Effect of various interferons on the spontaneous cytotoxicity exerted by lymphocytes from normal and tumor-bearing patients.

Natural killer cell activity, which represents the spontaneous cytotoxicity of lymphocytes toward tumor cells, has been measured in 173 tumor-bearing patients and 25 healthy volunteers; no significant difference was found in mean natural killer cell activity between the two groups. The parameters of interferon-induced activation of natural killer cells were studied in order to provide a suitable test for monitoring the effect of interferon in clinical trials. The three interferons tested (leukocyte, lymphoblastoid, and fibroblast) were equally active in inducing spontaneous cytotoxicity of lymphocytes from all healthy individuals and tumor-bearing patients studied. Incubation for one hr with 100 units of interferon was sufficient to increase spontaneous cytotoxicity activity, the maximum effect being obtained when lymphocytes were incubated with 1000 units of any of the interferons used. This effect was blocked with the appropriate antiinterferon sera. The target cells for interferon seem to be positive Fc gamma receptor lymphocytes.

Proliferative response of hairy cells to B cell growth factor (BCGF): in vivo inhibition by interferon-alpha and in vitro effects of interferon-alpha, -beta, and -gamma.

Hairy cell leukemia (HCL) is a pre-plasma B cell tumor which responds to interferon (IFN)-alpha therapy. In vitro, B cell growth factor (BCGF) can induce proliferation of hairy cells. We have investigated the effect of in vitro and in vivo treatments with different recombinant IFN on the capacity of hairy cells to proliferate in response to human BCGF. In vitro treatment of leukemic cells from HCL patients with recombinant IFN-alpha-2 (5/5 cases) or IFN-beta (4/5 cases) resulted in a marked inhibition of the BCGF-dependent response. This suppressive effect was obtained with IFN concentrations of 1000, 100 IU/ml, and even occasionally 10 IU/ml. In contrast, no such inhibition was observed with IFN-gamma, despite the presence of specific IFN-gamma receptors on hairy cells at densities similar to receptors for IFN-alpha/beta. The IFN-alpha-induced suppression of the proliferative response of hairy cells to BCGF was also observed in vivo in two patients within 6-12 hr after administration of single doses of IFN-alpha. When hairy cells were maintained in culture for 1 week, they recovered their capacity to be stimulated by BCGF. This reversion was also shown in vivo in hairy cells isolated 1 week after IFN administration. Since in vivo growth of hairy cells could possibly result from the autocrine secretion of BCGF, we propose that the therapeutic effect of IFN-alpha on HCL may be due in part to an inhibition of such autocrine loop.

Expression of the B8.7 antigen on hairy cells and relation with the LMW-BCGF response.

Hairy cells are classified as B cell tumors at a preplasma cell stage of differentiation and are believed to represent cells undergoing a switch process. These cells are stimulated in vitro to DNA synthesis and multiplication in the presence of the lymphokine LMW-BCGF. We have tested the level of expression on these cells of the newly described B8.7 activation marker which has been reported to be associated with the capacity of various B cells to respond to LMW-BCGF. The presence of this marker has been readily detected on the hairy cells of 10 of the 12 patients tested in this study; interestingly, for one of the negative cases, the tumor cells were unable to proliferate in response to LMW-BCGF. As on normal B cells, a marked inhibition of the LMW-BCGF dependent response could be achieved in the presence of a monoclonal anti-B8.7 antibody, sustaining the proposal that the B8.7 molecule is involved in the signaling pathway of this growth factor. IFN-alpha is highly efficient in the therapy of hairy cell leukemia (HCL), and we confirm in the present study that IFN-alpha also inhibits the LMW-BCGF dependent proliferation of hairy cells in vitro. In addition, we show that this inhibition is independent of a significant modulation of the B8.7 antigen, a molecule putatively associated with the LMW-BCGF receptor.

The use of a complementary DNA probe to detect accumulation of mengo RNA in infected cells pretreated with interferon.

