Possible relationships between in vivo antitumour activity and toxicity of tumour necrosis factor-alpha

The discoveries of a tumour necrosis-inducing substance in sera of experimental mice and of cytotoxic factor(s) in cultures of stimulated lymphoid cells triggered intense research efforts which have culminated in the production of two distinct but related recombinant materials, human tumour necrosis factors TNF-alpha (cachectin) and TNF-beta (lymphotoxin). The necrosis of tumours by TNF is but one feature of high doses of these immune system hormones that possess numerous biological activities. Apart from their direct cytotoxic/cytostatic activities against tumours in vitro and in vivo, the in vivo antitumour activities of TNF-alpha or TNF-beta may involve the following biological activities: the induction of interleukin 1 production; activation of polymorphonuclear neutrophil functions; modulation of endothelial cell functions; and augmentation of specific immune functions. Many of these activities are associated with an irreversible acute inflammation which appears to be the immediate lethal effect of TNF on transplantable tumours in mice. This inflammation leads to thrombosis, disruption of the tumour's blood supply and, finally, tumour death. Inflammatory effects of high doses of TNF are also seen in the rodent gastrointestinal tract but here the inflammation seems to be reversible.

Expression of single-chain Fv-Fc fusions in Pichia pastoris

Phage display technology makes possible the direct isolation of monovalent single-chain Fv antibody fragments. For many applications, however, it is useful to restore Fc mediated antibody functions such as avidity, effector functions and a prolonged serum half-life. We have constructed vectors for the convenient, rapid expression of a single-chain antibody Fv domain (scFv) fused to the Fc portion of human IgG1 in the methylotrophic yeast Pichia pastoris. The scFv-Fc fusion protein is secreted and recovered from the culture medium as a disulfide-linked, glycosylated homodimer. The increased size of the dimer (approximately 106 kDa vs. approximately 25 kDa for a scFv) results in a prolonged serum half-life in vivo, with t(1/2) of the beta phase of clearance increasing from 3.5 h for a typical scFv to 93 h for a scFv-Fc fusion in mice. The scFv-Fc fusion is capable of mediating antibody-dependent cellular cytotoxicity against tumor target cells using human peripheral blood mononuclear cells as effectors. Finally, the Fc domain is a convenient, robust affinity handle for purification and immunochemical applications, eliminating the need for proteolytically sensitive epitope and/or affinity tags on the scFv.

186Re-labeled antibodies to p185HER2 as HER2-targeted radioimmunopharmaceutical agents: comparison of physical and biological characteristics with 125I and 131I-labeled counterparts

Overexpression of the HER2/neu protooncogene has been shown to correlate with poor clinical prognosis. A murine monoclonal antibody (4D5) directed against the extracellular domain (ECD) of p185HER2 has been shown to inhibit in vitro and in vivo growth of carcinomas overexpressing HER2 and has been humanized (rhuMAb HER2). The objective of the study was the identification of an agent which might be useful for in vitro studies, tumor imaging and/or radioimmunotherapy by linking beta-emitting radionuclides to these HER2-targeted antibodies. Murine 4D5 and humanized rhuMAb HER2 were radiolabeled with 125I, 131I or 186Re. Physical characteristics (TCA precipitability, SDS-PAGE, size exclusion chromatography), binding affinities to the HER2 ECD (in an ELISA and on SK-BR-3 cells) and antiproliferative activities of the radiolabeled antibodies were determined. Although 131I-4D5 and 131I-rhuMAb HER2 usually retained > 85% ECD binding, they exhibited increased aggregation and fragment content, drastically reduced antiproliferative activities and poor stability upon storage at 4 degrees C. For these antibody preparations, conservation of binding did not necessarily correlate with preservation of bioactivity indicating the importance of bioactivity determinations in radiolabeled antibody studies. Conversely, 4D5 and rhuMAb HER2 labeled with 125I or 186Re maintained physical properties, ECD binding, antiproliferative activities and were stable upon storage at 4 degrees C for at least 8 days. The superior retention of physical and biological characteristics of 186Re-labeled 4D5 and rhuMAb HER2 compared with their 131I-labeled counterparts suggests the potential for their use as radioimaging and radioimmunotherapeutic agents in the treatment of HER2 overexpressing tumors.

Bispecific HER2 x CD3 antibodies enhance T-cell cytotoxicity in vitro and localize to HER2-overexpressing xenografts in nude mice

Recently, we reported the development of fully humanized bispecific F(ab')2 antibodies with dual binding specificities to human T-lymphocytes and to tumor cells overexpressing HER2. These antibodies were shown to effectively mediate targeted HER2-overexpressing tumor cell killing by freshly isolated human T-cells. In this report we extend our studies to describe the interaction of the bispecific antibody with activated T-lymphocytes (ATL) maintained in culture for an extended period of time. A microtiter plate radioreceptor assay was used to elucidate the affinity of bispecific antibody binding to ATL. The data show that ATL maintained in vitro for up to 5 weeks continued to express high-affinity CD3 surface markers that bound to bispecific antibody with a Kd of 2.49 nM and exerted cytolytic activities against targets overexpressing HER2. In addition, we demonstrated the specific localization of HER2 x CD3 bispecific antibody to HER2-overexpressing tumor xenografts in nude mice. Furthermore, HER2 x CD3 bispecific antibody has the ability to inhibit the proliferative activities of breast tumor (SKBR-3) cells in vitro. The clinical implications of these data are discussed.

