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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). We report here that recombinant interferon-gamma (IFN-gamma) increases the synthesis and expression of the HLA-DR (la-like) antigens as well as beta 2-microglobulin (beta 2-m), a low m.w. subunit of HLA, on human melanoma cells. No increase in HLA-DR was detected on these melanoma cells with leukocyte interferon (IFN-alpha) at doses 400 times higher than the maximum dose of IFN-gamma. These findings were extended to show that pure IFN-gamma also increases the expression of the HLA-DR antigens on normal peripheral blood monocytes, whereas recombinant IFN-alpha at a similar dose had little effect on the expression of this surface antigen. These findings suggest a specialized role for IFN-gamma in immune regulation in comparison with IFN-alpha.

Mouse interferon preparations significantly suppress the in vivo antibody response to sheep red blood cells (SRBC), a thymus-dependent antigen, and to Salmonella typhimurium lipopolysaccharide (LPS), a thymus-independent antigen. It is also possible to effect the late responses of antigen sensitive "memory" cells observed during secondary immunization by administration of interferon prior to primary immunization. The immunosuppressive activity of interferon was time- and dose-dependent. Maximum suppression was produced when animals were given 1.5 times 10-5 units of interferon between 4 and 48 hr before antigenic stimulation. These findings suggested that interferon affects some early event(s) in the process of antibody synthesis which might be related to the general inhibitory effect of interferon on rapidly dividing cells and viral m-RNA translation. In addition, the use of nonadherent spleen cell cultures from interferon-treated mice, immunized in vitro with a thymus-independent antigen, indicated that in this situation the inhibitory effect of interferon was due to an action on B lymphocytes. A variety of soluble "suppressive" factors are secreted by T cells as a consequence of activation by mitogens or specific antigens in vitro. Since T cells are recognized as one of the sources of interferon, it is suggested that interferon should be investigated as a suppressor T cell-produced lymphokine which can regulate B cell expression.

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. These data indicate that there is no relationship between in vitro growth cytostasis/cytolysis and in vivo antitumor response. All three interferon preparations will potentiate both tumor specific and nonspecific monoclonal antibody therapy. Natural MIFN-alpha/beta and recombinant human hybrid interferon-alpha A/D, which should share a common cell surface receptor, had similar antitumor activity in both models. Combining recombinant human hybrid interferon-alpha A/D and rMIFN-gamma therapy was not additive for 38C13 lymphoma and a three-way combination with antiidiotype was not significantly more effective than combination therapy with one interferon type. In general, rMIFN-gamma was more effective in in vivo combination therapy against the s.c. T-cell lymphoma than against the i.p. B-cell lymphoma and was more synergistic with anti-Thy1.1 than with antiidiotype.

The effect of interferon on mouse and human in vitro erythropoiesis was investigated using the mouse marrow CFU-E and the human blood BFU-E systems, respectively. Homologous interferons were found to have a marked inhibitory effect on mouse CFU-E and human BFU-E proliferation. This inhibitory effect was dose related and independent of the erythropoietin concentration used. The effective concentration of human interferon was within the range observed in humans following viral infections. It is suggested that interferon may play a role in the mechanism of the acute erythroblastopenic crisis observed at times in patients with chronic anemia following viral infections.

Human peripheral blood lymphocytes, highly enriched for T cells, were obtained by passing gravity-sedimented leukocytes through nylon wool columns. The eluted cells were cultured with autologous macrophages and the mixture was studied for its capacity to produce interferon in vitro in response to stimulation with herpes simplex virus antigen. The interferon produced by the combined macrophage-lymphocyte cultures was shown to depend upon the presence of T cells; elimination of these cells by treatment with an anti-T cell serum plus complement greatly diminished the amount of interferon produced. The memory for the immune-specific release of interferon also appeared to be carried by the T lymphocytes rather than the glass-adherent macrophages. Furthermore, the results suggest that under our conditions of culture immune-specific interferon originates from T cells.

Several chemicals and interferons have been utilized in the prophylaxis and the treatment of a number of human herpesvirus infections. For example, adenine arabinoside as well as acyclovir and human leukocyte interferon appear active against acute varicella zoster and herpes simplex infections in controlled trials. Some of these agents have transient in vivo actions against CMV and EBV as well. Further open trial work with these 2 viruses appears necessary to improve dose regimens or to employ combination therapy or study new derivatives or agents before controlled trials are warranted. Recombinant DNA methodology is currently providing much greater yields of pure interferon for such uses. Recent successes in eradicating chronic hepatitis B virus infection suggest that it is even possible in the future that persistent herpesviruses in the CNS or lymphoreticular systems may be amenable to long-term therapy. As hyperimmune globulin appears to diminish the severity of CMV disease, it is also possible that human monoclonal antibodies may provide a useful approach for immunoprophylaxis as therapy.

