Metabolism of ganciclovir and cidofovir in cells infected with drug-resistant and wild-type strains of murine cytomegalovirus

Murine cytomegalovirus (MCMV) has been used extensively as an animal model for human cytomegalovirus (HCMV). Understanding drug resistance and its treatment in MCMV may lead to more effective treatments of HCMV disease. Most ganciclovir-resistant HCMV clinical isolates exhibit a decreased capacity to induce ganciclovir phosphorylation (to its biologically active form) in infected cells. Using an MCMV strain resistant to both ganciclovir and cidofovir, the intracellular metabolism of these drugs was studied to determine if MCMV resistance correlates with decreases in drug phosphorylation. The wild-type (WT) MCMV used for comparison was inhibited in plaque reduction assays, by ganciclovir and cidofovir by 50% at 5.1 and 0.24 microM, respectively; the resistant strain was inhibited at 72 and 2.7 microM, respectively. In uninfected, WT, or resistant virus-infected cells, the extent of metabolism of 10 microM ganciclovir or 1 microM cidofovir to intracellular triphosphorylated species was similar. Phosphorylation and catabolism (following drug removal) rates over time were also similar. Intracellular levels of ganciclovir triphosphate and cidofovir diphosphate increased less than two-fold with increasing multiplicity of virus infection. Because few differences in drug phosphorylation between WT and resistant virus-infected cells were found, virus resistance to ganciclovir and cidofovir apparently is not linked to altered drug phosphorylation. Since the viral DNA polymerase is the antiviral target for these compounds, the resistant MCMV is most likely a DNA polymerase mutant.

Echinacea-induced cytokine production by human macrophages

Echinacea purpurea, a plant originally used by native Americans to treat respiratory infections, was evaluated for its ability to stimulate the production of cytokines by normal human peripheral blood macrophages in vitro. Commercial preparations of echinacea fresh pressed juice and dried juice were tested at concentrations ranging from 10 micrograms/ml to 0.012 microgram/ml and compared to endotoxin stimulated and unstimulated controls. Cytokine production was measured by ELISA after 18 h of incubation for IL-1 and 36 and 72 h for TNF-alpha, IL-6, and IL-10. Macrophages cultured in concentrations of echinacea as low as 0.012 microgram/ml produced significantly higher levels of IL-1, TNF-alpha, IL-6 and IL-10 (P < 0.05) than unstimulated cells. The high levels of IL-1, TNF-alpha, and IL-10 induced by very low levels of echinacea are consistent with an immune activated antiviral effect. Echinacea induced lower levels of IL-6 in comparison to the other cytokines measured. These results demonstrate the immune stimulatory ability of the unpurified fresh pressed juice of Echinacea purpurea and offer some insight into the nature of the resulting immune response as compared to endotoxin.

Association of genes within the major histocompatibility complex with attention deficit hyperactivity disorder

The objective was to determine whether a relationship exists among the complement C4B gene, a DR region gene and attention deficit hyperactivity disorder (ADHD). Thirty-one subjects with ADHD, their mothers, all but 5 of their fathers, and 90 normal subjects living in northern Utah were studied. DR and C4B typing were performed by serologic HLA typing techniques and the DNA methods PCR-RFLP. The alleles of 2 genes, the null allele of the C4B gene and the beta 1 allele of the DR gene, encode for products involved in immune function and regulation. Each of these alleles was found to be significantly associated with ADHD. Moreover, approximately 55% of the ADHD subjects carried both of these alleles on 1 of their chromosomes, compared to only 8% of normal controls. Genes related to the immune system may be associated with development of the symptoms of ADHD.