Butylated hydroxyanisole specifically inhibits tumor necrosis factor-induced cytotoxicity and growth enhancement

The effect of commonly used food antioxidants on recombinant tumor necrosis factor alpha (rTNF-alpha)-induced cytotoxicity, growth enhancement and adhesion has been evaluated. Butylated hydroxyanisole (BHA) and 4-hydroxymethyl-2,6-di-t-butylphenol (HBP) were the only two of nine antioxidants that completely inhibited rTNF-alpha-induced cytotoxicity in L929 and WEHI 164 fibrosarcoma cells. Ethoxyquin, propyl gallate and butylated hydroquinone only partially inhibited rTNF-alpha-induced cytotoxicity, while the antioxidants butylated hydroxytoluene (BHT), alpha-tocopherol, ascorbic acid and thiodipropionic acid had minimal effects. The only difference between the molecular structure of the efficient HBP and the non-efficient BHT, is a hydroxymethyl group instead of a hydroxyl group on the phenolic ring. Neither BHA nor BHT inhibited the activation of NF kappa B after 10 or 60 min challenge with rTNF-alpha in L929 cells. BHA also inhibited rTNF-alpha-induced, but not rIL-1 beta-induced growth enhancement in FS-4 fibroblasts. Further, BHA blocked both rTNF-alpha-induced and rIL-1 beta-induced prostaglandin E2 synthesis in FS-4 fibroblasts. BHA inhibited the rTNF-alpha-induced release of arachidonic acid in both FS-4 and L929 cells, suggesting that BHA inhibits cellular phospholipase(s). Neither alpha-tocopherol nor BHA inhibited rTNF-alpha-induced adhesiveness of human endothelial cells. The results indicate that BHA is a specific and potent inhibitor of rTNF-alpha- and rTNF-beta-induced cytotoxicity, as well as of rTNF-alpha-induced growth enhancement.

Development of humanized bispecific antibodies reactive with cytotoxic lymphocytes and tumor cells overexpressing the HER2 protooncogene

The HER2 protooncogene encodes a 185-kD transmembrane phosphoglycoproteins, human epidermal growth factor receptor 2 (p185HER2), whose amplified expression on the cell surface can lead to malignant transformation. Overexpression of HER2/p185HER2 is strongly correlated with progression of human ovarian and breast carcinomas. Recent studies have shown that human T cells can be targeted with bispecific antibody to react against human tumor cells in vitro. We have developed a bispecific F(ab')2 antibody molecule consisting of a humanized arm with a specificity to p185HER2 linked to another arm derived from a murine anti-CD3 monoclonal antibody that we have cloned from UCHT1 hybridoma. The antigen-binding loops for the anti-CD3 were installed in the context of human variable region framework residues, thus forming a fully humanized BsF(ab')2 fragment. Additional variants were produced by replacement of amino acid residues located in light chain complementarity determining region 2 and heavy chain framework region 3 of the humanized anti-CD3 arm. Flow cytometry analysis showed that the bispecific F(ab')2 molecules can bind specifically to cells overexpressing p185HER2 and to normal human peripheral blood mononuclear cells bearing the CD3 surface marker. In additional experiments, the presence of bispecific F(ab')2 caused up to fourfold enhancement in the cytotoxic activities of human T cells against tumor cells overexpressing p185HER2 as determined by a 51Cr release assay. These bispecific molecules have a potential use as therapeutic agents for the treatment of cancer.

Cytokine-associated tissue injury and lethality in mice: a comparative study

A comparative study was performed to examine the lethal effects of several cytokines injected into mice sensitized with actinomycin D (Act-D). Consistent with published data, human tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) (0.2-5 micrograms) caused the death of the animals within 8-12 hr after injection. Human interleukin-6 (IL-6) and interleukin-8 (IL-8) (0.6-6 micrograms) known to be induced by TNF-alpha did not show any lethal effects, indicating that TNF-alpha-associated lethality is not mediated by IL-6 or IL-8. Human tumor necrosis factor-beta (TNF-beta) (also called lymphotoxin), which shares structural and functional properties with TNF-alpha, was as potent as TNF-alpha in its lethal effects. Murine interferon-gamma (IFN-gamma) (0.04-5 micrograms) was also tested and showed no lethal effects in this model. In addition, a synthetic peptide corresponding to amino acid residues 163-171 of IL-1 beta, and which has been shown to lack the inflammatory effects of IL-1 beta, also caused no lethality among Act-D sensitized mice. The pretreatment of mice with IL-6, IL-8, or IFN-gamma had no protective effects on TNF-alpha or IL-1 beta-induced lethality in contrast to the protection observed by a pretreatment with TNF-alpha/IL-1 beta themselves or with endotoxin. Histopathologic data showed that severe tissue injury in vital organs is associated with the rapid lethality among sensitized mice.

Binding and regulation of cellular functions by monoclonal antibodies against human tumor necrosis factor receptors

The present study was undertaken to further characterize the interaction of monoclonal antibodies (mAbs) against tumor necrosis factor (TNF) receptors with different targets, and to assess their ability to influence TNF effects on U937 and human endothelial cell (HEC) functions. Actions of recombinant TNF-alpha on U937 and HEC were effectively inhibited by Htr-5 and Utr-1, and to a greater extent by a combination of both mAbs. These observations indicate that TNF interaction with antigenically different components of membrane receptors (p55 and p75) represents a crucial step in transduction of signals for TNF toxicity against U937 and TNF activation of HEC functions.

Regulation of interleukin-2 and interleukin-6 production from T-cells: involvement of interleukin-1 beta and transforming growth factor-beta

The effect of recombinant (r) interleukin-1 beta (rIL-1 beta) and transforming growth factor-beta (TGF-beta) on the production of interleukin-2 (IL-2) and interleukin-6 (IL-6) from an antigen-specific (LBRM-33-1A5) and an antigen-nonspecific (EL-4-NOB-1) T-cell line was investigated. rIL-1 beta induced the production of IL-2 and IL-6 from EL-4-NOB-1 cells in a dose-related manner. The LBRM-33-1A5 cells required phytohemagglutinin (PHA) in addition to rIL-1 beta in order to produce IL-2 and IL-6. IL-2 production was found to precede IL-6 production in both cell lines. No IL-2 or IL-6 production was observed by adding r murine tumor necrosis factor-alpha or r murine interferon gamma to the cells. The presence of 1 ng/ml TGF-beta reduced IL-2 and IL-6 production from both T-cell lines by more than 80%. The inhibition of IL-2 and IL-6 production was still evident by a concentration as low as 10 pg/ml of TGF-beta. rIL-1 beta and PHA also stimulated murine thymocytes to produce IL-6 which was inhibited up to 85% in the presence of 1 ng/ml TGF-beta. Taken together these results suggest that TGF-beta may suppress immune responses by inhibiting the endogenous production of IL-2 and IL-6.

