Chimeric interleukin 2 receptor alpha chain antibody derivatives with fused mu and gamma chains permit improved recruitment of effector functions

In order to investigate the feasibility of shuffling effector functions of monoclonal antibodies, we constructed chimeric antibodies with fused heavy chains. The derivatives studied are based on a monoclonal antibody directed against the alpha chain of the human Il2-R. Derivatives studied were the IgG1 and IgM isotypes; IgM delta, lacking the ability of multimerization due to a deletion; IgMc gamma 1 and IgGlc mu, with fused mu and gamma 1 chains and vice versa. IgG1, IgM delta and IgMc gamma 1 were secreted as monomers, IgM and IgG1c mu as polymers. The Ki values for competition with radio-iodinated Il2 with respect to binding to the Il2-R were markedly lower for polymeric than for monomeric derivatives (300-400 pM versus 2500-6500 pM). Recruitment of complement mediated by the deposition of C3 fragments, either of heterologous (rabbit) or homologous (human) origin, was mediated only by the polymeric derivatives IgM and IgG1c mu. ADCC was mediated by monomeric IgG1 and polymeric IgG1c mu, the latter derivative being active at concentrations 100-fold lower than the former. Together, the results demonstrate that both CDC and ADCC effector functions can be combined on a polymeric antibody derivative with fused gamma 1 and mu chains. In addition, such a derivative, due to its polymeric nature, has a high binding affinity. These properties may be important for the elimination of target cells in vivo.

Gene transfer of the interleukin (IL)-2 receptor beta chain into an IL-7-dependent pre-B cell line permits IL-2-driven proliferation: tyrosine phosphorylation of Shc is induced by IL-2 but not IL-7

Expression of the interleukin (IL)-2 receptor beta chain in the IL-7-dependent pre-B cell line IxN/2B permitted growth in presence of either IL-2 or IL-7, allowing for a direct comparison of intracellular signaling events. Protein tyrosine phosphorylation was essential for IL-2 and IL-7-induced signal transduction since the tyrosine kinase inhibitor herbimycin A blocked proliferation in response to both factors. Western blot analysis of tyrosine-phosphorylated proteins revealed that both IL-2 and IL-7 stimulation led to enhanced phosphorylation of proteins of 170-, 145-, 115- and 99-kDa, as well as induction of phosphorylation of a 96-kDa protein. However, a 55- and a 155-kDa protein were only phosphorylated after IL-2 stimulation. The 55-kDa protein specifically phosphorylated by IL-2 could be identified as p52shc which has recently been shown to be critically involved in Ras activation. Shc tyrosine phosphorylation as a result of IL-2 stimulation was consistently found in CTLL-2 cells and human T lymphoblasts. Taken together our results indicate that the IL-2- and IL-7-stimulated intracellular pathways are partially different and that Shc is a target of IL-2-, but not IL-7-, stimulated tyrosine phosphorylation.

Tyrosine phosphorylation of Shc is induced by IL-3, IL-5 and GM-CSF

The receptors for IL-3, IL-5 and GM-CSF belong to the hematopoietic receptor superfamily and have no intrinsic tyrosine kinase activity but nevertheless indirectly induce protein tyrosine phosphorylation. In order to directly compare the effects of IL-3, IL-5 and GM-CSF on protein tyrosine phosphorylation we analyzed the murine cell line FDCP-1 which proliferates equally well in response to IL-3 and GM-CSF and the cell line B13 which responds to both IL-3 and IL-5. The protein tyrosine phosphorylation pattern induced by IL-3, IL-5 and GM-CSF in these cell lines was shown to be remarkably similar and all three cytokines induced tyrosine phosphorylation of Shc, a src homology domain-2 containing protein which has been shown to be involved in Ras activation by tyrosine kinase receptors.

Tumor-cell-targeted cytokine gene transfer in experimental models for cancer therapy

The genetic manipulation of tumor cells to express immunostimulatory molecules provides a current approach for the analysis of immune reactions against tumor cells in vivo. Experiments with multiple cytokines have demonstrated that an array of different host effector cells can be recruited by different cytokines in vivo, but more studies are necessary to distinguish cytokine-specific effects from as yet uncharacterized influences of different tumor models. A technically feasible clinical application of this approach is to be seen in the generation of vaccines by introducing such immunostimulatory genes into cancer cells and boosting systemic immune reactions against the unmodified cells. The experimental basis of these vaccination studies is critically discussed.

