Resistance to interferon-alpha in a mouse B-cell lymphoma involves DNA methylation.

Resistance to interferon-alpha (IFN-alpha) in the 38C13 B-lymphoma cell line results in the loss of antiviral, antiproliferative, and immune regulatory functions of IFN-alpha. Mutagenesis with ethylmethylsulfonic acid (EMS), which can induce point mutations in DNA, increases the frequency of resistance to IFN-alpha 20 to 40-fold. In contrast, treatment with 5-azacytidine, which causes hypomethylation of DNA, reduces the frequency of resistance to 5-10% of control.

Intermittent, alternating, and concurrent regimens of zidovudine and 2'-3' dideoxycytidine in the LP-BM5 murine induced immunodeficiency model.

The murine retrovirus-induced immunodeficiency model, LP-BM5, was used to evaluate the efficacy of intermittent and alternating regimens of zidovudine (azido-2'-3'dideoxythymidine; AZT) and 2'-3' dideoxycytidine (ddC) compared with continuous and concurrent therapy. Intermittent oral AZT therapy was less effective in protecting mice inoculated with LP-BM5 virus than was continuous oral AZT therapy. Continuous oral ddC therapy (80 mg/kg/day) increased survival time an average of 3.

Zidovudine (AZT) reduces virus titer, retards immune dysfunction, and prolongs survival in the LP-BM5 murine induced immunodeficiency model.

Using the murine LP-BM5 retrovirus-induced immunodeficiency model, the therapeutic value of zidovudine (AZT) was analyzed. Continuous low dose (60 mg/kg per day) oral AZT administration for 6 weeks increased survival time by 5-6 weeks. Decreasing the duration of therapy to 3 weeks decreased the mean survival time.

Changes in the expression of idiotype antigen on murine B-cell lymphoma after hyperthermia alone and in combination with interferon and tumour necrosis factor.

The effect of interferon (IFN) and tumour necrosis factor (TNF), either alone or combined with hyperthermia, on cell proliferation and expression of idiotype antigen on a murine B-cell lymphoma has been studied. Incubation with same doses of IFN-alpha and IFN-gamma reduced cell proliferation to the same extent. Hyperthermia potentiated the antiproliferative activity of IFN-alpha and IFN-gamma.

Zidovudine (azido dideoxythymidine) inhibits characteristic early alterations of lymphoid cell populations in retrovirus-induced murine AIDS.

Using flow cytometry technology and multiparameter analyses, we report early and characteristic alterations in lymphoid cell profile in spleen and lymph nodes due to LP-BM5 retrovirus disease (murine AIDS (MAIDS)) and the effect of azido dideoxythymidine, a nucleoside inhibitor, on these changes. MAIDS has been characterized by rapid and profound lymphoproliferation accompanied by hypergammaglobulinemia and immunosuppression. As early as 2 wk postinfection, there is a selective depletion of CD8+ cells whereas the total number of CD4+ cells increases throughout the first 8 wk of infection although the frequency is relatively stable.

Enhanced in vivo therapeutic response to interferon in mice with an in vitro interferon-resistant B-cell lymphoma.

A stable subline of 38C13 B-cell lymphoma (SIR-1) resistant to the antiproliferative effects of alpha-interferon (IFN) was isolated. In addition to defects in antiproliferative effects of IFN, SIR-1 is defective in IFN-mediated antiviral activity against both encephalomyocarditis virus and vesicularstomatitis virus. It is also defective in the induction of 2'-5'-oligoadenylate synthetase mRNA and enzyme activity, enhancement of H-2 antigen expression, and transient induction and subsequent repression of c-myc by IFN.

Treatment of B-cell lymphomas with anti-idiotype antibodies alone and in combination with alpha interferon.

Idiotypes are distinct clonal markers for B-cell lymphomas. Previously we reported the use of anti-idiotype antibodies in the therapy of patients with B-cell malignancies. Because synergy was demonstrated with the addition of alpha interferon to anti-idiotype antibodies in a murine lymphoma model, we performed a clinical trial combining these two agents.

Synergistic antitumor activity with IFN and monoclonal anti-idiotype for murine B cell lymphoma. Mechanism of action.

