Immunoenhancing activity of NPT 15392: a potential immune response modifier

NPT 15392, a new immunomodulating compound related to inosine in structure and isoprinosine in action, enhances T-cell dependent immune responses. Antibody responses to sheep red blood cells are augmented two to threefold in mice receiving NPT 15392 while T-cell independent antibody responses to TNP-LPS are unaffected. NPT 15392 does not enhance or alter the number of clonable B cells. This drug also increases cytotoxic T-lymphocyte responses to allogeneic tumor cells but does not alter the number of cytotoxic precursor cells. Immature hematopoietic cell classes (clonable progenitor cells) were also monitored and found not to be influenced by NPT 15392.

Differences in the regulation of megakaryocytopoiesis in the murine bone marrow and spleen

Murine splenic megakaryocytopoiesis has been analysed and compared to that of the bone marrow. Quantification of megakaryocytes by acetylcholinesterase staining indicated a reduction in the total numbers of megakaryocytes in the spleen, with the largest decrease being in the total numbers of immature megakaryocytes. On a per organ basis, the spleen also contained a lower number of the megakaryocyte progenitor cells (CFU-Mk) than the bone marrow. The splenic and bone marrow progenitor cells had similar in vitro responses to megakaryocyte colony-stimulating activities. However, the splenic progenitor cells developed a lower number of megakaryocytes per colony, compared to bone marrow. This lower number of cell divisions was not compensated by increased endomitotic activity, since the splenic colony megakaryocytes had a similar distribution of DNA to those derived from marrow megakaryocytes. Cell cycle analysis indicated that, in contrast to marrow cells, splenic megakaryocyte progenitor cells are a rapidly-cycling population. This change in cell cycle status, together with altered proportions of progenitor cells, immature and mature megakaryocytes, suggests that the regulation and kinetics of megakaryocyte development are different in spleen and bone marrow.

Immature Megakaryocytes in the Mouse: Morphology and quantitation by acetylcholinesterase staining

Three types of immature megakaryocytes, detected by their morphological properties, have been characterized in bone marrow of normal C57BL/6 mice. Morphological classification of these cells was carried out by determining (1) presence and relative amount of acetylcholinesterase, (2) cell size, (3) nuclear/cytoplasm ratio, and (4) nuclear shape. The immature megakaryocytes were classified as: (A) cells distinguished by a round nucleus (10.6 +/- 1.1 mu diameter; mean +/- SEM), which had the highest nucleus / cytoplasm ratio and lowest content of acetylcholinesterase; (B) cells with an indented nucleus (13.0 +/- 1.9 mu diameter), which had increased acetylcholinesterase content and reduced nucleus/cytoplasm ratio compared to the round-nucleus cell type; and (C) lobed-nucleus cells (14.5 +/- 2.9 mu diameter), which showed further increase in acetylcholinesterase content and reduction in nucleus/cytoplasm ratio. Increased numbers of immature megakaryocytes were detected, indicating that a proportion of these cells are undetected using conventional staining techniques. Based on the observed alterations in size, acetylcholinesterase content, and nuclear complexity, it was concluded that these cells constitute part of a progressive maturation sequence intermediate between the progenitor cell (CFU-Mk) and mature easily recognizable megakaryocytes.

Cell interactions influencing murine marrow megakaryocytes: nature of the potentiator cell in bone marrow

Auxiliary bone marrow cells are required for optimal murine megakaryocyte colony formation in addition to progenitor cells and a colony stimulating activity (CSA) present in WEHI-3 cell conditioned medium. These auxiliary cells are adherent, with a sedimentation rate of 5.8 mm hr-1 and buoyant density of 1.065-1.078 gcm-3. The activity from bone marrow cells is loss at irradiation doses above 900 rad. Bone marrow cells with these characteristics, and supernatants from lung, bone shafts, and peritoneal exudate cells were all active in enhancing megakaryocyte colony incidences in mouse bone marrow cultures above those stimulated by an obligatory activity in WEHI-3 cell conditioned medium. Certain macrophage cell lines (J774, P388D1) could elaborate the activity. This study confirms that a potentiation activity enhances CSA stimulation of megakaryocyte colony formation. The potentiator is elaborated by bone marrow cells in limiting amounts requiring either high cell concentrations or an exogenous source of the activity for optimal colony growth.