At different times of exposure, interferon (IFN) enhanced and suppressed pokeweed mitogen- (PWM) induced IgG synthesis by human peripheral blood lymphocytes (PBL). Pretreatment of PBL and IFN frequently increased antibody production by more than 100% when compared with that by untreated PBL. Results of experiments in which PBL were separated into T and B subpopulations indicated that IFN preparations acted directly on B cells. Thus, mixtures of IFN-treated B cells and untreated T cells from 5 of 7 persons tested produced 81% to 500% more IgG than untreated, matched control cells. However, IFN-treated monocytes mixed with untreated B and T cells or IFN-treated T cells mixed with untreated B cells failed to enhance IgG production significantly in similar assays. In contrast to the pretreatment protocol, when IFN was present in the incubation mixture throughout the PWM assay, IgG production decreased. Sephadex chromatography of the IFN and tests of the resulting fractions indicated that the IgG production-enhancing activity was located in the fraction carrying the antiviral activity.

A factor with antiviral activity has been produced in vitro by combined macrophage-lymphocyte cultures from patients with recent herpes labialis in response to HSV antigen stimulation. It has been designated "immune interferon" and characterized in comparison to several other human interferons. It was shown to be relatively unstable at pH 2 and at 56 degrees C. Rabbit anti-human leukocyte interferon serum was shown to be less active against immune interferon than against diploid cell interferon or against vesicle fluid interferon. The possibility of immune interferon being a totally different anti-viral protein or a protein with certain shared antigen determinants or structures with classical viral interferon is discussed. A simplified method for the assay of anti-interferon sera with microtiter plates is also described.

Seventeen patients with disseminated cancer were treated with a human leukocyte interferon preparation in doses ranging from 3 X 10(6) to 50 X 10(6) IU daily for 30 days. Doses above 18 X 10(6) IU were considered intolerable in this schedule of administration due to severe fatigue and weight loss. Serum concentrations of interferon were lower than those achieved with either partially pure native or recombinant leukocyte interferon. Three of 17 patients in this study showed minimal evidence of tumor regression. Two patients treated at doses of 18 X 10(6), 36 X 10(6), and 50 X 10(6) IU also received a 5 X 10(6)-IU dose of a second human leukocyte interferon preparation. The latter resulted in less toxicity but similar serum levels. These results suggest that human leukocyte interferons prepared in the same manner may differ significantly in their in vivo biologic properties.

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. SIR-1, although completely resistant to IFN in vitro, is more sensitive to IFN than the parental cell line in vivo. IFN treatment at 10(4) units, three times weekly, resulted in a 28% increase in mean survival time and a 1.4% long term survival rate in the IFN-sensitive 38C13 cell line but resulted in a 275% increase in mean survival rate and a 27% long term survival rate in the interferon-resistant SIR-1 mutant. Statistical analysis of 38C13 and SIR-1 with and without IFN treatment demonstrate that: a) the SIR-1 mutant remains sensitive to the cytotoxic effects of IFN in vivo (P less than 0.0001); and b) the mean survival and long term survival of animals with the SIR-1 mutant is significantly greater than for animals with the IFN-sensitive 38C13 cell line (P less than 0.0001). Two additional independently isolated IFN-resistant cell lines (SIR-111 and SIR-E102) also demonstrate significantly enhanced in vivo response to IFN compared to the interferon-sensitive parental (38C13) cells. These results indicate that, for this cell line, the antitumor effects of IFN are mediated by activation of host defenses and that resistance to the in vitro cytotoxic effects of IFN results in a tumor phenotype that is more readily recognized by host defenses and eliminated.