Combination therapy with syngeneic anti-idiotype antibody and human hybrid rIFN-alpha A/D synergistically increase survival in C3H/HeN mice challenged with a lethal dose of tumor cells. C3H/HeJ mice, which have previously been described to be LPS hyporesponsive and have a defect in Fc gamma R function, did not respond to anti-idiotype therapy as well as C3H/HeN normal mice. This defect was completely corrected in animals treated simultaneously with IFN.

Comparison of combinations of interferons with tumor specific and nonspecific monoclonal antibodies as therapy for murine B- and T-cell lymphomas.

Two murine models, C3H 38C13 B-cell lymphoma and AKR SL2 T-cell lymphoma were used to determine the efficacy of three different interferon preparations, recombinant human hybrid interferon-alpha A/D, recombinant murine interferon (rMIFN)-gamma, and natural MIFN-alpha/beta (greater than or equal to 85% beta), alone and in combination with tumor specific and nonspecific monoclonal antibody therapy. All three interferon preparations have direct in vitro antigrowth activity for 38C13 and SL2. All three interferons have direct antitumor activity in vivo for 38C13 lymphoma at high doses; however, none of these interferons has independent antitumor activity for SL2 in vivo.

Beta interferon produced by keratinocytes in human cutaneous infection with herpes simplex virus.

beta Interferon (IFN) was demonstrated by specific, sequential antibody-neutralization assays of vesicle fluids from patients with recurrent skin lesions due to herpes simplex virus. To determine the origin of this antiviral activity, we cultured keratinocytes from normal facial skin and infected them with three strains of herpes simplex virus. Keratinocyte cultures then developed characteristic cytopathic changes, and antiviral activity was found in culture supernatant media.

Regulation of guinea-pig immune functions by interleukin 2: critical role of natural killer activity in acute HSV-2 genital infection.

We have previously demonstrated that recombinant interleukin 2 (rIL 2) has a protective effect against acute HSV-2 infection in guinea pigs with a biphasic dose response which peaked between 4 and 20 X 10(4) U/kg, whereas 8 X 10(5) U/kg showed no effect on disease. Animals that escaped infection appeared lack immunologic memory to HSV-2, suggesting a nonspecific immune mechanism. In this study we have found that NK activity of fresh splenocytes measured against HSV-2 infected human foreskin fibroblast (HFF) is stimulated in vitro and in vivo by rIL 2 in a biphasic dose range similar to that determined for protection against disease.

Synergistic antitumor effect of interferon and anti-idiotype monoclonal antibody in murine lymphoma.

Both IFN-alpha and anti-idiotype monoclonal antibody therapy have significant antitumor activity in vivo in a murine B cell lymphoma model. Combination therapy with syngeneic anti-idiotype antibody of the IgG2a or IgG2b isotype (a single i.p.

Human keratinocyte-lymphocyte reactions in vitro.

To extend our observation that recombinant gamma interferon (r-IFN-gamma) induces the synthesis and expression of HLA-DR antigen we have investigated 2 major areas including the modulation of r-IFN-gamma-induced HLA-DR expression and the possible immunologic consequences of keratinocyte HLA-DR expression in vitro. The induction of keratinocyte HLA-DR expression was greater for continuous compared with pulse dosage (0.5-24 h) of r-IFN-gamma and was markedly decreased after trypsinization of attached monolayers into single cell suspensions.

Immunomodulatory and antiproliferative effect of recombinant alpha, beta, and gamma interferons on cultured human malignant squamous cell lines, SCL-1 and SW-1271.

Two different human malignant squamous cell lines (SCL-1 and SW-1271) and normal human foreskin fibroblasts were treated with recombinant human alpha, beta, and gamma interferons. HLA-DR expression was induced in a concentration-dependent fashion only on the SCL-1 cells treated with recombinant human gamma interferon (r-IFN-gamma) (10(2)-10(3) U/ml). No HLA-DR expression was observed with alpha or beta interferon on either malignant squamous cell line, nor with gamma interferon on SW-1271 cells.

Recombinant gamma interferon differentially regulates class II antigen expression and biosynthesis on cultured normal human keratinocytes.