Abrogation of the non-specific toxicity of abrin conjugated to anti-lymphocyte globulin

A covalent conjugate of abrin and anti-human lymphocyte globulin (AHLG) was prepared in an endeavour to create a cytotoxic agent with specificity for human lymphoid cells. The AHLG--abrin conjugate was found to be around 10-fold better able to inhibit 3H-leucine uptake by the human lymphoblastoid cell line, Daudi, in tissue culture than was the control conjugate comprising abrin and normal IgG (nIgG). Both materials were less potent than native abrin. Galactose, which is known competitively to antagonize the binding of abrin to cells, strongly inhibited the toxicities of abrin and the nIgG--abrin conjugate whereas that of ALG--abrin was unimpaired. Thus, at least for Daudi cells in tissue culture, abrin can be made selectively toxic, by linkage to AHLG, towards cells bearing antigens to which the antibody moiety of the conjugate can attach.

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Limitation of macrophage production in long-term marrow cultures containing prostaglandin E

Addition of prostaglandin E2 (PGE2) significantly altered the cellular composition of murine long-term bone marrow cultures. After 4--5 weeks of culture, increased cellularity in the suspension phase was observed in all cultures containing prostaglandin. These suspension cells contained markedly higher proportions of differentiated neutrophils than did cells cultured in the absence of PGE2. Granulocyte-macrophage progenitor cell levels in the suspension layer were increased 3--20 fold after five weeks in prostaglandin-containing cultures compared with control cultures. Fewer cells comprised the adherent layer in cultures containing prostaglandin. The number of macrophages in this layer was reduced 3--8 fold in these cultures compared with control cultures, while the number of granulocytes was increased 2--3 fold. The progenitor cells biased toward macrophage development were selectively inhibited in the cultures with PGE2. There was no significant effect of PGE2 on pluripotent stem cell levels or on the longevity of the cultures. It is concluded that excessive monopoiesis in bone marrow may be limited by PGE2 without influencing either stem cell maintenance or the development of other marrow-derived cell types.

The effect of mouse lung granulocyte-macrophage colony-stimulating factor and other colony-stimulating activities on the proliferation and differentiation of murine bone marrow cells in long-term cultures

The roles of colony-stimulating factors in long-term bone marrow cultures were studied and compared. After single additions of high concentrations of unpurified colony-stimulating activities to the cultures, rapid deterioration of the cultures was observed. This appears to result from contaminants in the stimulatory preparations. Cultures to which one purified colony-stimulating factor (csf) from endotoxin mouse lung-conditioned medium was added did not run down ten weeks after addition and were found to be the same as the controls. The deterioration of the cultures to which unpurified stimulators were added could not be accounted for by accelerated granulopoiesis leading to subsequent exhaustion of the cultures. The inability of purified CSF to affect the cellularity of the suspension cells did not result from instability or masking of the activity in the cultures, nor did CSF preferentially stimulate the cells within the adherent layer. The suspension cells responded to purified CSF after separation from the adherent cells. The data suggest that if CSFs are marrow stimulators, their effects in turn may be stringently regulated within the marrow.

The maturation state of three types of granulocyte/macrophage progenitor cells from mouse bone marrow

The progenitor cells of neutrophil granulocytes and macrophages which are able to proliferate and differentiate in vitro (CFU-c) form a heterogeneous population. By the use of specific colony stimulating activities and cell separation by equilibrium density centrifugation, three subpopulations of CFU-c can be detected. These three CFU-c are characterized by buoyant densities of 1.070, 1.075 and 1.080 g.cm-3 and by their proliferative response to 18 h postendotoxin serum, colony stimulating factor from extracts of mouse embryos and uteri (CSF-pmue) and erythrocyte lysate, respectively. The three CFU-c are compared with respect to their differentiation potential, the maturation rate of their progeny cells and their proliferation capacity. It is shown that with increasing density of the CFU-c the maturation rate increases (sequential maturation of colonies derived from CFU-c with densities of 1.080, 1.075, 1.070 g.cm-3) and the proliferation capacity decreases (colony size decreases in the sequence of CFU-c with densities 1.070, 1.075, 1.080 g.cm-3). Concerning the differentiation potential it is shown that all three CFU-c detected have the capacity to form granulocytes as well as macrophages. On the basis of these results it is concluded that the CFU-c with densities of 1.070, 1.075 and 1.080 g.cm-3 represent a maturation sequence.