Endotoxin, tumor necrosis factor-alpha and interleukin 1 induce interleukin 6 production in vivo

The ability of Escherichia coli-derived lipopolysaccharide (LPS), recombinant (r) interleukin 1-beta (rIL-1 beta), and r murine tumor necrosis factor-alpha (rMuTNF-alpha) to induce interleukin 6 (IL-6) production in vivo was investigated. Peak serum IL-6 concentration was attained after 2 hr of LPS injection into mice. The coinjection of antiserum against rMuTNF-alpha with LPS resulted in a reduction of the induced serum IL-6 level, indicating the involvement of endogenous TNF-alpha in LPS induction of IL-6. Recombinant IL-1 beta and rMuTNF-alpha injected directly caused the production of substantial amounts of IL-6 within 30 min. The injection of a combination of rIL-1 beta and rTNF-alpha induced a significantly greater level of IL-6 than either agent alone. The greater level of serum IL-6 was associated with hypothermia and an increased lethality among mice injected with both cytokines. These data demonstrate the abilities of IL-1 beta and TNF-alpha to induce IL-6 production in vivo and indicate that LPS induction of IL-6 may be mediated, at least partially, through TNF-alpha action. The data describe a new in vivo biologic activity shared between IL-1 beta and TNF-alpha and suggest that IL-6 may be an important effector in the manifestation of TNF-alpha and IL-1 beta actions in vivo.

Tumor necrosis factor-alpha-associated uterine endothelial injury in vivo. Influence of dietary fat

The influence of dietary fat on recombinant human tumor necrosis factor-alpha (rHuTNF-alpha)-associated vascular endothelial injury in mice was examined. Histopathologic evaluation showed that greater injury was consistently observed in the uterus characterized by necrosis of endothelial cells lining small vessels in the endometrium and accompanied by multifocal hemorrhage and inflammatory cell accumulation. Mice fed standard animal diet, high corn oil diet, or high menhaden oil diet showed no differences in their susceptibility to the acute injury caused by rHuTNF-alpha injected alone or in combination with recombinant murine interferon-gamma. These results indicate that uterine endothelium may be a more sensitive target for rHuTNF-alpha-mediated endothelial injury and that high menhaden oil diet does not protect against tissue injury associated with the administration of rHuTNF-alpha alone or in combination with recombinant murine interferon-gamma.

Interleukin 4 induces selective production of interleukin 6 from normal human B lymphocytes

In this paper we have shown that extensively purified human B lymphocytes respond to IL-4 treatment with a marked production of IL-6. Addition of anti-mu potentiated the effect of IL-4 on IL-6 production. Other cytokines tested like TNF-alpha and-beta, IFN-gamma, IL-1, IL-2, and IL-5 did not induce IL-6 secretion when given to resting B cells. Although B cells generally also produced TNF-alpha and TNF-beta upon stimulation, IL-4 did not induce TNF secretion and seemingly had a specific effect on IL-6 production.

Cytokine regulation of interleukin 6 production by human endothelial cells

The influence of recombinant (r) human tumor necrosis factor alpha (rTNF-alpha), r human interleukin 1 beta (rIL-1 beta), and r human interferon gamma (rIFN-gamma) on the production of interleukin 6 (IL-6) by human endothelial cells (HEC) was investigated. The addition of 1-100 U/ml of either rTNF-alpha or rIL-1 beta to cultures of HEC monolayers caused a dose-related increase in IL-6 production as detected after 24 hr of incubation. In contrast to rIL-1 beta and rTNF-alpha, the use of up to 1000 U/ml of rIFN-gamma caused only a moderate increase in IL-6 production. However, significantly greater quantities of IL-6 were produced by HEC monolayers subjected to 1000 U/ml of rIFN-gamma in combination with 1-100 U/ml of rTNF-alpha. Furthermore, the addition of graded concentrations of human transforming growth factor beta (TGF-beta) to cultures resulted in a dose-related inhibition of rIL-1 beta- and rTNF-alpha-induced IL-6 production by HEC. The results demonstrate that rIL-1 beta and rTNF-alpha share the ability to stimulate HEC for production of IL-6 and indicate that TGF-beta may act as an immunosuppressive agent, at least partially, through its ability to inhibit the action of TNF-alpha and IL-1 on endothelial cells.

Prevention of the graft-versus-host reaction in newborn mice by antibodies to tumor necrosis factor-alpha

The influence of antibodies to recombinant murine tumor necrosis factor-alpha (anti-rMuTNF-alpha) on the development of the graft-versus-host reaction in vivo was investigated. This was done by evaluating the degree of splenomegaly in newborn BDF1 (B6xDBA/2) mice 10-11 days after injection of autologous BDF1 (controls) or semiallogeneic B6 (test) spleen cells. Splenomegaly, as reflected by the spleen index, among test BDF1 mice was 3-4-fold greater than the SI of control BDF1 mice. However, the treatment of test BDF1 mice with multiple injections of rabbit anti-rMuTNF-alpha antiserum resulted in a significant reduction in the SIs. In additional experiments, hamster monoclonal antibodies to rMuTNF-alpha were also shown to be effective in preventing the GVHR in vivo. Neither normal rabbit serum nor normal hamster IgG affected the GVHR in test BDF1 mice. These results indicate that TNF-alpha plays an important role in the development of the GVHR in vivo and suggest that antibodies, or other antagonists, to TNF-alpha may have potential use for the management of organ or tissue transplants.

Pharmacokinetics of recombinant murine interferon-gamma and human interferon-alpha A/D(Bgl) administered in concert and their influence on natural killer cell function in mice

The pharmacokinetics of recombinant murine interferon-gamma (rMuIFN-gamma) administered alone and in combination with recombinant hybrid human interferon-alpha (rHuIFN-alpha A/D-[Bgl]) were studied following intravenous (i.v.) and intramuscular (i.m.) injections into mice. The concomitant influence of these IFNs on splenic natural killer (NK) cell function was also examined. The coinjection of both IFNs did not affect the pharmacokinetics of either after i.v. administration. However, simultaneous injection of both IFNs i.m. does result in statistically significant changes in the serum concentrations of rHuIFN-alpha A/D(Bgl). The clinical benefits of the increased bioavailability of rHuIFN-alpha A/D(Bgl) are not apparent since NK cell enhancement after both IFNs were injected together was the same as that obtained after injection of rHuIFN-alpha A/D(Bgl) alone. NK cell enhancement after both IFNs were injected together was the same as that obtained after injection of rHuIFN-alpha A/D(Bgl) alone. Correspondingly, the coinjection of both IFNs did not affect the pharmacokinetics of either.