Recombinant gamma interferon induces class II antigen (HLA-DR) biosynthesis and expression on normal cultured human keratinocytes. HLA-DR expression was not induced on keratinocytes by recombinant alpha or beta interferons in a similar dose range nor by Con A or PHA. HLA-DR (L243) expression, as determined by FACS analysis, was detected as early as 1-2 days after addition of r-IFN-gamma to the cultures and was maximal after 4-8 days.

Role of macrophage D-region antigens and T-lymphocyte differentiation antigens in induction of gamma interferon.

Macrophage-T-lymphocyte cultures from patients with recent recurrent herpes labialis were stimulated to produce gamma interferon by either herpes simplex antigen or mitogens (PHA and Con A). The ability of monoclonal antibodies to HLA-DR and DC/DS, HSV glycoprotein antigens and T-lymphocyte surface antigens to inhibit interferon production and lymphocyte proliferation were studied. Anti-D region antibodies inhibited HSV antigen-induced but not mitogen-induced interferon and proliferation.

Antiproliferative effects of recombinant alpha- and gamma-interferons on cultured human keratinocytes.

To extend our initial observation that recombinant gamma-interferon induced expression of class II major histocompatibility (HLA-DR) antigen on normal cultured human keratinocytes, we studied the antiproliferative effects of recombinant alpha- and gamma-interferons. Both interferons reduced the number of attached cells (dose range 10-10(3) units/ml; 7.1 X 10(-11) to 7.

Interferon enhances antibody-dependent cellular cytotoxicity when suboptimal concentrations of antibody are used.

Polymorphonuclear leukocytes (PMN) and killer (K) cells isolated from buffy coats from normal volunteers were tested for antibody-dependent cellular cytotoxicity (ADCC) against chicken erythrocytes (CRBC) with and without the addition of interferon (IFN). Maximum enhancing activity was found when the anti-CRBC antibodies in the ADCC reaction were at suboptimal concentrations. All three species of pure recombinant Escherichia coli-derived interferon were compared for their ability to enhance ADCC in both effector systems.

Recombinant gamma interferon induces HLA-DR expression on cultured human keratinocytes.

In normal human epidermis, expression of HLA-DR antigen is restricted to Langerhans cells (LC) and acrosyringial epithelium. However, in diseases such as lichen planus and graft-vs.-host, HLA-DR antigen appears to be expressed by keratinocytes, although the exact source of the HLA-DR is unclear.

Regulation of expression of class II major histocompatibility antigens on human peripheral blood monocytes and Langerhans cells by interferon.

Although normal peripheral blood monocytes from different individuals are primarily DR+ (L243), they vary in the mean expression of L243 and the percentage of cells with detectable Leu-10 (DC/DS) and L03 (D). All three species of human recombinant IFNs enhance Ia expression on normal peripheral blood monocytes; however, r-IFN-gamma is much more effective in enhancing the expression of these three class II antigens in vitro than r-IFN-beta or r-IFN-alpha A. In addition, r-IFN-gamma has a more profound effect on the expression of Leu-10 (DC/DS), an antigen critical for presentation in autologous MLR, than on L243 (DR).

Recombinant interferon-gamma increases HLA-DR synthesis and expression.

It has been shown that all three classes of interferons enhance the expression of the major histocompatibility class I antigens (HLA-A,B,C;H-2) on a wide variety of cell types (1-10). However, their effect on the expression of the class II antigens (HLA-DR, Ia), which play a major part in cellular interactions that initiate an immune response, is more controversial. The predominate findings have been that the interferons specifically increase the synthesis and expression of only the class I antigens (3, 4, 6, 8, 10, 11).

Interferon increases HLA synthesis in melanoma cells: interferon-resistant and -sensitive cell lines.

We report that human leukocyte interferon preparations increase the expression of beta 2-microglobulin by 100-200% on the surface of normal fibroblast and melanoma cell lines sensitive to interferon. This increase in expression can be correlated with an increase in HLA synthesis as measured by incorporation of [35S]methionine in these antigens. This enhanced HLA synthesis, which is 5- to 17-fold, is time dependent and dose related.