Matching of chemotherapy to mouse strain and lymphoid tumor type to prevent tumor-induced suppression of specific T- and B-cell functions

Specific immunological and hematopoietic functions were studied during treatment with antineoplastic agents in mice bearing syngeneic lymphoid tumors: 70Z/2, a B-cell lymphoma of C57BL X DBA/2 F1 (hereafter called (BD2F1) mice; EL4, a T-cell lymphoma of C57BL/6 mice; or J774, a macrophage tumor of BALB/c mice. Both B- and T-lymphocyte function (antibody-forming cells and cell-mediated lymphocyte lympholysis toward alloantigens) were suppressed in spleen cells of mice bearing these tumors. Other hematopoietic functions (granulocyte, macrophage, and megakaryocyte progenitor cells) were variably influenced by growth of these lymphoid tumors. J774 enhanced, but 70Z/2 suppressed, megakaryocyte progenitor cells. J774 and 70Z/2 increased levels of granulocyte-macrophage progenitor cells. EL4, the T-cell lymphoma, did not influence either cell type. Significant variation in strain sensitivity to drug toxicity and drug effectiveness in different tumor-host systems was observed. Increased median survival time with reversal of tumor-induced immune dysfunction, without toxicity to hematopoietic progenitor cells, was realized in two tumor-host-drug combinations. Polyinosinic-polycytidylic acid was effective against J774, while actinomycin D was active against 70Z/2. Mitomycin C effectively reduced tumor load, as evidenced by loss of splenic tumor colony-forming cells for all three tumors. This agent prolonged survival and concomitantly restored immunological responsiveness in hosts immunosuppressed by growth of 70Z/2 or J774. Paralleling tumor reduction with mitomycin C therapy, the splenic hematopoietic progenitor and colony-forming B-cells were reduced in tumor-bearing and tumor-free mice, thus compromising its therapeutic effectiveness. 1-beta-D-Arabinofuranosylcytosine reduced tumor load with marginal toxicity toward hematopoietic progenitor and colony-forming B-cells. However, immune responsiveness was only partially restored, and median survival was not increased. The results presented show the diversity of therapeutic drug effectiveness in increasing mean survival time and influencing other life-sustaining parameters (immunological and hematopoietic functions).

Isolation of pluripotent hemopoietic stem cells and clonable precursor cells of erythrocytes, granulocytes, macrophages and megakaryocytes from mouse bone marrow

Murine pluripotent hematopoietic stem cells and precursor cells with restricted commitment to erythrocytes, granulocytes and macrophages as well as megakaryocytes have been purified 30- to 50-fold from mouse bone marrow cells. Purification was achieved by a three-step procedure. Bone marrow cell populations free of erythroid cells and lymphocytes were obtained by culturing the cells for several weeks. Macrophages and adherent polymorphic neutrophils (PMN) were removed by adherence to plastic. The remainder of the PMN along with more primitive granulocytes (but not promyelocytes and some monocytoid cells) were removed either by neutral density centrifugation or by differential centrifugation after rosette formation with sheep erythrocytes coated with immunoglobulin (EA rosettes). The remaining population of marrow-derived cells contained 40-66% blast cells, 20-35% promyelocytes and 5-10% other cells (usually PMNs and monocytes). Using cloning techniques to detect immature hemopoietic cells, this population contained 15-35% granulocyte-macrophage progenitor cells, approximately 0.2% erythroid burst-forming cells, approximately 0.1% megakaryocyte progenitor cells and 1-3% pluripotent stem cells (based on seeding efficiency 0.06).