Complementary DNA (cDNA) from Mengo virus RNA has been synthesized and used as a probe to measure the synthesis and accumulation of viral RNA in Mengo infected L cell cultures, treated or untreated with interferon. Under experimental conditions used (200 units interferon/ml and 50 virus plaque-forming units/cell) results show that there is some synthesis of Mengo virus RNA in cells treated with interferon. One hour after infection, treated cells contain three times less viral RNA than untreated cells; five hours after infection, this difference has increased to ten fold. As in the control, no fragmented Mengo virus RNA molecules were found in interferon treated cells. The smaller recovery of infectious particles from interferon treated cells as compared to RNA accumulation suggests that not only RNA accumulation is inhibited but also a step posterior in viral maturation.

Scintigraphic study of radiolabelled interferon-alpha in osteosarcoma patients.

Interferon-alpha is currently under evaluation as an antineoplastic agent in several types of tumour. Despite its clear in vitro effects, the effectiveness of interferon in vivo is limited. To assess whether this discrepancy reflects pharmacokinetic limitations, the authors analysed interferon distribution in 2 osteosarcoma patients by scintigraphy using 123I-interferon-alpha-2a. Numerical analysis of the scintigraphic records demonstrated that the main organs of elimination were the kidneys, when the calculation was made on the basis of surface area. On the other hand, the apparent total uptake by liver (whose projection surface--i.e. the area exposed to the lens--is greater) was higher, reaching about 25 to 30% of the injected dose. The projection surface of the tumour was able to take up radiolabelled interferon in both cases, resulting in a 4-fold increase in the external radiation count compared with the equivalent region of the contralateral limb (although it is not possible to determine whether the label is present on the tumour itself or on the surrounding inflammatory cells). Thus, interferon-alpha seems able to reach at least the immediate neighbourhood of osteosarcoma mass.

Action of interferon-alpha on hairy cell leukemia: expression of specific receptors and (2'-5')oligo (A) synthetase in tumor cells from sensitive and resistant patients.

IFN-alpha induces tumor regression with a high percentage of complete remissions in hairy cell leukemia. We have recently reported that hairy cells express specific IFN-alpha receptors which are down-regulated upon therapy. We show here that the activity of 2-5 A synthetase, an IFN-induced enzyme, is 2 to 7-fold stimulated in hairy cells from responsive patients within 12-24 h after the first IFN dose. This in-vivo enzyme induction paralleled the kinetics of receptor down-regulation. In one patient who was unresponsive to IFN-alpha treatment neither expression of IFN-alpha receptor nor change in 2-5 A synthetase were expressed and modulated as in sensitive patients. In-vitro treatment of hairy cells with recombinant interferons showed that IFN-beta 1 was able to induce this enzyme to the same extent than IFN-alpha 2, whereas IFN-gamma was inactive despite the presence of specific IFN-gamma receptors. Our results indicate that IFN-alpha can exert its therapeutic effects by acting directly on the hairy cells through interaction with surface membrane receptors. Induction of 2-5 A synthetase can be one of the steps involved in this action. However, both mechanisms, as well as receptor down-regulation are not sufficient to explain the responsiveness of hairy cell leukemia to IFN-alpha.

Correlation between the biological and therapeutic effects of interferon-alpha in low-grade nodular non-Hodgkin's lymphoma: lack of in vivo down-regulation and reduced affinity of IFN-alpha receptors in unresponsive patients.

