Biomedical subjects

J M Manske

Publications and source records attributed to J M Manske.

5 recordsLinked to original sources

PubMed1995

Substance P mediated stimulation of cytokine levels in cultured murine bone marrow stromal cells.

Substance P (SP) is a neuropeptide which has been reported to have immunomodulatory activity. Most studies on SP have been performed on cells of the peripheral immune system. More recently, SP has been reported to have stimulatory activity on human bone marrow cells in vitro, and this activity was dependent on the presence of an adherent layer of cells. The in vitro adherent layer represents the stromal cells of the marrow. In this study, we directly addressed the effect of SP on cultured bone marrow stromal cells. Since stromal cells play an important role in the regulation of hematopoiesis, interactions of neuropeptides such as SP with this cell population could lead to an alteration of stem cell development within the bone marrow. Previously we have shown that SP stimulates protein synthesis in this cell population with two waves of protein synthesis activation, after 2 hr and 48 hr of SP incubation. In this study, we asked whether levels of known stromal cell cytokines were altered in response to SP incubation. We assayed the levels of Interleukin-7 (IL-7) and Stem Cell Factor (SCF) associated with the stromal cell surface following 2 hr and 48 hr of SP incubation. Cells were stimulated with SP for 2 hr or 48 hr. Following SP incubation, cells were washed and the levels of cell associated cytokine was determined by ELISA. Following 2 hr of treatment, 0.1 nM of SP significantly increased (p = 0.05) the level of IL-7 as compared to untreated controls. After 48 hr of treatment, 1, 10, and 100 nM SP significantly increased the levels of IL-7 in this cell population. When SCF levels were assayed, SP at all concentrations tested was found to increase significantly the levels of SCF following 2 hr of incubation. Following 48 hr of incubation, 10 and 100 nM of SP significantly increased the levels of SCF. The ability of SP to affect cytokine levels varied with time. Following 2 hr of SP incubation, cytokine levels were enhanced at the lower end of the concentration range as compared to 48 hr of SP treatment. A 48 hr incubation with SP yielded the highest levels of cytokine at the higher end of the concentration range. Taken together, the results of these studies suggest that SP has an immunoregulatory effect on bone marrow stromal cells leading to alteration in the production and/or secretion of regulatory cytokines such as IL-7 and SCF.

Adjuvants, Immunologic↗

PubMed1989

The role of ricin B chain in the intracellular trafficking of anti-CD5 immunotoxins.

The mAb anti-CD5 was linked to purified ricin A chain (RTA) or intact ricin (Rc) containing B chain to determine the role of ricin B chain in the intracellular trafficking of anti-CD5 immunotoxins (IT). IT were radiolabeled with iodine-125 and then studied for their subcellular compartmentalization in an acute lymphoblastic leukemia T cell line, CEM. Ricin A chain IT was not as toxic to CEM cells as Rc-IT in protein synthesis inhibition assays. This difference was not attributed to differential binding or modulation of the CD5 determinant from the cell surface as measured by FACS analysis. However, we found a relationship between the toxicity of anti-CD5-Rc and anti-CD5-RTA and their ability to traffic to CEM lysosomes. Kinetic analysis of the transfer of radioimmunotoxin to the lysosomes showed that anti-CD5-Rc was trafficked significantly more slowly than anti-CD5-RTA, perhaps due to an extended period of time in the Golgi compartment. The possibility of a Golgi interaction was tested by adding monensin, a carboxylic ionophore that interrupts trafficking through the Golgi, to cells treated with anti-CD5-RTA. The addition of monensin caused anti-CD5-RTA to traffic in a manner identical to anti-CD5-Rc. We conclude that 1) B chain slows trafficking of anti-CD5-Rc to the lysosomes; 2) the rate-limiting step in the toxicity difference between anti-CD5-Rc and anti-CD5-RTA is the rate of transfer to the lysosomes; and 3) trafficking through the Golgi may be important for anti-CD5-IT toxicity.

Animals↗

PubMed1988

Cytotoxic effects of anti-CD5 radioimmunotoxins on human tumors in vitro and in a nude mouse model.