Strong association of the third hypervariable region of HLA-DR beta 1 with autism

We reported that the major histocompatibility complex (MHC) including the null allele of the C4B gene and the extended haplotype B44-C30-DR4 is associated with autism. We report now that the third hypervariable region (HVR-3) of certain DR beta 1 alleles have very strong association with autism. The HVR-3 of DR beta 1* 0401 or the shared HVR-3 alleles DR beta 1* 0404 and DR beta 1* 0404 and DR *0101, was expressed on extended haplotypes in 23 of 50 (46%) autistic subjects as compared to only 6 of 79 (7.5%) normal subjects. Another HVR-3 sequence, the DR beta 1* 0701 allele, was carried on extended haplotypes in 16 (32.0%) of the autistic subjects as compared to 8 (10.1%) of the normal subjects.

Immunogenetic studies in autism and related disorders

The major histocompatibility complex comprises a number of genes that control the function and regulation of the immune system. One of these genes, the C4B gene, encodes a product that is involved in eliminating pathogens such as viruses and bacteria from the body. We previously reported that a deficient form of the C4B gene, termed the C4B null allele (no C4B protein produced) had an increased frequently in autism. In this study we attempted to confirm the increased incidence of the C4B null allele in autism and investigated the presence of a C4B null allele in two other childhood disorders, attention-deficit hyperactivity disorder and dyslexia (reading disability). In addition, we explored the relationship of autism to the DR beta 1 gene, a gene located close to the C4B in autism. We confirmed the finding of an increased frequency of the C4B null allele in autism and found that the related disorders also had an increased frequency of this null allele. In addition, two alleles of the DR beta 1 gene also had significantly increased representation in the autistic subjects.

Elevated serotonin levels in autism: association with the major histocompatibility complex

Two of the most consistently observed biological findings in autism are increased serotonin levels in the blood and immunological abnormalities (including autoreactivity with tissues of the central nervous system). The purpose of this investigation was to determine if any relationship exists between these two sets of observations. Our laboratory has found and confirmed associations of the major histocompatibility complex (MHC) with autism. Since the MHC is known to regulate the immune system and is also associated with autoimmune disorders, we studied serum serotonin levels in 20 autistic subjects with or without MHC types previously found to be associated with autism. A positive relationship was observed between elevated serotonin levels and the MHC types previously associated with autism.

Is decreased blood plasma concentration of the complement C4B protein associated with attention-deficit hyperactivity disorder?

OBJECTIVE

The complement system is a group of blood proteins that play an important role in defending against viral and bacterial infections. The objective of this investigation was to study the plasma levels of the C4B protein in attention-deficit hyperactivity disorder (ADHD) in an attempt to associate infections with the development of some cases of this disorder.

METHOD

C4B plasma protein levels were studied using an enzyme-linked immunosorbent assay in a group of 23 subjects meeting DSM-III-R criteria for ADHD and a similar number of age- and sex-matched controls. Also studied were parents of the ADHD subjects.

RESULTS

C4B plasma levels (157.0 micrograms/mL) in the ADHD subjects were significantly (p < .01) lower than those (239.3 micrograms/mL) in the normal age-matched subjects. Mothers of the ADHD subjects also had significantly lower C4B values compared with mothers of normal children. On the other hand, C4B values in the fathers were not significantly altered.

CONCLUSIONS

Decreased C4B levels in ADHD, if replicated, may represent an important marker for ADHD (or a subgroup of ADHD). It also seems plausible that C4B levels are an important etiological factor for ADHD.

Effect of methionine enkephalin on natural killer cell and cytotoxic T lymphocyte activity in mice infected with influenza A virus

Methionine enkephalin (Met-Enk) was evaluated for efficacy as an immune activator and potential therapeutic agent in influenza A/NWS/33 (H1N1) viral infections in female BALB/C mice. Influenza infection was induced intranasally with an approximate 90% lethal dose of virus and mice were treated intraperitoneally with doses of 10, 3 and 1 mg/kg/day, with treatments given 24 h pre-, 24 h post- and 72 h post-virus exposure. Splenocytes were assayed for natural killer cell (NK) and cytotoxic T lymphocyte (CTL) activity at time periods 76, 96 and 120 h post virus exposure. The 10 mg/kg dosage level significantly increased both CTL and NK activity at all time periods assayed. Other treatment schedules included single doses of 20, 10 and 3 mg/kg/day Met-Enk at either 24 h post- or 72 h post-virus exposure, with highly significant increases in NK and CTL activity noted after the latter treatment. The results of this study demonstrate the immunomodulatory effects of Met-Enk on NK and CTL in influenza infected mice and suggest a potential for therapeutic applications.