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. Anti-idiotype mAb that was cleaved into F(ab')2 fragments no longer had any antitumor activity alone and could not be enhanced by IFN therapy. These results suggest that antibody is functioning through Fc gamma R-bearing effector cells that are enhanced by IFN therapy. Synergy between IFN and anti-idiotype mAb was maintained in nude mice lacking classical T cells but was reduced in C3H beige mice lacking classical NK/killer cells. IFN did not increase idiotype expression on the tumor cells but did increase H-2 expression. Although we have previously shown that rIFN-alpha A/D can directly kill 38C13 in vitro, an IFN-resistant subclone derived from 38C13, SIR-1, was equally or more responsive to human rIFN-alpha A/D in vivo and had a synergistic antitumor response to combination IFN and anti-idiotype therapy, indicating that IFN acts primarily through host mediated effects rather than direct effects.

Our studies of in vitro cellular immune responses to herpesviruses have shown that, before treatment, lymphoma patients have decreased transformation to varicella-zoster virus antigen compared to herpes simplex virus and cytomegalovirus antigens. Interferon production to varicella-zoster virus and cytomegalovirus antigens is also decreased. During the first six months of treatment, decreased lymphocyte transformation and interferon production to all herpesviral antigens was observed. Among patients in long-term remission, recovery from the suppression associated with treatment was noted except that interferon production to varicella-zoster virus antigen remained decreased.

Interferon-gamma (IFN-gamma) was spontaneously secreted by peripheral blood mononuclear cells cultured from patients soon after recurrent herpes labialis (RHL) or was induced from macrophage-T lymphocyte cultures in vitro with HSV antigen. Circulating Leu-3+/Leu-2- cells produced the spontaneous IFN almost exclusively. In the HSV antigen-stimulated culture system the same subset was the predominant producer of IFN-gamma. The IFN-gamma producing leu-3+ lymphocytes were plastic nonaderent but nylon wool adherent, and may be analagous to the murine Th 2 helper cell. In contrast to one lymphocyte subset being the major IFN-gamma producer in this viral disease, mitogen stimulation induced IFN-gamma from all (Leu-2+/2- and Leu-3+/3-) subsets, with panning as the separation technique. As mitogens circumvent the normal processing and presentation of antigen, the RHL system described above may provide a more accurate picture of the relative contributions of helper (Leu-3+) and cytotoxic/suppressor (Leu-2+) T cells to IFN-gamma production in herpes viral disease.

Hepatitis B virus associated DNA polymerase activity, hepatitis b surface antigen (HBsAg), and serum aspartate aminotransferase were followed in 21 patients with chronic active hepatitis while immunosuppressive therapy (prednisone +/- azathioprine) was being withdrawn. In every case, DNA polymerase activity fell within 6-10 wk of decreasing treatment and became undetectable in 8 patients. This was usually accompanied by a fall in HbsAg titer and a transient rise in serum aspartate aminotransferase activity. Four additional patients with previously untreated HbsAg positive chronic active hepatitis were placed on prednisone for 12 wk. There was a rise in DNA polymerase activity and HBsAg titer with a fall in serum aspartate aminotransferase values during treatment. Upon discontinuing therapy, DNa polymerase activity fell dramatically in all 3 patients who completed their course of prednisone and became undetectable in 1. These findings suggest that immunosuppressive therapy has a potentiating effect on hepatitis B viral replication in patients with chronic active hepatitis.

The clinical and immunologic effects of a biosynthetic human leukocyte interferon, recombinant leukocyte A interferon (IFL-rA), are reported in eight patients with advanced cancer. Single escalating doses from 3 X 10(6) units to 198 X 10(6) units were given by intramuscular injection in a phase I study. Major toxic effects included pyrexia, fatigue, myalgia, and headache. Data on the effects of IFL-rA on lymphocyte subpopulations and peripheral blood mononuclear-cell surface beta 2-microglobulin are presented. Four of eight patients had objective tumor regression, indicating that further investigation of this biologically active material is warranted.

Natural killing by mouse spleen cells can be stimulated in vivo by interferon or by agents that stimulate interferon, such as poly I.C. Natural killing can be suppressed in vivo by the sustained administration of 17 beta-estradiol. In BALB/c mice that had been treated with 17 beta-estradiol for 10 weeks, natural killing did not respond to intravenous poly I.C, although stimulation of circulating interferon was equal to controls. Estradiol, then, does not block interferon production but does suppress the response of natural killer cells to interferon. It is suggested that estrogens either block the maturation of natural killer cells or reduce the number of natural killer cell precursors.

