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Biomedical subjects

D E Kern

Publications and source records attributed to D E Kern.

At least 37 records · Page 2Linked to original sources
PubMed1988

IL-4-induced lymphokine-activated killer cells. Lytic activity is mediated by phenotypically distinct natural killer-like and T cell-like large granular lymphocytes.

The purpose of the current study was to characterize lymphokine-activated killer (LAK) activity induced with IL-4/B cell stimulatory factor-1 and to compare IL-4-induced LAK activity with IL-2-induced LAK activity. Culture of murine lymphocytes with high concentrations of IL-4 induced nonspecific lytic activity against a wide variety of tumors. Lytic activity induced by IL-4 increased with increasing concentrations of IL-4 over the range of 1.0 to 25 ng/ml. The kinetics of LAK induction by IL-4 and IL-2 were similar; however, IL-4 was less effective than IL-2 in maintaining lytic activity for longer culture periods and provided lower viable cell yields than did IL-2. Similar to IL-2, IL-4 induced blastogenesis and the generation of large granular lymphocytes, all LAK activity observed was exclusively associated with the large granular lymphocyte fraction, and the cytolytic effector cells were heterogeneous in regards to cell surface phenotype. The majority of IL-4-induced lytic activity was associated with mutually exclusive NK-like (i.e., NK-1.1+ Lyt-2-) and T cell-like (i.e., NK-1.1- Lyt-2+) LAK cells. The precursors for each subset were distinct and expressed the asialo-GM1+ Lyt-2- and the asialo-GM1+ Lyt-2+ phenotypes, respectively. Although IL-4-induced LAK effector cells were morphologically and phenotypically similar to IL-2-induced LAK cells, IL-2 generated equivalent numbers of T cell-like and NK-like LAK cells, whereas IL-4 generated 3.5-fold more T cell-like LAK cells than NK-like LAK cells. It might eventually be possible to exploit the preferential activation of T cell-like LAK by IL-4 for therapeutic advantage.

Animals↗
PubMed1987

Lyt-2+ cells. Requirements for concanavalin A-induced proliferation and interleukin 2 production.

The requirements for inducing Lyt-2+ T cell proliferation in response to concanavalin A (Con A) were examined. Purified Lyt-2+ or L3T4+ spleen cells of C57BL/6 origin were stimulated with Con A and syngeneic macrophages (MO) in the presence of monoclonal antibodies to T cell markers or to polymorphic determinants on major histocompatibility complex molecules, and assessed for the ability to proliferate and to produce interleukin (IL) 2. alpha I-Ab failed to inhibit the Con A response of Lyt-2+ cells at dilutions that significantly inhibited the response of L3T4+ cells. In contrast, alphaKb/Db or alpha Lyt-2.2 specifically inhibited the response of Lyt-2+ cells, but not L3T4+ cells. The ability of alpha Kb/Db and of alpha Lyt-2.2 to inhibit the response of Lyt-2+ cells was dependent upon the concentration of Con A. These data demonstrate that optimal triggering of T cell subsets to proliferate and to produce IL-2 in response to Con A requires interactions with the appropriate restricting major histocompatibility complex molecule. The role of accessory cells in Lyt-2+ Con A-induced proliferation and IL-2 production was also investigated. Purified Lyt-2+ cells and purified L3T4+ cells failed to respond to Con A in the absence of MO. IL-1 reconstituted the response when MO were limiting, but failed to restore the response of either Lyt-2+ or L3T4+ cells when T cells were rigorously purified to remove all MO. These results demonstrate that triggering Lyt-2+ T cells, like L3T4+ T cells, requires accessory cells, and that this does not merely reflect a requirement for IL-1 production. Thus, Con A-induced proliferation and IL-2 production by Lyt-2+ T cells requires intimate contact with accessory cells and interactions dependent upon the class I-restricting element.

Animals↗
PubMed1987

Antigen-driven T cell clones can proliferate in vivo, eradicate disseminated leukemia, and provide specific immunologic memory.