An immunoconjugate, consisting of both toxin and radionuclide on the same antibody molecule, was synthesized by cross-linking the phytotoxin ricin to the T101 monoclonal antibody recognizing the CD5 cluster expressed on normal and malignant T-cells. The hybrid molecule was then labeled with iodine-125 by an iodine monochloride procedure. This radioimmunotoxin (RIT), which selectively bound to the CD5-positive CEM human leukemia cell line, was selectively inhibitory to antigen-positive cells in protein synthesis inhibition assays. RIT was only 3.0-7.8-fold less toxic and was 1.1-1.6-fold slower than unlabeled immunotoxin in inhibiting protein synthesis. Because of the radionuclide moiety, the RIT also provided information related to biodistribution and pharmacokinetics. Four days following intratumoral injection, more than 125-fold greater activity was found in CEM tumors implanted in nude mice as compared to normal tissues. The mean blood half-life for RIT was 25.7 h and for radiolabeled antibody, 91.3 h. Intratumoral injections of RIT selectively induced regression of established CEM tumors. To our knowledge, these studies are the first to demonstrate that a single immunoconjugate can combine the advantages of both a catalytic toxin and radionuclide for cancer therapy.

Animals↗

PubMed1987

Combined immunochemotherapy of human solid tumors in nude mice.

In vivo immunochemotherapy of human solid tumors was studied in a nude mouse model. Large tumors (3 to 6 cm3) were induced by s.c. injection of the acute lymphoblastic leukemia T-cell line CEM. Transient tumor inhibition could be achieved by intratumoral injection of an intact-ricin immunotoxin that specifically recognizes a determinant CD5 (T,p67) expressed on the cell surface. Injection of the in vitro active cyclophosphamide congener mafosfamid had little effect on the progression of tumor growth. A combination regimen of immunotoxin and mafosfamid induced the most dramatic antitumor effect; a 72 to 100% reduction in tumor volume was observed within 3 to 4 days posttreatment. However, tumors relapsed within 5 to 13 days. Persistent, tumor regression was observed only when protocols using successive injections of combined immunotoxin/mafosfamid were used. All seven mice undergoing this treatment had a precipitous decrease in tumor size, and 86% survived greater than 30 days posttreatment. No residual tumor was detectable on Day 30 in five of seven mice. Regression was partly attributed to the selective activity of immunotoxin, since successive injections of an irrelevant control immunotoxin coupled to ricin in combination with mafosfamid did not reduce tumor size. Thus, we have demonstrated that a combination of anticancer chemotherapy and immunotoxin therapy yielded a greater antitumor effect than either therapy alone.

Animals↗

PubMed1986

Antigenic modulation by anti-CD5 immunotoxins.

We evaluated the modulation of T101 immunotoxins (IT) and free T101 antibody from the surface of normal and leukemic cells to determine whether the presence of toxin on antibody affected antigenic modulation. Reagents were made by conjugating T101, which binds to the T cell antigen CD5, to either intact ricin or purified ricin A chain. We found that T101-A chain modulated CD5 more efficiently than T101-ricin, which modulated CD5 more efficiently than T101 alone. Kinetic studies showed that maximal modulation of IT was reached within 3 hr. When toxicity of the reagents was tested in protein synthesis inhibition assays, T101-ricin in the presence of lactose inhibited 99% of the protein synthesis of CEM cells. T101-A chain was less toxic, inhibiting protein synthesis only 23 to 43%. The addition of the potentiating agent monensin nearly doubled the toxicity of T101-A chain, but did not affect T101-A chain modulation. To determine the fate of bound IT, T101 and T101-ricin were labeled with 125I. Cells were incubated under modulating conditions in the presence of radiolabeled reagents. T101 and T101-ricin were internalized into CEM cells. In contrast, T101, but not T101-ricin, appeared to be shed from peripheral blood mononuclear cells. Our findings show clearly that: 1) the presence of toxin on antibody does not inhibit--and may actually enhance--modulation; 2) T101-IT are internalized, not shed from the cell surface; 3) the lack of toxicity of T101-A chain is not attributed to inability to modulate; 4) there is no correlation between enhancement of T101-A chain toxicity by monensin and antigenic modulation by A chain reagents; and 5) modulation, which is undesirable in monoclonal antibody therapy, may be advantageous in the therapeutic use of IT.

Adjuvants, Immunologic↗