A sialyl-Le(x)-negative melanoma cell line binds to E-selectin but not to P-selectin

The adhesion molecules E-selectin (ELAM-1) and P-selectin (GMP-140/CD62) recognize the carbohydrate motives sialyl-Le(x), sialyl-diLe(x), or sialyl-Lea, though with different affinity. We found that the melanoma cell line NKI-4 bound to E-selectin, but not to P-selectin. This melanoma cell line did not express sialyl-Le(x), but was positive for sialyl-diLe(x) and sialyl-Le(a). In contrast, 2 other melanoma cell lines, MeWo and SK-MEL-28, expressing either sialyl-diLe(x) or sialyl-Le(a) on the cell surface, bound neither E-selectin nor P-selectin. Transfection of the fucosyltransferases Fuc-TIII, Fuc-TIV, and Fuc-TV mediates cell surface expression of sialyl-Le(x) in many cell lines. We detected transcripts of the fucosyltransferases Fuc-TIII and Fuc-TV in 4 melanoma cell lines despite the absence of cell surface sialyl-Le(x). Our observations indicate that expression of fucosyltransferases (Fuc-TIII and -TV) and generation of cell-surface sialyl-diLe(x) are not sufficient to permit adherence to E-selectin or P-selectin. Furthermore, it seems possible that a yet undefined ligand different from sialyl-Le(x), sialyl-diLe(x), or sialyl-Le(a) enables melanoma cells to adhere to E-selectin.

T cells bind to the endothelial adhesion molecule GMP-140 (P-selectin)

A crucial step in an effective immune response is the adhesion of circulating lymphocytes. Lymphocytes must attach to endothelial cells before they can migrate into the graft. It has been shown that T cells bind to ICAM-1 and VCAM-1. Additionally, certain T cell subsets bind to ELAM-1. We now report that resting CD4+ and CD8+ T cells as well as individual CD4+ T cell clones and CD8+ T cell lines bind to GMP-140 in an adhesion assay using protein chimeras consisting of the extracellular domain of GMP-140 linked to the hinge domain of human IgG1. Whereas resting T cells bound similarly to ELAM-1 IgG and GMP-140 IgG, activated T cells represented by CD4+ T cell clones and CD8+ T cell lines bound to GMP-140 IgG, but not to ELAM-1 IgG. Neither the binding to immobilized GMP-140 IgG, nor to immobilized ELAM-1 IgG could provide T cells with costimulatory signals for proliferation in the presence of submitogenic concentrations of anti-CD3 antibodies. The binding of T cells to the endothelial adhesion receptor GMP-140 might be important during the initial adhesion process of lymphocytes in rejecting grafts.

Expression of tumor necrosis factor by different tumor cell lines results either in tumor suppression or augmented metastasis

Tumor necrosis factor (TNF) produced by tumor cells after gene transfer can effectively suppress the growth of locally growing tumors. We wanted to test the effects of "local" TNF on the growth of a highly metastatic cell line. Therefore, a recombinant retrovirus allowing expression of the TNF gene by the beta-actin promotor has been constructed and used to infect the two tumor cell lines EB and ESB, which grow as solid tumor or metastasize, respectively. Expression of TNF by EB cells resulted in their rapid and dose-dependent rejection. In sharp contrast, mice injected with ESB cells producing similar amounts of TNF showed no signs of tumor suppression, but rather had reduced survival rates that correlated with enhanced hepatic metastases. The accelerated formation of liver metastases by ESB TNF cells could be reversed by an anti-TNF mAb. These results demonstrate the opposite effects TNF may have on tumor growth: suppression of a locally growing tumor and promotion of metastasis formation.

Mechanisms of rejection induced by tumor cell-targeted gene transfer of interleukin 2, interleukin 4, interleukin 7, tumor necrosis factor, or interferon gamma

Interleukin (IL)-2, IL-4, IL-7, tumor necrosis factor (TNF), or interferon-gamma (IFN-gamma) has been shown to be able to induce tumor rejection if produced locally by the tumor cells after gene transfer. To analyze whether the cellular rejection mechanisms are different or redundant we have expressed the cytokines in the same tumor cell line (J558L). Cell depletion experiments revealed that all cytokines required CD8+ T cells for complete long-term tumor eradication, although effective but transient host-dependent tumor suppression was also observed in the complete absence of CD8+ T cells. The transient tumor suppression induced by IL-2, IL-4, TNF, or IFN-gamma was also operative in nude and severe combined immunodeficient mice, whereas only tumor suppression induced by IL-7 was dependent on the presence of CD4+ T cells and was not evident in nude mice. The T-cell-independent effector arm of IL-2 and IFN-gamma but not IL-4 and TNF was mediated in part by natural killer cells. The transience of tumor suppression in the absence of T cells reflected loss of cytokine production in the case of TNF, IL-2, and IL-4 but not IFN-gamma. Immunohistologic analysis revealed all cytokine-producing tumors to be heavily infiltrated by macrophages. IL-4 and IL-7 tumors additionally contained eosinophils. The infiltration by T cells did not necessarily reflect their contribution to tumor rejection. Thus, the different cytokines activate heterogeneous transient tumor-suppressive mechanisms but always require CD8+ T cells for complete tumor rejection.