Herpes zoster can be a severe, and sometimes fatal, virus infection in its disseminated form in immunocompromised hosts. Previous studies have suggested that delay in appearance of antibody to varicella-zoster virus occurs as one defect in such patients. In this study, pooled gamma-globulin (normal serum globulin [NSG]) and zoster immune globulin ([ZIG] prepared from convalescent zoster patients) were compared for their ability to prevent dissemination of early localized zoster in immunocompromised hosts. Either agent was given intramuscularly in randomized double-blind fashion within nine days of onset of zoster in 97 patients. Despite greater than 100-fold differences in titer of anti-varicella-zoster virus antibody, ZIG did not appear superior to NSG in prophylaxis of dissemination or diminishing postherpetic pain in zoster in immunocompromised hosts. Zoster immune globulins should be reserved for prophylaxis and modification of varicella, where its beneficial effect has been demonstrated.

Two glycoproteins have been identified on human CMV that induce neutralizing antibody; an 86,000-Da glycoprotein and a 130,000-, 92,000-, and 50,000-Da glycoprotein coimmunoprecipitating complex that appears to be the gB homologue of HSV. We have produced syngeneic monoclonal anti-Id antibodies (mAb2) of the IgM isotype to a CMV-neutralizing monoclonal antibody (mAb1) that is known to bind to the 86,000-Da glycoprotein on the virion envelope. These mAb2 bear the internal image of the original viral antigen as shown by their ability to 1) recognize an interspecies idiotype in CMV-positive human antisera, 2) block mAb1 binding to CMV antigen, and 3) block CMV neutralization by mAb1 in vitro. Immunization of mice with both of these affinity chromatography-purified mAb2 stimulated the production of anti-anti-Id monoclonal antibodies (which we termed mAb3), which bound to the mAb2 by ELISA and neutralized CMV infectivity.

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. In contrast, lymphokine-activated killer (LAK)-mediated lysis of P815 showed a linear response to increasing concentrations of rIL 2 both in vitro and in vivo. Transfer of LAK cells did not alter the rate of infection after HSV-2 challenge. Anti-asialo GM-1 eliminated rIL 2 protection against HSV-2 infection. It also blocked HSV-2/HFF lysis and partially decreased P815 lysis in vitro; however, in vivo it inhibited both natural killer (NK) activity and LAK generation, failing to distinguish which of the lytic cells was responsible for the effect against infection. Early IgG production (7 days post-infection) was enhanced by rIL 2 administration before viral inoculation, but it did not influence the rate of infection as compared with controls. Polyclonal IgM secretion was not found to play a role in acute protection. Circulating serum interferon levels were enhanced with increasing concentrations of rIL 2 but did not correlate with the biphasic dose curve for protection. Therefore of these mechanisms the one that is most closely related to the protective effect of rIL 2 against primary HSV-2 infection appears to be NK-mediated lysis, although the other mechanisms may add to this effect.

Twelve patients with cervical intraepithelial neoplasia (CIN) were studied by colposcopy and cervical smears to elucidate the local response to interferon alpha and beta given by perilesional injections and to assess long-term disease remission. In all patients, local inflammatory response was seen and persisted throughout the treatment period. Selective toxic effect was evident by exfoliation of increasing proportion of degenerate to viable dyskaryotic cells, while the normal epithelial cells appeared unaffected, and by the progressive regression of the lesion. Interferon alpha induced complete remission in six of seven (85.7%) patients but three had recurrence 12 to 24 months later, while interferon beta induced complete remission in only two of five (40%) patients.

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 7.1 X 10(-9) M) and gamma-interferon was 100 times more potent than alpha. This effect did not require the presence of Langerhans cells. gamma-Interferon reduced total cell production during the first week without increasing the percentage of cells shed. During the second week, gamma-interferon also increased the percentage of cell shedding. Although 10(2) units/ml of gamma-interferon was maximal for HLA-DR expression by cultured keratinocytes, there was increasing reduction of attached cells between 10(2) to 10(3) units/ml. The demonstration that recombinant gamma-interferon induces HLA-DR expression and also inhibits keratinocyte proliferation in vitro at nanomolar concentration expands the growing list of normal cells whose biologic function may be influenced by this lymphokine in vivo.