We investigated the correlations between the biological effects of interferon-alpha (IFN-alpha) and clinical responsiveness in low-grade non-Hodgkin's lymphomas (NHL). In this disease, 40-50% of cases respond to IFN-alpha therapy. Patients with nodular NHL were selected for a phase II trial in which they were treated daily with 9 x 10(6) U of IFN-alpha 2a. Binding experiments with [125I]IFN-alpha 2a showed the presence of IFN-alpha receptors on tumor B-cells isolated from lymph nodes before therapy in 9 out of 10 patients. Receptor levels were not related to the subsequent clinical responses. However, no specific binding was detected in one patient who turned out to be unresponsive to IFN-alpha treatment. Single injections of IFN-alpha 2a before beginning the therapeutic protocol resulted in down-regulation of IFN-alpha receptors without change in their affinity in peripheral blood leukocytes from only patients who subsequently responded to therapy (4/10). In 4/5 non-responders and one patient displaying a minor response, receptor numbers did not decrease but Kd values rose markedly in all six cases. These results indicate that lack of in vivo IFN-alpha receptor down-regulation and reduced receptor affinity, as detected before therapy, may be correlated with failure of IFN-alpha therapy in nodular NHL.

Synergistic activities of type I (alpha, beta) and type II (gamma) murine interferons.

Type I (alpha, beta) and type II (gamma) murine interferons are able to potentiate each other with respect to the inhibition of encephalomyocarditis (EMC) virus and of herpes simplex virus type 1 (HSV-1) multiplication in a murine cell line (DBT). Examination of two double-stranded RNA-dependent enzymes in DBT cells, the 2-5A synthetase and the 67,000 MW protein phosphokinase indicates that mixed interferon preparations act synergistically at least with respect to an increase in the activity of the former enzyme. The results obtained with gamma interferons of different origin and of different specific activity suggest that interferon itself, rather than the lymphokines present in the interferon preparations, is responsible for the synergistic effect.

Protection of young rats from acute Trypanosoma cruzi infection by interferon-gamma given to their mothers during pregnancy.

We investigated whether administration of interferon-gamma (IFN-gamma) to pregnant rats, infected or not with Trypanosoma cruzi, was likely to protect their offspring from trypanosomal infection. Upon mating with syngeneic sires, four groups of 70-day-old female 1 rats were subjected to one of the following procedures: treatment with recombinant rat (Rr)IFN-gamma 50,000 IU/rat five times/week for three weeks; infection with 1 x 10(6) trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-gamma treatment as given to the former group; the same protocol but IFN-gamma injections being replaced by injection with physiologic saline. Offspring were nursed by their mothers until weaning and then infected with a similar dose of T. cruzi. Pregnant rats showed no exacerbated infection but a self-resolving mild disease, regardless of whether or not they had received IFN-gamma. Maternal infection with T. cruzi and/or IFN-gamma treatment did not affect gestational outcome. Offspring born to both groups of IFN-gamma-treated mothers were almost fully protected from acute infection, and showed higher levels of anti-T. cruzi IgG antibodies when compared with young born to their respective IFN-gamma-untreated mothers. Measurements of IFN-gamma serum activities indicated that ameliorated acute disease in offspring whose mothers were given IFN-gamma during gestation, was not associated with increased levels of endogenously produced IFN-gamma.

Clinical healing of antimony-resistant cutaneous or mucocutaneous leishmaniasis following the combined administration of interferon-gamma and pentavalent antimonial compounds.

In an open trial, longer courses of pentavalent antimonials (Sbv) at sub-optimal doses (10 mg/kg body weight), in association with recombinant human interferon-gamma (IFN-gamma) (100 micrograms/m2 of body surface area) were administered, by daily intramuscular injections, to 13 patients with diagnoses of cutaneous or mucocutaneous leishmaniasis unresponsive to Sbv. Four patients presented with large skin ulcers, and 9 had mucosal involvement as the main manifestation, the latter affecting the nose (3 cases), nose and septum (2 cases), nose and oral cavity (1 case), and nose, pharynx and larynx (3 cases). Except for one case with severe involvement of the upper respiratory tract, the lesions were fully resolved by the end of therapy (mean duration 40 +/- 12 [SD] d, range 30-60 d) in the 11 patients who completed therapy. The main side effects were headache and fever (7 cases), together with leucopenia and eosinophilia (4 cases). It is concluded that combined administration of low doses of Sbv plus IFN-gamma may provide a novel therapeutic approach for the treatment of antimony-resistant cutaneous or mucocutaneous leishmaniasis. The possible mechanisms by which IFN-gamma contributes to resolution of the disease are discussed.