Vaccinations with tumor cells genetically engineered to produce different cytokines: effectivity not superior to a classical adjuvant

The potential of tumor cells (J558L) engineered to produce one of 5 different cytokines (interleukin 2, interleukin 4, interleukin 7, tumor necrosis factor, or gamma-interferon) to give rise to systemic immunity protective against a contralateral challenge with the parental cells was analyzed. The rejection of all cytokine-producing cells appeared to induce some systemic response capable of mediating the rejection of low numbers of subsequently contralaterally injected cells, but the effect was much less obvious with higher cell numbers. The injection of any possible combination of two of the cytokine producers did not reveal any synergistic effects. The cytokine gene-transfected tumor cells were not superior to the parental cells admixed with the adjuvant Corynebacterium parvum with respect to their potential as immunogens to induce immunity.

Macrophage colony-stimulating factor gene transfer into tumor cells induces macrophage infiltration but not tumor suppression

In order to analyze the effect of a high local concentration of macrophage colony-stimulating factor (M-CSF; CSF-1) on tumor growth, the plasmacytoma cell line J558L was transfected with the human M-CSF gene and injected into syngeneic BALB/c mice. In contrast to the parental tumors, M-CSF transfectants were heavily infiltrated by macrophages as evidenced by immunohistochemistry with antibodies to Mac-1 and Mac-3 and by isolation of the macrophages from the tumor. Nevertheless, tumor growth was only slightly affected by M-CSF and M-CSF-producing cells grew as tumor in all cases. The growth retardation of M-CSF-producing cells varied depending on the experiment and seemed to be due to an indirect effect because the growth rate of the cells in vitro had not changed upon gene transfer. Attempts to activate the tumor-infiltrating macrophages for tumor suppression by systemic application of interferon-gamma and/or lipopolysaccharide were not successful. Altogether, our results suggest that M-CSF is a potent chemoattractant for macrophages in vivo but alone is not sufficient to activate these macrophages for tumoricidal activity.

Interleukin-4-mediated tumor suppression in nude mice involves interferon-gamma

The molecular events during the anti-tumor response induced by interleukin (IL)-4 were investigated by quantitative polymerase chain reaction. The growth of Chinese hamster ovary cells transfected to produce IL-4 (CHO.T1) was strongly suppressed when cells were injected intraperitoneally into nude mice and this suppression was accompanied by the rapid accumulation of activated macrophages. Peritoneal cells from such mice were analyzed for mRNA induced by IL-4. Correlating with a high local IL-4 concentration, several transcripts were found to be up-regulated during the early phase of the anti-tumor response [IL-4 receptor, IL-5, tumor necrosis factor (TNF) and interferon (IFN)-gamma]. The functional relevance of the elevated mRNA levels was analyzed by injection of CHO.T1 cells together with anti-cytokine monoclonal antibodies (mAb). In contrast to anti-IL-5 and anti-TNF mAb, an anti-IFN-gamma mAb interfered with the anti-tumor response demonstrating the involvement of IFN-gamma during the IL-4-induced tumor suppression. Tumor growth in anti-IFN-gamma mAb-treated animals was significantly delayed in comparison to anti-IL-4 mAb-treated mice, suggesting that IFN-gamma-independent effector cells may also be involved.

Interleukin 7 induces CD4+ T cell-dependent tumor rejection

The potential of interleukin 7 (IL-7) to induce an antitumor response in vivo was analyzed. Therefore, the IL-7 gene was expressed in the plasmacytoma cell line J558L. Although the growth of IL-7-producing cells was not retarded in vitro, the IL-7-producing cells were completely rejected upon injection into mice. Tumor rejection was observed only in syngeneic but not in nude mice. The tumor-suppressive effect could be abolished by the parallel injection of an anti-IL-7 monoclonal antibody. Immunohistochemical analysis revealed IL-7-dependent infiltration of the tumor tissue by CD4+ and CD8+ T lymphocytes, and also type 3 complement receptor-positive (CR3+) cells, predominantly macrophages. Depletion of T cell subsets in tumor-bearing mice showed the absolute dependence of the antitumor response on CD4+ cells, whereas tumor rejection was unaffected by depletion of CD8+ cells. In addition to CD4+ cells, CR3+ cells were also needed for tumor rejection. The antitumor effect of IL-7 was confirmed by expression of the IL-7 gene in a second tumor cell line of different cellular origin. Together, our results demonstrate that a high local IL-7 concentration at the tumor site obtained by tumor cell-targeted gene transfer leads to tumor rejection involving a cellular mechanism that seems to be different from the ones observed in analogous experiments with other cytokines.