The aim of the current study was to determine the ability of antigen-driven cloned helper cell independent cytotoxic T lymphocytes (HITc) to proliferate and to survive in vivo and to mediate tumor therapy. The HITc clone utilized (denoted 1.B6) was specifically cytolytic to FBL-3, a syngeneic Friend virus-induced murine leukemia. Activation in vitro (48 hr) with FBL-3 induced secretion of interleukin 2 (IL 2), expression of IL 2 receptors (IL 2R), and in vitro proliferation. These cells could be "rested" for several weeks without stimulation, which resulted in reduced expression of IL 2R; however, restimulation with antigen resulted in reinduction of IL 2R and proliferation. The ability of cloned HITc to proliferate and to survive in vivo was examined in cyclophosphamide (CY) pretreated donor mice congenic for the Thy-1 gene. Adoptively transferred cloned HITc could be found in large numbers, and were widely distributed in vivo 1 wk after transfer. In tumor therapy, 1.B6 cells when injected into a site of tumor (i.p.) and used as an adjunct to CY were effective against disseminated FBL-3. In this circumstance, cloned 1.B6 cells could be recovered from cured mice 125 days after transfer and were shown to specifically lyse tumor and proliferate in vitro in response to FBL-3. Thus as an adjunct to CY, tumor-specific cloned HITc are capable of eradicating disseminated leukemia, persisting long-term in vivo, and providing specific immunologic memory.

Animals↗
PubMed1986

Eradication of disseminated murine leukemia by treatment with high-dose interleukin 2.

Interleukin 2 (IL 2) in high concentration induces lymphocytes to become nonspecifically cytolytic to a wide variety of tumor targets. We evaluated the therapeutic potential of such lymphokine-activated killer (LAK) cells in vivo and high-dose II 2 in vivo against disseminated murine leukemia. To quantitate the potential anti-leukemia effect of LAK cells in vivo, B6 mice were injected i.p. with graded doses of FBL-3 leukemia cells followed by LAK cells. In this Winn-type assay, 1 X 10(7) LAK cells were able to prevent the outgrowth of 1 X 10(2) FBL-3 cells in only 50% of mice and did not prevent the outgrowth of 1 X 10(6) tumor cells. Thus LAK cells, highly cytolytic to FBL-3 in vitro, mediated only a limited anti-tumor effect when applied directly to leukemia cells in vivo. LAK cells used as an adjunct to chemotherapy induced a small but non-curative effect against FBL-3, however. In this circumstance, LAK cells were markedly less effective than were immune spleen cells from mice previously sensitized to FBL-3. To test the anti-leukemia effect of high-dose IL 2 in vivo, B6 mice were inoculated with 5 X 10(6) FBL-3 cells followed by repeated doses of IL 2 at dose levels shown to induce LAK in vivo. "LAK-inducing" IL 2 doses on days 5 to 9 after FBL-3 inoculation, when tumor was disseminated, cured 50% of the mice. Treatment on days 5 to 9 was far more effective than on days 0 to 4, implying that the evolution of a host-tumor interaction was essential for the therapeutic effect of IL 2. Mice cured of FBL-3 by high-dose IL 2 were found to be immune to FBL-3, suggesting that tumor eradication resulted from a collaboration between LAK activity and tumor-specific immunity.

Animals↗
PubMed1986

Requirement for recognition of class II molecules and processed tumor antigen for optimal generation of syngeneic tumor-specific class I-restricted CTL.

The roles of Class II-restricted L3T4+ T cells and of accessory cells (AC) during the in vitro generation of Class I-restricted Lyt-2+ cytotoxic T cells (CTL) specific for a Class II-negative syngeneic tumor cell line, FBL, was examined. Treatment of responder FBL-immune spleen cells with alpha L3T4 plus complement before culture, as well as the direct addition of alpha L3T4 to cultures, diminished the generation of FBL-specific CTL. The contribution of L3T4+ cells could be completely replaced by the addition of exogenous cytokines. The data demonstrate that the optimal generation of FBL-specific Lyt-2+ CTL requires the presence of L3T4+ cells, presumably to provide necessary lymphokines. FBL-specific CTL could not be generated from purified FBL-immune T cells in the absence of AC. Syngeneic Ia+ macrophages (M phi), added at the initiation of culture, restored the response of purified T cells. Pretreatment of M phi with ammonium chloride or chloroquine, or the addition of monoclonal alpha I-Ab antibody at the initiation of culture, inhibited the ability of M phi to reconstitute the CTL response. Finally, the addition of exogenous helper factors could replace M phi and reconstitute the FBL-specific response of AC-depleted immune T cells. These results suggest that during the generation of Lyt-2+ CTL to a syngeneic tumor expressing only Class I MHC antigens, Ia+ AC are required to biochemically process antigen released from the tumor cells and present this modified antigen to Class II-restricted T helper cells.