In vivo protective effect of the lectin from Canavalia brasiliensis on BALB/c mice infected by Leishmania amazonensis.

In vivo administration of Canavalia brasiliensis lectin (at the time of infection, or maintained throughout the infection) reduced the lesions of highly susceptible BALB/c mice infected by Leishmania amazonensis. At the doses used C. brasiliensis lectin (ConBr) does not interfere with penetration or fate of Leishmania in the macrophages in vitro. Since Interferon-gamma (IFN-gamma) is the major macrophage activating factor, and considered a critical element in the successful immune response against leishmaniasis, we explored its participation in this phenomenon. ConBr either in vivo or in vitro induced IFN-gamma production in normal or in leishmania-infected BALB/c mice. However we were unable to change the course of disease by in vivo IFN-gamma administration (although IFN-gamma preparations were effective in inducing a leishmanicidal effect in vitro on L. amazonensis-infected peritoneal macrophages). Additionally, IFN-gamma neutralization with anti-IFN-gamma monoclonal antibody did not alter the protection conferred by ConBr administration. These data show that lectin administration in vivo is protective in the otherwise unchecked L. amazonensis infection of BALB/c mice, and suggest that such effect is not mediated by IFN-gamma.

Interferon induction by Lactobacillus bulgaricus and Streptococcus thermophilus in mice.

This study investigates the effect of intraperitoneal injection of L. bulgaricus and S. thermophilus on interferon production by Swiss mice. The serum from mice given 5 x 10(7) L. bulgaricus in 0.5 ml saline showed a maximal production of 300 U/ml of alpha/beta interferon activity six hours after injection. Cellular integrity appears to be necessary for stimulation; heat-treated bacteria had little effect, while irradiated-bacteria had a greater effect. TNF was also produced, the sera of mice with high IFN also contained 300 U/ml TNF. Streptococcus thermophilus produced no detectable increase in serum IFN, but the 2'-5' A synthetase activity of peritoneal cells was elevated suggesting that small amounts of interferon were produced. Injection of Streptococcus thermophilus plus Lactobacillus bulgaricus did not change the serum interferon response to L. bulgaricus. These observations suggest that non-pathogenic bacteria such as those used in food processing, can stimulate IFN production in mice. There is some evidence that the bacterial cell walls might be responsible for at least part of this effect.

In vivo and in vitro induction of (2'-5') oligoadenylate synthetase by human interferons in leukocytes from healthy donors and patients with renal cancer and hairy cell leukemia.

The effect of in vivo administered interferon-alpha (IFN-alpha) on 2-5-oligoadenylate (A) synthetase activity of peripheral blood mononuclear cells (PBMC) was compared in patients with hairy cell leukemia and renal cell cancer. Basic levels of this enzyme varied from donor to donor, but mean levels were not significantly different in patients with renal cell cancer or hairy cell leukemia compared to healthy donors. After a single injection of 3 x 10(6) IU IFN, these basic levels rose 2- to 8-fold within 12-24 h post-injection and reverted to pretreatment levels after 48 h. The extent of this in vivo stimulation by IFN-alpha was similar in patients with hairy cell leukemia and renal cell carcinoma, and was correlated with down-regulation of IFN-alpha receptors. The in vitro effects of IFN-alpha, -beta and -gamma were compared after 18 h treatment with 10, 10(2) and 10(3) IU/ml of each IFN. Unlike IFN-alpha and -beta, IFN-gamma did not induce 2-5 A synthetase activity in either normal PBMC or hairy cells; these results were related to the effects of the three IFN on proliferative response of normal PBMC to phytohemagglutinin. Our data support the idea that 2-5 A synthetase activity is a marker of biological response to interferon treatment in human cancers.