The involvement of human tumor necrosis factors-alpha and -beta in the mixed lymphocyte reaction

The influence of recombinant human TNF-alpha and -beta (rHuTNF-alpha and -beta) in a human mixed lymphocyte reaction (MLR) was investigated. The addition of 1000 U/ml of either cytokine at the initiation of culture caused up to a sixfold increase in [3H]thymidine incorporation by responder cells. Furthermore, it was found that endogenous HuTNF-alpha is produced after allogeneic cell interaction and can be detected in the MLR supernatant within 1 h of culture initiation. The results also show that, in the absence of exogenous HuTNF-alpha, antibodies to rHuTNF-alpha can cause a significant inhibition of the MLR. These observations indicate the importance of TNF-alpha in allogeneic cell interaction and raise considerations for the use of antibodies, or other antagonists, to TNF-alpha as regulators of disease states associated with cell-mediated immune reactions.

The involvement of human tumor necrosis factors-alpha and -beta in the mixed lymphocyte reaction

The influence of recombinant human TNF-alpha and -beta (rHuTNF-alpha and -beta) in a human mixed lymphocyte reaction (MLR) was investigated. The addition of 1000 U/ml of either cytokine at the initiation of culture caused up to a sixfold increase in [3H]thymidine incorporation by responder cells. Furthermore, it was found that endogenous HuTNF-alpha is produced after allogeneic cell interaction and can be detected in the MLR supernatant within 1 h of culture initiation. The results also show that, in the absence of exogenous HuTNF-alpha, antibodies to rHuTNF-alpha can cause a significant inhibition of the MLR. These observations indicate the importance of TNF-alpha in allogeneic cell interaction and raise considerations for the use of antibodies, or other antagonists, to TNF-alpha as regulators of disease states associated with cell-mediated immune reactions.

Amplified expression of the HER2/ERBB2 oncogene induces resistance to tumor necrosis factor alpha in NIH 3T3 cells

Functional characterization of oncogene products that induce cellular transformation has progressed rapidly in recent years. However, less is known about the mechanism(s) by which the transformed cells may escape destruction by host immune defenses and form tumors. A recently described oncogene that has an important association with aggressive human breast carcinoma is "HER2," for human epidermal growth factor receptor 2. The oncogene has also been called NGL and human c-erbB-2 (ERBB2). In this paper we show that amplification of HER2 oncogene expression can induce resistance of NIH 3T3 cells to the cytotoxic effects of recombinant tumor necrosis factor alpha (rTNF-alpha) or macrophages. Resistance is accompanied by an increased dissociation constant for rTNF-alpha binding to high-affinity receptors on the HER2-transformed NIH 3T3 cells. The resistance phenotype is independent of transformation since NIH 3T3 cells transformed by the activated human homologue of the Harvey-ras oncogene (HRAS) retain high-affinity binding sites for rTNF-alpha as well as sensitivity to its cytotoxic effects. These results suggest that HER2 may potentiate tumorigenesis by inducing tumor cell resistance to host defense mechanisms.

The effects of human immunodeficiency virus recombinant envelope glycoprotein on immune cell functions in vitro

The effect of human immunodeficiency virus (HIV) recombinant envelope glycoprotein 120 (rgp 120) on the functions of peripheral blood mononuclear cells (PBMC) in vitro was investigated. The results demonstrate that rgp 120 used at concentrations less than 1 microgram/ml has no significant effects on PBMC function in vitro. However, the addition of 1-20 micrograms/ml of rgp 120 significantly inhibits the tetanus toxoid-induced PBMC proliferative response in a dose-related manner as determined by [3H]thymidine incorporation. The data also show that rgp 120 (5 micrograms/ml) causes up to 70% reduction in the number of immunoglobulin G-secreting cells in pokeweed mitogen-stimulated PBMC cultures. Further, rgp 120 can selectively interact with the CD4a epitope of the CD4 helper cell membrane receptor. These results indicate that microgram per milliliter levels of rgp 120 can depress certain immune functions in vitro. The significance of these findings to the pathogenesis of immunodeficiency in HIV infection remains to be determined.

Inhibition of cytokine production by cyclosporin A and transforming growth factor beta

We investigated the ability of cyclosporin A (CsA) and transforming growth factor beta (TGF-beta) to modulate the production of TNF-alpha and TNF-beta and IFN-gamma by unseparated, nonadherent, and adherent PBMC. Treatment of unseparated PBMC with CsA resulted in a significant dose-dependent inhibition of all three cytokines ranging from greater than 90% inhibition for IFN-gamma and TNF-beta, to approximately 70% for TNF-alpha. Pretreatment of unseparated or nonadherent PBMC with TGF-beta inhibited the production of IFN-gamma by 60-70%. However, the inhibition of TNF-alpha and TNF-beta production by these cells was only minimally affected, and at 0.1-1 ng/ml TGF-beta could enhance TNF-alpha production by unseparated PBMC. In contrast, pretreatment of adherent PBMC with TGF-beta inhibited the production of TNF-alpha by approximately 60%. TGF-beta also inhibited both TNF-alpha production and tumor cell cytotoxicity mediated by murine peritoneal-derived macrophages. These observations indicate that the biological effects of CsA and TGF-beta on immune functions are of a wider range than previously reported.