Synthesis and functional characterization of a recombinant monoclonal antibody directed against the alpha-chain of the human interleukin-2 receptor

We have determined the sequence of the light and heavy chains of mAb 3G-10 (IgG1), a monoclonal antibody competing with interleukin 2 (IL2) for binding to the human IL2 receptor Tac protein. The antibody-encoding genes were chimerized by introducing splice donor and part of the intron sequences into the cDNA and subsequently linking it to the constant parts of the human IgG1 gene. The chimeric mAb was produced in mouse myeloma cells and purified. Murine and chimeric mAbs showed similar properties with respect to inhibition of T-cell proliferation. In contrast to its murine counterpart, the chimeric mAb exhibited Ab-dependent cellular cytotoxicity and, when combined with an Ab recognizing a different epitope on the IL2 receptor Tac protein, was able to activate human complement. The chimerized mAb might therefore have improved therapeutic efficacy.

Limited proteolysis of HMW kininogen by plasma kallikrein in man--evidence for a processing mechanism different from the bovine system

The limited proteolysis of human HMW kininogen by plasma kallikrein has been studied. Kallikrein liberated bradykinin from HMW kininogen (Mr 114 kDa) and generated a two-chain molecule with a heavy chain of Mr 63 kDa and a light chain of Mr 58 kDa interconnected via a single disulfide bridge. As proteolysis proceeded, a step-wise processing of the initially formed light chain occurred giving rise to modified light chains of Mr 45 and 41 kDa. Sequence analysis indicated that two polypeptides had been cleaved from the amino- and carboxy-terminal parts of the 58 kDa light chain. Major part of the histidine-rich peptide which is critical to surface binding of HMW kininogen was kept in the shortened light chains. These findings are consistent with the observation that trimming of the human HMW kininogen does not abolish its procoagulant activity. By contrast, the bovine HMW kininogen is inactivated due to removal of the entire histidine-rich peptide. Hence, the proteolytic processing mechanisms for HMW kininogen are distinct in the human and the bovine contact phase activation systems.

Amikacin sulfate in the cat: Serum, urine and uterine tissue concentrations

Puerperal metritis and pyometra in non-breeding cats is frequently caused by gram-negative bacteria that are resistant to a variety of antibiotics. Amikacin has been found to be effective against pathogens associated with uterine infections in the mare and the woman, but its efficacy has not been studied in the cat. Serum concentrations of amikacin were determined in healthy adult cats (six male and six female) after administration of 5, 10, and 20 mg/kg body weight of amikacin sulfate, each dose given subcutaneously (s.c.), intramuscularly (i.m.) and intravenously (i.v.) to each of the cats using a repeat treatment design. In a subsequent experiment, the six females were given 10 mg/kg s.c. amikacin and samples of blood, urine and full-thickness uterine wall were taken at 40 and 120 minutes after treatment. Mean serum concentrations of amikacin peaked between 30 and 45 minutes after i.m. injection and between 45 and 60 minutes after s.c. injections. The serum amikacin concentration curves were similar regardless of dose or administration route except for a slightly longer retention time after the 20 mg/kg dose given i.m. and s.c. After s.c. injection of 10 mg/kg, the mean uterine concentration of amikacin at two hours after treatment was 4.1 ug/g; the concurrent mean serum concentration was 18.6 ug/ml.

[Tumours of the pineal region: Part II: results of treatment in 23 patients (author's transl)]

The outcome of 23 patients with tumours in the pineal region was investigated following treatment with shunting, irradiation, extirpation or with a combination of these three procedures. The choice of therapy is difficult because in most cases the kind of tumour is unknown. The irradiation of radioresistant lesions however causes an unnecessary injury of the surrounding tissue whereas the trial of extirpation of a radiosensitive tumour exposes the patient to an unnecessary danger. After the results of therapy a method of treatment is proposed.

[Tumors of the pineal region. Part I: neurologic and neuroradiologic symptoms in 23 patients]

After a short anatomical review about the neighbourhood of the lamina quadrigemina 23 patients with different processes in the pineal region were investigated with regard to their neurological symptoms and radiological findings. Symptoms of the eyes in conjunction with signs of elevated intracranial pressure in most of the cases show the way to the diagnosis which will be completed by ventriculography, angiography, and recently by computer tomography with regard to the expansion of the process; any prediction about the kind of tumour is possible only in a little percentage.