Serum interferon activity of patients with leishmaniasis.

Serum from a significant proportion of 29 cutaneous and 12 mucocutaneous leishmaniasis patients exhibited interferon activity in a cytopathic assay: positive tests were obtained for 24.1% and 41.7% of the patients, respectively. Similar positive frequencies were observed in other parasitic diseases (schistosomiasis, 12.5%; toxoplasmosis, 20%; Chagas' disease, 16%; leprosy, 12.5%; tuberculosis, 30%). In contrast, none of the 44 serum samples from American visceral leishmaniasis (AVL) patients had interferon activity during the active stage of the disease. However, 13% of the samples obtained from patients recovered from AVL were positive.

[Phase-1 study of the tolerance for increasing doses of recombinant human alpha 2 interferon in patients with advanced cancer]. / Essai phase l' de tolérance à des doses croissantes d'interféron recombinant human alpha 2 chez des patients porteurs de cancers avancés.

Thirteen patients with malignant tumors were entered into a phase I trial with recombinant DNA human alpha 2 interferon (IFN alpha 2). The patients were given I.M. escalating doses of IFN alpha 2 ranging from 1-10(6) to 200-10(6) IU with a 72 hours washout between injections. In the majority of the patients, subjective symptoms were noted: fever, headache, chills, nausea, myalgias. Asthenia, anorexia, drowsiness appeared after the highest doses and disappeared without any sequellae. Leucopenia and thrombopenia were seen in 11 out of 13 patients. Hepatocellular toxicity was observed in 9 cases. Cardiac and vascular functions were not impaired by IFN alpha 2. The pharmacokinetic studies showed a maximum serum concentration between 4 and 6 hours after injection and the peak value was directly proportional to the dose. No neutralizing INF alpha 2 serum factor was detected during the treatment. The peak value for serum beta 2 microglobulin occurred 48 hours after and the N.K. activity was variably modified by IFN alpha 2 injections. A major clinical response was observed in 1 case, a minor response in 3 cases and a stabilisation of the disease in 4 cases.

The value of a radioimmunological monitoring in cancer patients treated with interferon alpha.

Using a radioimmunoassay for human leukocyte interferon (IFN alpha), pharmacokinetic studies were carried out in twelve cancer patients given sequential intramuscular injections of Hu IFN alpha 2. Even though individual monitoring of serum IFN titers emphasized, for a given dose, marked quantitative variations of the observed maximum concentrations, their mean values were found to be dose-dependent (358 +/- 167 U/ml at 30.10(6) U and 1044 +/- 599 U/ml at 100.10(6) U doses). Comparison with bioassay results showed that IFN activities measured in sera were of the same order of magnitude as those calculated from radioimmunoassay standard curves. Data obtained from this series on observed peak time, half-life value and serum concentrations were consistent with those reported by the other groups using recombinant leukocyte interferon in clinical trial. Therefore, radioimmunoassay is an useful method for routinely assaying IFN alpha used either as antitumour or antivirus agent because of its high sensitivity (4 U/ml) and its simplicity.

[Interferon gamma as an immunological strategy for the treatment of human leishmaniasis]. / El interferon gamma com estrategia immunológica para el tratamiento de la leishmaniasis humana.

T lymphocytes from patients with visceral leishmaniasis treated in vitro with leishmania antigens are unable to proliferate and to produce gamma interferon. These patients have negative specific skin tests. Opposite results are obtained in patients with another clinical form of the disease named mucocutaneous leishmaniasis, in which both tests are positive. Nevertheless, patients with visceral leishmaniasis or mucocutaneous leishmaniasis, refractory to chemotherapy (antimonium complex), were cured when treated with antimonium in combination with gamma interferon, in spite of different immunological profiles. Different interpretative hypotheses of the reversion of chemoresistance induced by gamma interferon are discussed.