Immune adherence of platelets to sensitized leukocytes: a model of hyperacute rejection

Specifically hypersensitized recipients of canine renal allotransplants demonstrate an accumulation of host platelets in the transplanted kidney within minutes following implantation. Transplant function is ra,idly lost. The present work describes an in vitro model of this hyperacute rejection mechanism. Renal donor leukocytes sensitized with host serum are incubated with donor platelets. Within a few minutes the platelets adhere to the sensitized leukocytes to form rosettes. Serum complement is required for platelet rosette formation. Platelets act as indicators in this reaction and they may be obtained from any dog. Donor platelets were used to avoid the transfer of specific antibody to the test mixture. The in vitro model supports the view that hyperacute rejection in the dog is a specific example of the immune adherence reaction in which platelets bind to antigen-antibody-complement complexes.

Abnormalities in clonable B lymphocytes and myeloid progenitors in autoimmune NZB mice

Cloning procedures were used to study B lymphocytes and progenitors of granulocytes and macrophages in NZB mice. Numbers of B cells that were detected in sheep erythrocyte-containing semisolid cultures were only slightly elevated in NZB tissues, and these were normally sensitive to inhibition by anti-mu or anti-delta antibodies or prostaglandin E. However, NZB mice rapidly developed large numbers of B cells that could be cloned in the presence of lipopolysaccharide, and these included unusual anti-mu resistant cells. Numbers of myeloid precursors in NZB bone marrow that were responsive to colony-stimulating activity in L-cell conditioned medium or endotoxin serum were at least normal, but at all ages granulocyte-macrophage precursors were poor responders in cultures stimulated by WEHI-3 cell conditioned medium. Almost no colonies were elicited in NZB cultures with a colony-stimulating activity moiety from WEHI-3 cells. Prostaglandin sensitivity of myeloid precursors from NZB and CBA mice was also different. Codominant genetic control of these abnormalities was suggested by their partial expression in F1 hybrid NZB X CBA and NZB X NZW mice. NZB mice expressed an unexpected IgD allotype allele.

Human megakaryocytes. I. Characterization of the membrane and cytoplasmic components of isolated marrow megakaryocytes

Human marrow megakaryocytes have been isolated with high purity and yield by processing marrow cells sequentially through density centrifugation and velocity sedimentation. Analysis of the isolated cells for various platelet-associated components by immunofluorescence demonstrated that fibrinogen, plasma factor VIII antigen (factor VIII:AGN) platelet myosin, platelet glycoproteins I and III are present on the membrane and in the cytoplasm of over 90% of marrow megakaryocytes. Parallel studies of human and mouse megakaryocytes and platelets for IgG receptor (FcR), complement receptor type one (CR1) (C3b receptor), complement receptor type two (CR2) (C3d receptor), and Ia antigen by fluorescence and (or) rosette formation methods were performed. FcR were present on most human megakaryocytes and platelets. The Ia antigen was detected on a proportion (10-15%) of human megakaryocytes but it was undetectable on human platelets. CR1 was found on 20-40% of mouse megakaryocytes and also on a proportion of mouse platelets. These differentiation markers may be of use in monitoring megakaryocyte maturation.

Preferential inhibition of murine macrophage colony formation by prostaglandin E

Murine bone marrow progenitor cells that gave rise to macrophage colonies in semisolid agar were found to be more sensitive to prostaglandins of the E series (PGE) than were precursor cells of granulocytes and megakaryocytes. Macrophage colonies themselves had different sensitivities to the molecule. Precursor cells of macrophages that formed colonies in the presence of a stimulating activity from L cells (L-cell CSA) were inhibited to 50% levels by 3 x 10(-9)-M PGE. Macrophage progenitor cells, which require both L-cell CSA and rat hemolysate for colony growth, were inhibited to the same level by 3 x 10(-7)-M PGE. Other colony types (granulocytes and megakaryocytes) were sensitive to PGE only at concentrations greater than 10(-6) M. Accordingly, addition of different PGE concentrations to the culture assay should allow easy detection of precursor cells with morphologically distinct end cells. The different sensitivities to PGE of two macrophage colony types of different maturation stages indicate that PGE may provide feedback to control macrophage formation by inhibiting proliferation and differentiation of immature monocytoid cells.