Leukocyte Interleukin, Inj. (LI) augmentation of natural killer cells and cytolytic T-lymphocytes

A serum free lymphokine preparation derived from human buffy-coat mononuclear cells [buffy coat interleukins (BC-IL)], also named Leukocyte Interleukin, Inj. (LI), trade name Multikine, containing glycosylated interleukin-2 (IL-2) among other interleukins, was tested in three head and neck cancer patients. They responded with tumor regressions associated with increased tumor infiltration of lymphocytes and tumor cell lysis indicating an LI Interleukin-2 induced tumor-specific immune response. To determine whether these responses elicited by LI were IL-2 driven, augmentation of natural killer cells (NKC) and cytolytic T cells (CTL), was tested both in vitro and in vivo. A single intraperitoneal (i.p.) injection of LI in adult BALB/c mice at doses of 3, 10, 30 and 100 of IL-2 equivalence International Units per mouse, led to significant (p < 0.01) augmentation of NKC cytotoxicity to YAC tumor cells. NKC cytotoxicity remained elevated for 7 days, peaking at 5 days post-treatment. Multiple treatments with LI did not increase NKC cytotoxicity above single injection, nor did it lead to NKC hyporesponsiveness. The most effective treatment routes leading to heightened NKC cytotoxicity were: intravenous(i.v.) > intraperitoneal (i.p.) > intramuscular (i.m.) > subcutaneous (sc). Significant (p < 0.05 to < 0.01) NKC cytotoxicity was achieved by all four routes. In vitro incubation of murine splenocytes with 30 and 100 International Units/ml (IU/ml) of IL-2 equivalent elevated NKC cytotoxicity significantly (p < 0.01) at all effector to target cell ratios tested and exceeded the response achieved with rhIFN gamma. NKC cytotoxicity of human peripheral blood lymphocytes (HPBL) against the K562 human tumor cell was also significantly elevated (p < 0.01) at the 30 and 100 IU/ml doses and (p < 0.05) at 3 and 10 IU/ml doses. Of particular interest was the significant increase of CTL response in HPBL generated by LI. Significant activity (p < 0.01) was achieved with levels of 10, 30 and 100 IU/ml at effector to target cell ratios as low as 6 to 1. These results indicate that the LI containing IL-2 led to the significant increase in NKC and CTL cytolytic activities. Relatively lower doses of LI were needed to attain equivalent cytolytic activities as achieved with rhIL-2 or rhIFN gamma.

Antiviral activity of an immunomodulatory lipophilic desmuramyl dipeptide analog

BCH-527, the lipophilic hydrochloride salt of octadecyl D-alanyl L-glutamine, was evaluated for efficacy against experimentally induced murine cytomegalovirus (MCMV), influenza A (H1N1) (IV-A), and Punta Toro virus (PTV) infections in mice. The compound was administered i.p. every other day for a total of 4 injections commencing 24 h previrus exposure. Doses ranged from 12.5 to 200 mg/kg per injection in the various experiments. The MCMV infection was significantly inhibited in two experiments by doses of 25-200 mg/kg, as manifested by increased numbers of survivors and decreased titers of virus recoverable from tissues. The IV-A infection was weakly inhibited, with antiviral activity seen in lowered lung scores and lung weights and less decline in arterial oxygen saturation values. The PTV infection was not inhibited. BCH-527 was stimulatory to cytotoxic T-cells, natural killer (NK) cells, macrophages, and splenic B-cells. The highest dose tested, 200 mg/kg, was inhibitory to cytotoxic T-cell activity and to some extent to NK cell and macrophage activity. These data suggest BCH-527 functions as an immune modulator in exerting the observed antiviral activity.