Characterization of the antitumor activities of human tumor necrosis factor-alpha and the comparison with other cytokines: induction of tumor-specific immunity

We have investigated the in vitro and in vivo antitumor activities of recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) against Meth A sarcoma. Meth A sarcoma cells were found to a) be relatively insensitive in vitro to rHuTNF-alpha, and b) express low numbers of TNF-alpha receptors. Intraperitoneally implanted Meth A sarcoma was insensitive to the antitumor effects of rHuTNF-alpha. In contrast, rHuTNF-alpha was highly efficacious against subcutaneously implanted Meth A sarcoma. Biodistribution studies with 125I- or 3H-labeled rHuTNF-alpha demonstrated that, after intravenous administration, the majority of the labeled rHuTNF-alpha localized in the kidney, lungs, and liver. Only low levels of radiolabel were found in subcutaneous Meth A implants. These results support the in vitro data on the low number of TNF-alpha receptors on Meth A sarcoma cells. The ability of rHuTNF-alpha to induce regression of established (7 days) subcutaneous Meth A implants, positively correlated with the degree of both macroscopic and microscopic tumor necrosis. In addition, recombinant human tumor necrosis factor-beta (lymphotoxin) and recombinant murine tumor necrosis factor-alpha induced similar levels of necrosis. Other lymphokines with known antitumor activities, recombinant human interferon-gamma, murine interferon-gamma, and human interleukin 1 alpha, failed to induce detectable necrosis of Meth A sarcoma. Mice which had rejected subcutaneous Meth A sarcoma implants after rHuTNF-alpha treatment and which were later challenged subcutaneously with Meth A sarcoma or other noncross-reacting chemically induced sarcomas were found to be specifically immune to Meth A sarcoma. In addition, low levels of cytotoxic antibodies reactive to Meth A sarcoma were detected in the sera of 21 of 30 Meth A immune mice. Histological evaluation of the hemorrhagic tumor necrosis induced by rHuTNF-alpha suggests that the primary lesion is vascular, possibly directly on the endothelial cells. The mechanisms involved in the generation of specific cell-mediated antitumor immunity in this model are at present unknown.

Characterization of the antitumor activities of human tumor necrosis factor-alpha and the comparison with other cytokines: induction of tumor-specific immunity

We have investigated the in vitro and in vivo antitumor activities of recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) against Meth A sarcoma. Meth A sarcoma cells were found to a) be relatively insensitive in vitro to rHuTNF-alpha, and b) express low numbers of TNF-alpha receptors. Intraperitoneally implanted Meth A sarcoma was insensitive to the antitumor effects of rHuTNF-alpha. In contrast, rHuTNF-alpha was highly efficacious against subcutaneously implanted Meth A sarcoma. Biodistribution studies with 125I- or 3H-labeled rHuTNF-alpha demonstrated that, after intravenous administration, the majority of the labeled rHuTNF-alpha localized in the kidney, lungs, and liver. Only low levels of radiolabel were found in subcutaneous Meth A implants. These results support the in vitro data on the low number of TNF-alpha receptors on Meth A sarcoma cells. The ability of rHuTNF-alpha to induce regression of established (7 days) subcutaneous Meth A implants, positively correlated with the degree of both macroscopic and microscopic tumor necrosis. In addition, recombinant human tumor necrosis factor-beta (lymphotoxin) and recombinant murine tumor necrosis factor-alpha induced similar levels of necrosis. Other lymphokines with known antitumor activities, recombinant human interferon-gamma, murine interferon-gamma, and human interleukin 1 alpha, failed to induce detectable necrosis of Meth A sarcoma. Mice which had rejected subcutaneous Meth A sarcoma implants after rHuTNF-alpha treatment and which were later challenged subcutaneously with Meth A sarcoma or other noncross-reacting chemically induced sarcomas were found to be specifically immune to Meth A sarcoma. In addition, low levels of cytotoxic antibodies reactive to Meth A sarcoma were detected in the sera of 21 of 30 Meth A immune mice. Histological evaluation of the hemorrhagic tumor necrosis induced by rHuTNF-alpha suggests that the primary lesion is vascular, possibly directly on the endothelial cells. The mechanisms involved in the generation of specific cell-mediated antitumor immunity in this model are at present unknown.

Receptor binding and activation of polymorphonuclear neutrophils by tumor necrosis factor-alpha

The interaction of highly purified recombinant human tumor necrosis factor-alpha (rTNF-alpha) with human polymorphonuclear neutrophils (PMNs) was investigated. Binding of 125I-rTNF-alpha to PMN reached maximum levels in 30 min at 37 degrees C and in 2 h at 4 degrees C. Scatchard analysis of competitive binding data indicated approximately 6000 receptor sites per cell and a Kd of 1.37 nM. Binding data at 37 degrees C indicated a rapid internalization of rTNF-alpha. Following this receptor-mediated interaction, recombinant TNF-alpha was found to inhibit the migration of PMNs under agarose and to enhance PMN production of superoxide anion (O-2) in a dose-dependent manner. Furthermore, rTNF-alpha-activated PMNs caused a marked disruption of human umbilical-vein-derived endothelial cell monolayers and caused inhibition of their proliferative activities. These data substantiate the role of TNF-alpha as an activator of PMN functions and indicate that PMN/TNF-alpha/endothelial cell interactions may play a major role in inflammatory reactions.

Natural killer-sensitive targets stimulate production of TNF-alpha but not TNF-beta (lymphotoxin) by highly purified human peripheral blood large granular lymphocytes

Highly purified populations of large granular lymphocytes (LGL) have been shown to mediate natural killer (NK) cell activity. The mechanism of target cell killing by NK cells is as yet undefined; however, it has been postulated that such killing may involve soluble cytotoxic factors produced and secreted by NK cells. The data presented show that NK-sensitive, but not NK-resistant, tumor cell lines induce highly purified populations of human LGL to produce factors with cytotoxic and/or cytostatic activities. We have identified one of these factors as tumor necrosis factor-alpha (TNF-alpha), and have shown that production of this factor is enhanced by recombinant human interferon-gamma (rHuIFN-gamma). We have also examined the role of TNF-alpha in the cytotoxic function of NK cells. The data show that although highly purified LGL populations produce low levels of TNF-alpha, the cytotoxic/cytostatic activity of this lymphokine on tumor target cells does not correlate with the cytotoxic activity of highly purified populations of LGL on tumor target cells. Furthermore, NK cell-mediated cytotoxicity is not reliably inhibited by antibodies directed against various epitopes of recombinant human TNF-alpha and/or recombinant TNF-beta (lymphotoxin) or rHuIFN-gamma. These data show that although TNF-alpha is produced by highly purified NK-containing LGL cell populations, this factor does not appear to be responsible for NK cell cytotoxicity against classical NK target cells such as Molt-4 or K562. We suggest that NK function can be attributed to a combination of factors rather than to a single factor alone, and that at least two major phenomena are involved in LGL function: the rapid cytotoxic events which lead to the cell lysis measured in classical in vitro NK assays such as against K562; and the release of factors such as TNF-alpha with cytotoxic/cytostatic activities which would inhibit the growth of invading tumor cells in vivo.