Maturation and regulation of megakaryocytopoiesis

The in vitro cloning technique for detecting megakaryocyte precursor cells was employed to compare stimuli known to influence megakaryocytopoiesis. Preparations of thrombopoietic stimulating factor (TSF) did not directly stimulate the growth of megakaryocyte colonies (CFU-m) but increased the frequency of CFU-m when TSF was added to the cultures with a constant amount of megakaryocyte colony stimulating factor. Platelets or platelet homogenates did not influence the frequency of CFU-m or the size of individual colonies. Analysis of cell surface properties of megakaryocytes obtained either by isolation from bone marrow or from in vitro colonies revealed species differences. The possibility that megakaryocytopoiesis and platelet release are regulated both within the marrow as well as by humoral factors is discussed.

The effect of morphine on the endogenous phosphorylation of synaptic plasma membrane proteins of rat striatum

The synaptic plasma membrane (SPM) fraction was prepared from rat striata and assayed for endogenous phosphorylation in vitro. After the separation of membrane proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the incorporation of phosphate into specific membrane proteins was analyzed by gel slicing and autoradiographic techniques. Phosphate was incorporated into several SPM protein bands, two of which were regulated by cyclic adenosine 3':5' monophosphate. As a consequence of the chronic (in vivo) administration of morphine, the phosphorylation of two protein bands, designated protein II (MW 48,000-52,000) and protein III (MW 11,000-18,000), was reduced by approximately 20 and 50%, respectively; the phosphorylation of the former proteins was regulated by cyclic adenosine monophosphate whereas the phosphorylation of the latter proteins was not. The incorporation of phosphate into these same two protein bands was similar to control values when the membranes were obtained from rats undergoing naloxone-precipitated withdrawal. Morphine, in vitro, did not alter the phosphorylation of any SPM proteins in the assay, although at a high concentration morphine did antagonize the calcium-stimulated phosphorylation of one or more proteins in band II. The development of tolerance to and dependence on opiates may include changes in the phosphorylation of specific SPM proteins.

Effect of myleran on murine hemopoiesis. III. Changes in the density distribution of spleen colony forming (CFU-S) and agar gel colony forming cells (CFU-C)

Spleen colony forming cells (CFU-S) and agar-gel colony forming cells (CFU-C) are separate but heterogeneous cell populations, as measured by buoyant density. Myleran (MY) abrogated the major (lighter density) components of the CFU-S and CFU-C compartments, thus shifting the surviving CFU-S and CFU-C density profiles into the higher density region. The normal spleen colony erythrocytic : granulocytic (E:G) ratio profile showed three density regions with different distributions of erythroid and granulocytic colonies. The preponderantly erythrocytic colony-generating CFU-S of the intermediate density regions were eradicated by MY. Comparison of the density distribution of erythrocytic and granulocytic colony-generating CFU-S of normal bone marrow showed that the erythrocytic CFU-S profile paralleled that of total CFU-S, while most of the granulocytic CFU-S were contained in the major (and lowest density) peak. MY eradicated the two main (and lowest density) peaks of CFU-S; surviving CFU-S occurred preponderantly in a minor (higher density) peak which has a high potential for generating erythrocytic colonies.

Effect of smoking during pregnancy upon the haematological values of cord blood

Haematological indices in cord blood, measured by a Coulter Counter, in 50 mothers who smoked 10 or more cigarettes a day were compared with those in 75 control mothers who were non-smokers, but of similar age and parity. Smoking during pregnancy was associated with higher levels, of haemoglobin, and the haematocrit, as well as with higher red cell counts and a higher mean corpuscular haemoglobin. The percentage of fetal haemoglobin in cord blood was not affected by smoking. There was no correlation between social class and cord blood haemoglobin; but within social class groups, higher cord blood haemoglobin levels were associated with smoking. It is suggested that smoking during pregnancy stimulates fetal erythropoeisis.