Animals↗
PubMed1985

Therapy of disseminated murine leukemia with cyclophosphamide and immune Lyt-1+,2- T cells. Tumor eradication does not require participation of cytotoxic T cells.

The ability of noncytolytic Lyt-1+,2- T cells immune to FBL-3 leukemia to effect eradication of disseminated FBL-3 was studied. Adult thymectomized, irradiated, and T-depleted bone marrow-reconstituted (ATXBM) B6 hosts were cured of disseminated FBL-3 by treatment with 180 mg/kg cyclophosphamide (CY) and adoptively transferred Lyt-1+,2- T cells obtained from congenic B6/Thy-1.1 donors immune to FBL-3. Analysis of the T cell compartment of ATXBM hosts treated and rendered tumor-free by this therapy revealed that the only T cells present in the mice were donor-derived Lyt-1+,2- T cells. In vitro stimulation of these T cells with FBL-3 tumor cells, which express class I but no class II major histocompatibility complex antigens, induced lymphokine secretion, but did not result in the generation of cytotoxic T lymphocytes (CTL). Thus, in a setting in which mice lack Lyt-2+ T cells, and in which no CTL of either host or donor origin could be detected, immune Lyt-1+,2- T cells, in conjunction with CY, mediated eradication of a disseminated leukemia. The results suggest that delayed-type hypersensitivity responses induced by immune T cells represent a potentially useful effector mechanism for in vivo elimination of disseminated tumor cells.

Animals↗
PubMed1985

Interleukin 2 (IL 2) administered in vivo: influence of IL 2 route and timing on T cell growth.

The influence of the route and the frequency of IL 2 administration on the ability of IL 2 to induce the growth of activated T cells in vivo was evaluated. Initial pharmacokinetic studies confirmed that i.v. injection of IL 2 results in a relatively high peak serum concentration, but a short serum half-life. By contrast, i.p. or subcutaneous (s.c.) injection of IL 2 results in a lower peak concentration but a prolonged serum half-life. The bioavailability of IL 2 administered by these routes was assessed by measuring the in vivo growth of adoptively transferred T cells that had been previously cultured long-term with IL 2, because the growth of such cells in vivo has been shown to be proportional to the dose of IL 2 administered. The results demonstrated that i.p., s.c., or i.v. administration of IL 2 each resulted in marked donor T cell growth in vivo. Thus, IL 2 can function in vivo at sites distant to the sites of injection. In addition, the magnitude of T cell growth in vivo varied dependent on the route of IL 2 administration and correlated with the length of time IL 2 was detectable in serum, rather than the peak level achieved (i.e., IL 2 inoculated i.v. had the highest peak concentration but was least effective). As suggested by these findings, dividing the total dose of IL 2 into frequent low-dose injections was more effective in inducing T cell growth in vivo than was dividing the total dose of IL 2 into less frequent higher-dose injections. These studies confirm the great potential for IL 2 to induce the growth of activated of T cells in vivo and demonstrate that the rate of T cell growth reflects not only the dose but also the route and timing of IL 2 administration.

Animals↗
PubMed1984

Interleukin-2 administered in vivo induces the growth and augments the function of cultured T cells in vivo.

The purpose of the studies being described was to determine if interleukin-2 (IL-2) administered in vivo can induce the growth and increase the number of antigen-activated T cells, and thereby augment specific T cell function in vivo. Initial experiments examined the in vivo growth of adoptively transferred T cells previously cultured long term with IL-2, since in vitro such long-term cultured T cells are exquisitely dependent on exogenous IL-2 for proliferation and survival. To identify and quantify donor T cells in vivo, experiments were performed with donor and host mice congenic for the T cell marker Thy 1. Host mice receiving congenic long-term cultured immune T cells were inoculated daily with purified IL-2 beginning on the day of cell transfer, and donor T cells within host ascites, spleen, and lymph nodes were enumerated at selected points in time. The experiments demonstrated that exogenous IL-2 induced in vivo growth of long-term cultured T cells proportional to the dose of IL-2 administered. Similar IL-2 regimens induced the in vivo growth and augmented the function of donor T cells that had been activated to express IL-2 receptors in vitro by 5-day culture with antigen but had not been cultured with exogenous IL-2. Thus, prior adaptation to growth with exogenous IL-2 in vitro is not necessary to render T cells responsive to IL-2 in vivo. In contrast to long-term cultured T cells in vivo (which died rapidly in vivo without exogenous IL-2), noncultured donor T cells proliferated in vivo in response to antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Relationship between in vivo mitomycin C exposure, sister chromatid exchange induction and in vitro mitogenic proliferation. I. Development of murine splenic cell system.