Interferons are proteins elaborated by infected cells that protect noninfected cells from viral infection. These proteins produce a temporary "antiviral state" by altering nucleotide metabolism and cytoplasmic enzyme induction. Interferons appear early after viral infection locally and systematically to limit spread of viral infection; they also affect cell differentiation, growth, surface, antigen expression, morphologic findings, and immunoregulation. Several human disorders have diminished interferon production. Newborns have normal interferon alpha but deficient interferon gamma production. Infants with congenital infections may also have defects in interferon production. Immunosuppressed patients receiving transplants (marrow, heart, of kidney) have diminished interferon production, particularly immediately after transplant. Deficiencies of interferon have also been noted in Down's syndrome, cellular immunodeficiencies, uremia, malnutrition, and hematopoietic malignancy. Leukocyte interferon has been of therapeutic value in herpes zoster infections, in patients with cancer, and in patients with hepatitis B infection. Interferon has not been proved to help children with congenital cytomegalovirus or rubella. Interferon can shrink lymphoid tumors, particularly non-Hodgkin's lymphoma.

We determined that recombinant interleukin 2 (rIL-2) administered in conjunction with herpes simplex virus (HSV) crude extract or recombinant glycoprotein D subunit vaccine enhances the protective effect of either antigen preparation against HSV type 2 genital infection in guinea pigs. Animals that received the vaccine accompanied by rIL-2 had an incidence of infection, assessed by detection of clinical lesions and/or viral shedding, that varied between 0 and 43% significantly lower than the incidence of 63 to 100% in guinea pigs submitted to the same immunization schedule without rIL-2. Animals that escaped acute infection failed to develop recurrent disease. In addition, severity of acute infection was decreased by rIL-2 co-administration as well as by increasing the number of vaccine doses. We also studied the immune response of the guinea pigs to vaccination and the mechanism of protection. Both enzyme-linked immunosorbent assay titers of antibodies to HSV type 2 and specific antigen stimulation of lymphocytes measured by proliferation and interferon production did not significantly differ among the immunization groups. However, specific cellular cytotoxicity was enhanced by rIL-2 co-administration and was positively correlated with protection. This suggests that rIL-2 may become an important adjuvant in active immunization programs using subunit vaccines, particularly against diseases in which cellular cytotoxicity is a major defense mechanism.

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). We report here that recombinant interferon-gamma (IFN-gamma) increases the synthesis and expression of the HLA-DR (la-like) antigens as well as beta 2-microglobulin (beta 2-m), a low m.w. subunit of HLA, on human melanoma cells. No increase in HLA-DR was detected on these melanoma cells with leukocyte interferon (IFN-alpha) at doses 400 times higher than the maximum dose of IFN-gamma. These findings were extended to show that pure IFN-gamma also increases the expression of the HLA-DR antigens on normal peripheral blood monocytes, whereas recombinant IFN-alpha at a similar dose had little effect on the expression of this surface antigen. These findings suggest a specialized role for IFN-gamma in immune regulation in comparison with IFN-alpha.

Epstein-Barr virus and hepatitis B virus are two agents which chronically infect man and have been associated with specific neoplasms. Such findings point the way to new methods of control and detection of human malignancies. Furthermore, immunosuppression is another major factor underlying the development of certain malignancies in human populations. It is clear that congenital immunodeficiency states as well as organ transplant recipients requiring iatrogenic immunosuppression and cancer patients requiring chemotherapy and/or x-irradiation are susceptible to particular malignancies at a higher rate than the normal population. Such findings also provide not only clues as to the mechanisms which control tumor development but argue for certain limitations to the extent of immunosuppressive therapy utilized for treatment of cancer.

Peripheral blood mononuclear cells separated from the blood of 29 volunteers within 3 wk of the onset of recurrent oral herpes labialis spontaneously secreted IFN-gamma (and small amounts of IFN-beta) into the culture medium in varying amounts (mean = 77 U/ml, SE = 17). However, interferon could not be detected in the serum of 10 of these patients tested. In the group as a whole, peak levels of interferon were secreted in vitro at 6 to 20 days after the onset of herpes labialis. Serial studies in eight patients showed peak production in the second or third week, with subsequent decrease to undetectable levels at 6 wk. A strong correlation between peak supernatant interferon level and the time to the next recurrence of herpes labialis in each patient was noted (r = 0.82, p less than 0.0001). Herpes simplex antigen-stimulated mononuclear cell cultures from each patient produced a mixture of IFN-alpha and IFN-gamma. A less marked but still significant correlation was noted between the peak mixed interferon level and the inter-recurrence interval (r = 0.52, p less than 0.005). These results suggest that a recurrent herpes labialis acts as an in vivo stimulus to the induction of IFN-gamma-producing cells that circulate in peripheral blood. The IFN-gamma produced is either a direct determinant of frequency of recurrence of herpes or a quantitative marker for other cellular immune events determining frequency.