Natural killer-sensitive targets stimulate production of TNF-alpha but not TNF-beta (lymphotoxin) by highly purified human peripheral blood large granular lymphocytes

Highly purified populations of large granular lymphocytes (LGL) have been shown to mediate natural killer (NK) cell activity. The mechanism of target cell killing by NK cells is as yet undefined; however, it has been postulated that such killing may involve soluble cytotoxic factors produced and secreted by NK cells. The data presented show that NK-sensitive, but not NK-resistant, tumor cell lines induce highly purified populations of human LGL to produce factors with cytotoxic and/or cytostatic activities. We have identified one of these factors as tumor necrosis factor-alpha (TNF-alpha), and have shown that production of this factor is enhanced by recombinant human interferon-gamma (rHuIFN-gamma). We have also examined the role of TNF-alpha in the cytotoxic function of NK cells. The data show that although highly purified LGL populations produce low levels of TNF-alpha, the cytotoxic/cytostatic activity of this lymphokine on tumor target cells does not correlate with the cytotoxic activity of highly purified populations of LGL on tumor target cells. Furthermore, NK cell-mediated cytotoxicity is not reliably inhibited by antibodies directed against various epitopes of recombinant human TNF-alpha and/or recombinant TNF-beta (lymphotoxin) or rHuIFN-gamma. These data show that although TNF-alpha is produced by highly purified NK-containing LGL cell populations, this factor does not appear to be responsible for NK cell cytotoxicity against classical NK target cells such as Molt-4 or K562. We suggest that NK function can be attributed to a combination of factors rather than to a single factor alone, and that at least two major phenomena are involved in LGL function: the rapid cytotoxic events which lead to the cell lysis measured in classical in vitro NK assays such as against K562; and the release of factors such as TNF-alpha with cytotoxic/cytostatic activities which would inhibit the growth of invading tumor cells in vivo.

Activation of human polymorphonuclear neutrophil functions by interferon-gamma and tumor necrosis factors

Recombinant human interferon-gamma (rHuIFN-gamma) and natural human tumor necrosis factor beta (nHuTNF-beta) (previously called lymphotoxin), purified to homogeneity, were used to assess their effects on certain functions of human polymorphonuclear neutrophils (PMN) in vitro. The treatment of PMN with 100 U of either rHuIFN-gamma or nHuTNF-beta for 20 min significantly increased their ability to phagocytize 1.5-microns latex beads as detected by flow cytometry. Preparations of recombinant human TNF-beta (rHuTNF-beta) showed activities similar to those of its natural counterpart in activating phagocytosis. In addition, a significant enhancement in PMN-mediated antibody-dependent cellular cytotoxicity was observed after treatment for 2 hr with IFN gamma and both TNF-alpha and TNF-beta. The enhancement by treatment with a combination of rHuIFN-gamma and nHuTNF-beta exceeded the enhancement caused by either agent alone. We also show that although lipopolysaccharide (LPS) is a potent stimulator of PMN function, polymyxin B can block LPS-induced but not lymphokine-induced activation. These data demonstrate new activities for both TNF-alpha and TNF-beta in augmenting the phagocytic and cytotoxic activities of PMN.

Activation of human polymorphonuclear neutrophil functions by interferon-gamma and tumor necrosis factors

Recombinant human interferon-gamma (rHuIFN-gamma) and natural human tumor necrosis factor beta (nHuTNF-beta) (previously called lymphotoxin), purified to homogeneity, were used to assess their effects on certain functions of human polymorphonuclear neutrophils (PMN) in vitro. The treatment of PMN with 100 U of either rHuIFN-gamma or nHuTNF-beta for 20 min significantly increased their ability to phagocytize 1.5-microns latex beads as detected by flow cytometry. Preparations of recombinant human TNF-beta (rHuTNF-beta) showed activities similar to those of its natural counterpart in activating phagocytosis. In addition, a significant enhancement in PMN-mediated antibody-dependent cellular cytotoxicity was observed after treatment for 2 hr with IFN gamma and both TNF-alpha and TNF-beta. The enhancement by treatment with a combination of rHuIFN-gamma and nHuTNF-beta exceeded the enhancement caused by either agent alone. We also show that although lipopolysaccharide (LPS) is a potent stimulator of PMN function, polymyxin B can block LPS-induced but not lymphokine-induced activation. These data demonstrate new activities for both TNF-alpha and TNF-beta in augmenting the phagocytic and cytotoxic activities of PMN.

In vivo antiviral activity of recombinant murine gamma interferon

Recombinant murine gamma interferon (gamma-IFN) was tested for its antiviral activity in vivo. IFN preparations purified to greater than 95% purity were administered to CD-1 mice infected with lethal doses of encephalomyocarditis (EMC) virus. An initial treatment with rMuIFN-gamma administered 4 h prior to infection with virus, followed by daily treatment for 3 consecutive days significantly protected mice against EMC virus as evidenced by animal survival after 3-4 weeks post-viral infection. Variations in the antiviral effect relative to dose levels and routes of administration were also studied.

In vivo augmentation of natural killer activity by combined treatment with recombinant gamma interferon and interleukin-2

The in vivo regulation of natural killer (NK) cell function by recombinant murine gamma interferon (rMuIFN-gamma) and recombinant human interleukin-2 (rHuIL-2) was investigated. Peritoneal exudate-derived natural killer (PE-NK) cells of mice treated with rMuIFN-gamma or rHuIL-2 exhibited significantly enhanced cytolytic activities against YAC-1 target cells. Compared with animals receiving treatment with either rMuIFN-gamma or rHuIL-2 alone, the sequential treatment of mice with both agents resulted in a significantly greater enhancement of PE-NK cell function, especially when rMuIFN-gamma was administered 24 h before treatment with rHuIL-2. The cytolytic activities were significantly diminished after pretreatment of effector cells with anti-Qa-5 antiserum and complement but not with anti-Lyt-3.2 antiserum. These data constitute the first evidence demonstrating the association between IFN-gamma and IL-2 in the regulation of NK cell function in vivo, reinforce the potential benefit of combined treatment with biological response modifiers, and show that the schedule of administration may be a critical requirement for optimal benefits of combined lymphokine treatment in vivo.