In vivo administration of mitomycin C (MMC) to C57BL/6J mice induced a rapid, initial suppression (24 hours post injection) of in vitro mitogenesis. This was followed by of the mitogen concentration-response curves were found of the three mitogens, phytohemagglutinin and concanavalin A, but not for lipopolysaccharide. By 144 hours post injection, the dose-response curves and magnitude of the responses had returned to approximately control (untreated) levels. This approach provides a model system for the functional assessment of in vivo cellular damage by MMC.

Animals↗
PubMed1981

Relationship between in vivo mitomycin C exposure, sister chromatid exchange induction and in vitro mitogenic proliferation. II. Effect of aging on spleen cell mitogenesis and sister chromatid exchange induction.

In vivo administration of mitomycin C (MMC) produces an increase in both the frequencies of sister chromatid exchange (SCE) as well as inhibition of in vitro mitogenic responses. At low concentrations of MMC (2 mg/kg) spleen cell suspensions from both young and old mice showed similar patterns of mitogen inhibition and increased SCE frequencies. At high MMC concentrations (5 mg/kg) significant differences between young and old responses were observed. Spleen cells from young animals displayed mitogen-inhibition curves which plateaued with increasing doses of MMC, while the cells from old animals displayed a continuing increase in mitogenic inhibition. MMC-induced SCE frequencies revealed a complementary pattern: increasing SCE frequencies as a function of MMC concentration in young spleen cells while SCE levels plateaued in old spleen cell populations. The results of these studies suggest (1) that an inverse relationship exists between sister chromatid exchange induction and mitogenic response, (2) that cells from older animals may have an increased sensitivity to high levels of DNA damage (5 mg/kg MMC), and (3) that this sensitivity may be expressed functionally by increased inhibition of in vitro mitogenic responses.

Aging↗
PubMed1981

Physician influence on patient compliance: a clinical trial.

This study was designed to measure the effect of altering three possible impediments to care provided patients with non-emergency problems in a large city hospital emergency department: inadequate patient education by physician, lack of continuity of care, and complex and impersonal clerical procedures. Patients with symptomatic urinary tract infections were randomly assigned to intervention and control groups. A senior physician spent extra time with patients in the intervention group to discuss the assessment and management of their problem, bypass the usual clerical procedures at discharge, and promise continuity of care. Patients in the control group were treated in the usual fashion by emergency department nurses and residents. The return rate to the emergency department three weeks after the initial visit was used to measure the effect of the altered care applied to patients in the intervention group. Our hypothesis was that patients in the intervention group would be more likely to return. Of 46 patients in the intervention group 26 returned. Of 43 patients in the control group, 14 returned (chi square 4.23 after Yate's correction, 0.025 less than P less than 0.05). The significance of this improvement is discussed.

Clinical Trials as Topic↗
PubMed1981

The role of interleukin-2 (IL-2) in the differentiatin of cytotoxic T cells: the effect of monoclonal anti-IL-2 antibody and absorption with IL-2 dependent T cell lines.

A variety of approaches, including the use of a monoclonal antibody, have indicated that the lymphokine Interleukin 2 is a necessary and sufficient mediator for initiating cytotoxic T cell differentiation in vitro. Mitogen (Con A, PHA) stimulation of spleen cells and K/D or I region stimulation in primary MLC all led to IL-2 production, as measured by the growth of an IL-2 dependent T cell clone, and to the production of a "helper" factor necessary for cytotoxic T lymphocyte (CTL) differentiation against metabolically inactivated stimulator spleen cells. Several lines of evidence suggested that the IL-2 activity and CTL "helper" activity were due to a single molecular entity. These included the observations that: i) There was a linear relationship (R = 0.99) between IL-2 activity and relative CTL "helper" activity regardless of the preparation used (purified IL-2; MLC, or mitogen-induced supernatants). ii) Absorption of MLC supernatants with T cell "blasts" or with IL-2 dependent T cell lines concomitantly removed both IL-2 and CTL "helper" activities. iii) IL-2 activity purified by isoelectric focusing, or by polyacrylamide gel electrophoresis, displayed CTL "helper" activity. iv) Both CTL "helper" and IL-2 activities were neutralized by a monoclonal antibody directed against IL-2.

Absorption↗