Understandably, there is interest in further defining the nature of 'non-specific' defenses. This, in fact, would clarify the specific nature of their appearance and action, as well as their role in host defense. Therefore, 'non-specific' defenses in my discussion will be taken to mean non-immune defenses in virus infections. Tissue or respiratory tract organ cultures are convenient means of studying host defenses in the absence of immune responses. Factors to be controlled in making observations with such systems will be discussed which help 'in vitro' results to parallel 'in vivo' findings. 'In vitro' and 'in vivo' methods and results probing importance of mucous barrier, ciliary activity, temperature and pH will be reviewed. Critical points in separating cellular and humoral immune functions from non-specific mediators will also be touched on. This distinction is complicated by the fact that both limbs of immunity work in close concert with macrophages, PMN's complement and other inflammatory responses. Interferon and macrophage mobilization are examples of 'non-specific' responses which have more recently become complicated by their recognition as part of the effector limb of the cell-mediated immune responses. Finally, methods will also be presented for distinguishing human interferon of the immune-specific variety associated with cell-mediated immunity from that produced by viral infection of non-immune cells.

Antigen-specific type II interferon was produced in vitro by harvesting supernatants of spleen cell cultures from Swiss-Webster mice sensitized with Mycobacterium bovis strain BCG and challenged with old tuberculin. Treatment of C3H mouse spleen cell cultures with appropriate anti-Ia, anti-IgG, anti-Thy-1 or anti-Ly-2,3 sera resulted in a significant decrease in production of type II interferon. Removal of nylon wool adherent cells or cells with histamine receptors by column chromatography similarly caused reduced production of type II interferon. Recombination of spleen cell cultures treated with anti-Ia and anti-Thy-1 sera or of cells treated with anti-IgG and anti-Thy-1 resulted in restored production of type II interferon. Interferon production was also restored by combination of cells passed through histamine columns with anti-Ia treated cells, or those passed through nylon wool columns with anti-Thy-1 treated cells. Anti-Ly-1 serum treatment had no effect on interferon production. Removal of plastic-adherent cells or cells that had phagocytosed carbonyl iron also decreased interferon production, suggesting that macrophages were also involved in type II interferon production. Recombination of non-adherent spleen cells with anti-Ia and anti-Thy-1 sera treated spleen cells, however, did not restore interferon production, suggesting that other cells in addition to macrophages are depleted by the adherence procedure. These findings indicate that type II interferon is produced by suppressor or cytotoxic (Ly-2,3+) T lymphocytes in co-operation with one or two additional cell types: (i) B lymphocytes, and (ii) macrophages.

Ten young adult patients with chronic hepatitis B virus infection and positive hepatitis B e antigen and DNA polymerase (DNAP) levels were treated with alternating courses of seven to 28 days of 5 to 7.5 mg/kg of vidarabine monophosphate (adenine arabinoside monophosphate) and 28 days of human leukocyte interferon (IFN-alpha); three different regimens were given on an outpatient basis. All patients with a fall in their DNAP level, and the DNAP remained undetectable six months after treatment was stopped in one patient. The major side effect, which most often occurred in those patients receiving 7.5 mg/kg of vidarabine monophosphate, was severe muscular pains. This study demonstrated the feasibility of administering vidarabine monophosphate and interferon to outpatients. Based on data from this and other studies, it is now possible to use a relatively nontoxic regimen that includes 28 days of 5 mg/kg of vidarabine monophosphate in a larger controlled study to answer the question of efficacy.

This review has attempted to synthesize work on antiviral chemotherapy, particularly pointing up the possibility of immunosuppression by drugs and the importance for antivirals of cooperative effects with immune and nonspecific recovery mechanisms. With the current successes and crucial need for antiviral chemotherapy, it is likely present efforts will be superseded by future work. A particularly attractive possibility which has only just begun to be investigated is the combination of chemo- and immunotherapy.

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. injection of 100 micrograms) and recombinant human hybrid interferon-alpha A/D (10(4) to 10(6) U three times weekly for 3 wk) synergistically increased median survival time in mice challenged with a lethal dose of tumor cells compared with the sum of the median survival times of the two individual treatments. IFN-alpha has direct antiproliferative activity against 38C13 in vitro and enhances in vitro macrophage anti-idiotype antibody-specific cytolysis for IgG2a, IgG2b, and IgG1 isotypes.