provides an essential stimulus to maintaining an active cell division cycle inP. richardsi.

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