Augmentation of human natural cell-mediated cytotoxicity by recombinant human interleukin 2

Human peripheral blood mononuclear cells (PBMC) demonstrated increased natural cell-mediated cytotoxicity (NCMC) activity after only 5 min of exposure to purified recombinant human IL 2 or interferon (IFN)-gamma. The mechanism of NCMC augmentation by treatment with IL 2 is not entirely dependent on IFN-gamma production because: a) IL 2 was found to augment NCMC activity at levels which did not induce detectable IFN-gamma; b) IL 2 required only 5 min of exposure to PBMC to augment NCMC activity, whereas 3 hr of contact were required to demonstrate detectable IFN-gamma levels; c) the levels of NCMC enhancement by treatment with IL 2 exceeded the amount of NCMC enhancement that could be due to IFN alone; d) anti-recombinant IFN-gamma, which totally eliminated the augmentation of NCMC enhancement by IFN-gamma, only partially reduced the augmentation of NCMC activity by IL 2; and e) combination treatment of PBMC with IL 2 and IFN-gamma resulted in a synergistic enhancement of NCMC. The results strongly support the conclusion that augmentation of NCMC by IL 2 and IFN-gamma involve overlapping mechanisms.

Augmentation of human natural cell-mediated cytotoxicity by recombinant human interleukin 2

Human peripheral blood mononuclear cells (PBMC) demonstrated increased natural cell-mediated cytotoxicity (NCMC) activity after only 5 min of exposure to purified recombinant human IL 2 or interferon (IFN)-gamma. The mechanism of NCMC augmentation by treatment with IL 2 is not entirely dependent on IFN-gamma production because: a) IL 2 was found to augment NCMC activity at levels which did not induce detectable IFN-gamma; b) IL 2 required only 5 min of exposure to PBMC to augment NCMC activity, whereas 3 hr of contact were required to demonstrate detectable IFN-gamma levels; c) the levels of NCMC enhancement by treatment with IL 2 exceeded the amount of NCMC enhancement that could be due to IFN alone; d) anti-recombinant IFN-gamma, which totally eliminated the augmentation of NCMC enhancement by IFN-gamma, only partially reduced the augmentation of NCMC activity by IL 2; and e) combination treatment of PBMC with IL 2 and IFN-gamma resulted in a synergistic enhancement of NCMC. The results strongly support the conclusion that augmentation of NCMC by IL 2 and IFN-gamma involve overlapping mechanisms.

Effects of bacteria-produced human alpha, beta, and gamma interferons on in vitro immune functions

The effects of bacteria-produced human interferons (HuIFN) alpha, beta, and gamma on in vitro immune functions of human peripheral blood mononuclear cells (PBMC) were studied. Proliferative response to phytohemagglutinin was significantly inhibited by the addition of HuIFN-alpha 2 or HuIFN-beta at 10, 100, or 1000 U/ml. In contrast, HuIFN-gamma showed suppressive activities only when added at 1000 U/ml. HuIFN-alpha 2 or HuIFN-beta caused significant inhibition of human mixed-lymphocyte reaction (MLR) as measured by [3H]thymidine incorporation. Similar inhibition was caused by HuIFN-gamma when it was added only at very low concentrations (1 U/ml); 10, 100, or 1000 U/ml resulted in no or only a modest increase in MLR. All three interferons exhibited dose-related effects on PWM-induced immunoglobulin synthesis in cultures of PBMC. These data demonstrate that purified interferons produced by recombinant DNA technology can significantly alter in vitro immune functions and that HuIFN-gamma has properties which are different from those of HuIFN-alpha 2 or HuIFN-beta.

Bacteria-derived human leukocyte interferons alter in vitro humoral and cellular immune responses

Cultures of gradient-purified human peripheral blood mononuclear cells (PBMC) have been employed to examine the effects of three bacteria-derived human leukocyte interferon subtypes on certain aspects of in vitro immune responses. The addition of highly purified IFN-alpha 1, -alpha 2, -alpha 2/alpha 1 to PMBC cultures stimulated with phytohemagglutinin (PHA) or pokeweed mitogen resulted in a significant suppression of the mitogenic response. This suppression required the presence of interferon in the cultures because pretreatment of cells and removal of interferon had no effect on their response to PHA. The presence of these interferons at 200 U/ml also caused a substantial reduction of human mixed-lymphocyte reactions (MLR) as measured by [3H]thymidine incorporation by responder cells. Interestingly, pretreatment of stimulator cells was sufficient for this reduction to occur whereas pretreatment of responder cells had no effect on their ability to respond to allogenic stimulation. In contrast to these suppressive effects, the three interferons enhanced human in vitro primary immune response to sheep red blood cells (SRBC). These data demonstrate that both purified interferon subtypes and genetic hybrids of human interferons produced by recombinant DNA technology have effects on in vitro immune responses.

The mechanism of appearance of specific antibody-forming cells in lungs of inbred mice after intratracheal immunization with sheep erythrocytes

Immunization, ablation, and adoptive transfer studies were performed in inbred mice to define in vivo the cellular mechanisms for the appearance of specific antibody-forming cells (AFC) in pulmonary parenchyma. Mice were immunized locally or systemically with sheep erythrocytes (SRBC), and the concentrations of IgM- and IgG-producing AFC were measured in lung and extrapulmonary lymphoid tissues with a hemolytic-plaque assay. Splenectomized mice and recipients of adoptively transferred, sensitized lymphocytes were examined. We found that primary intratracheal (IT) immunization regularly failed to induce the appearance of AFC in lungs, whereas IT boosting of primed animals consistently succeeded. Immunization experiments showed that mice could be primed by any of a variety of local or systemic routes, but that the IT route of boosting was an absolute requirement for the induction of pulmonary AFC in primed mice. Recruitment of AFC into lungs by IT boosting of systemically primed and boosted animals was antigen-specific. Splenectomy performed prior to priming reduced, but did not ablate, the pulmonary AFC-response to IT boosting. Adoptive transfer of sensitized lymphocytes to naive recipient mice substituted for antigen-priming, which is required for induction of pulmonary AFC by IT challenge. Results of adoptive transfer studies demonstrate that IT challenge with specific antigen recruits systemically administered sensitized lymphocytes into the lung. We conclude that local primary immunization of mice results in the generation of AFC in extrapulmonary lymphoid tissues and that the major mechanism for the appearance of AFC in lungs is through recruitment of sensitized cells from systemic sources by intrapulmonary boosting with specific antigen.

An indirect assay for canine leukocyte migration inhibitory factor (LIF): demonstration of its species specificity

An indirect assay in agarose-gel was developed to measure secretion of leukocyte migration inhibitory factor (LIF) by canine lymphocytes. Supernatants from cultures of mitogen- or alloantigen-stimulated canine peripheral blood lymphocytes were assayed for LIF activity using purified granulocytes as indicator cells. Canine LIF activity could be detected provided either autologous or allogeneic canine granulocytes were used as indicator cells. In contrast, canine LIF uniformly failed to inhibit the migration of human granulocytes. Likewise, human LIF inhibited the migration of human but not canine granulocytes in this assay. The data indicated that this species specificity could be due to differences in the structures of LIF receptors on canine and human granulocytes.

Canine surface active material and pulmonary lymphocyte function. Studies with mixed-lymphocyte culture

Canine bronchoalveolar cells, obtained by lavage, were enriched for lymphocytes by adsorption to plastic or by filtration over nylon wool and tested for their ability to function in the mixed lymphocyte culture (MLC) reaction. Pulmonary lymphocytes were markedly hyporesponsive to stimulation with allogeneic cells in vitro: their responses rarely exceeded 10% of those of blood lymphocytes obtained simultaneously from the same donor. However, pulmonary lymphocytes did function as stimulating cells, inducing allogeneic blood lymphocytes to proliferate in MLC. The failure of pulmonary lymphocytes to respond in MLC, coupled with their ability to stimulate clearly, distinguishes these cells from circulating blood lymphocytes. The effect of canine surface active material (SAM), a lipoprotein unique to the lung, on the function of blood lymphocytes in MLC was studied. A transient exposure to SAM in vitro profoundly suppressed blood lymphocyte responses to allogenic stimulation, but had only a minor effect on their function as stimulator cells in MLC. Thus, exposure to SAM in vitro converts normal blood lymphocytes into cells whose function mimics that of pulmonary lymphocytes. These results suggest that exposure of pulmonary lymphocytes to SAM in vivo may contribute to their abnormal immune reactivity in vitro.

Isolation of feline syncytia-forming virus from oropharyngeal swab samples and buffy coat cells

Thirteen of 40 female cats were found to be chronically infected with feline syncytia-forming virus (FeSFV). Attempts to isolate the virus from these cats by conventional methods were not successful. However, virus was isolated from oropharyngeal swab samples and buffy coat cells. A new method was used involving inoculation of actively dividing Crandell feline kidney cell cultures. Cultures were trypsinized 3 days after inoculation and, as a result, cytopathic effect was amplified and ability to detect the virus was enhanced. The FeSFV was detected in 93% (92/88) of the oropharyngeal swab samples and 100% (14/14) of the buffy coat cell specimens. Feline sera were tested by immunodiffusion for precipitating antibody against FeSFV antigen. There was 100% correlation between viral infection and the presence of precipitating antibody. Virus and antibody persisted in infected cats for the duration of this study (8 months for 5 of the infected cats). Urolithiasis was observed in 15 of 28 male cats. Although a direct relationship between FeSFV infection and urolithiasis was not established, most of these male cats (20 of 21) had antibody to FeSFV.

Tumor antigen and human chorionic gonadotropin in CaSki cells: a new epidermoid cervical cancer cell line

Epidermoid cervical carcinoma cells (CaSki line) have been established in continuous culture. When leukocytes from cervical cancer patients were incubated with CaSki culture fluid concentrates, inhibition of leukocyte migration was observed in more than 70 percent of the patients tested. By contrast, significantly less inhibition was observed with normal donor leukocytes or leukocytes from patients with other types of cancer. These results were consistent with the expression of tumor-associated antigen by CaSki cells. Analysis of the serum from the donor of the cell line at the time of tumor biopsy, and of CaSki culture fluids, demonstrated the presence of the beta subunit of human chorionic gonadotropin.

Effect of Crude and Purified hCG on Lymphocyte Blastogenesis

Crude APL hCG completely inhibited blastogenesis induced by phytohemagglutinin, pokeweed mitogen, or concanavalin A in normal lymphocytes and lymphocytes obtained from cancer patients. Phenol in quantities comparable to its concentration in commercial lyophilized APL hCG also completely inhibited all three mitogenic responses. By contrast, similar doses of highly purified hCG had no inhibitory effect; higher concentrations produced only slight inhibition. Beta-hCG had a partial (less than 50%) inhibitory effect that was dose-independent and nonreproducible.

Graft-vs.-host reaction in tissue culture

The primary purpose of this study has been to validate the in vitro graft-vs.-host reaction as an experimental system. Time-dose studies have been presented for cells obtained from spleen, thymus, cortisone-treated thymus, inguinal lymph node, mesenteric lymph node, thoracic duct, and bone marrow cells. Both the degree of splenomegaly and the onset of spleen enlargement were found to be dependent on the number and source of cells tested. The effect of several immunosuppressive agents was examined. Amantadine was found to suppress completely the graft-vs.-host reaction in vitro when present at a concentration of 75 microg/ml. Pretreatment of effector cells with mitomycin C prevented their subsequent ability to cause a graft-vs.-host reaction. The effect of X irradiation on immunocompetence of spleen cells in vitro paralleled the known effect of irradiation on in vivo immunocompetence. Preimmunization did not increase the number or effectiveness of immunocompetent cells when measured under standard in vitro conditions. Preimmunization did, however, permit persistence of immunocompetence after immunosuppressive doses of X irradiation. Studies using congenic lines, moreover, indicated that the preimmunization effect could be demonstrated in strain combinations differing only in factors determined by the H-2 complex of genes. A weak graft-vs.-host reaction could be detected in strain combinations not involving differences at the H-2 locus. The potential of the in vitro graft-vs.-host reaction as a highly reproducible, quantifiable, internally controlled, and experimentally accessible system for study of such critical problems as cell differentiation and cell interactions is discussed.