Effect of the combination of interferon-alpha and stavudine on Friend virus infections in (B10.A x A.By)F1 mice

The anti-Friend leukemia virus (FLV) effects of interferon-alpha-A/D (IFN-alpha) and 2',3'-didehydro-2',3'-dideoxythymidine (stavudine) used alone and in combination were examined in Mus dunni cells using a checkerboard-type experiment design. Strong antiviral synergy and a suggested cytotoxic synergy were seen. In two experiments to evaluate the effect of combining therapy with IFN-alpha and stavudine against FLV disease in the hybrid mouse strain (B10.A x A.By)F1, which is a strong producer of cytotoxic T cells, the drug combination resulted in better inhibition of FLV disease than did either drug used alone. Combination therapy inhibited splenomegaly, splenic virus infectious centers, plasma virus, and the virus-induced increase in hematocrit to a greater degree than did either drug alone. These data indicate that combination therapy with stavudine and IFN-alpha is effective in the treatment of murine retrovirus infections and may be of value in the treatment of human AIDS.

DR-positive T cells in autism: association with decreased plasma levels of the complement C4B protein

Autism is a developmental disorder characterized by severe communication, social and behavioral abnormalities. Over the past several years a fair amount of evidence has accumulated suggesting that some cases of autism may be associated with immune abnormalities and with products of the HLA complex including the C4B gene located in the class III region of HLA. This study sought additional evidence for an association of autoimmune processes with autism by investigating the presence of activated T cells in 26 autistic subjects. Fourteen of the autistic subjects had DR+ T cells, an indicator of activated T cells, but none of the autistic subjects had T cells expressing the interleukin-2 receptor, another indicator of T cell activation. Similar findings of incomplete or partial T cell activation have been reported in autoimmune disorders and in a recent study of autism. In the current investigation, the DR+ T cells were not found to be associated with age of the autistic patients but were inversely correlated with a decreased plasma level of the C4B protein. In conclusion, this study provides additional evidence for the involvement of an autoimmune mechanism in autism.

Increased frequency of the extended or ancestral haplotype B44-SC30-DR4 in autism

Autism likely results from several different etiologies or a combination of pathological mechanisms. Recent studies suggest that this disorder may be associated with immune abnormalities, pathogen-autoimmune processes and perhaps the major histocompatibility complex (MHC). In a preliminary study we found that 22 autistic subjects had an increased frequency of the extended or ancestral MHC haplotype B44-SC30-DR4. The current study attempted to confirm this observation by studying 23 additional randomly chosen autistic subjects, most of their parents and 64 unrelated normal subjects. In agreement with earlier findings B44-SC30-DR4 was associated with autism. In combining the data from the original and current studies, B44-SC30-DR4 or a substantial fragment of this extended haplotype was represented in 40% of the autistic subjects and/or their mothers as compared to about 2% of the unrelated subjects. It is concluded that one or more genes of the MHC is (are) involved in the development of some cases of autism.

Antiviral and immunomodulating inhibitors of experimentally-induced Punta Toro virus infections

A major component of a US Army Medical Research and Development Command-supported program to discover and develop new drugs for the treatment of Rift Valley fever, sandfly fever, and Crimean-Congo hemorrhagic fever has been to study candidate test materials against hepatotropic infections of C57BL/6 mice induced by the related but less biohazardous Punta Toro virus (PTV). The effects of 75 compounds, some of which were considered immunomodulators in their primary mechanism of activity, were studied in the PTV infection model. Of these, ribavirin, ribamidine, ribavirin 2',3',5'-triacetate, tiazofurin, tiazofurin-5'-monophosphate, tiazofurin-2',3',5'-triacetate, selenazofurin, pyrazofurin, 3-deazaguanine, and 3-deazaguanosine were considered significantly inhibitory, acting against the infection by a direct antiviral (non-immunomodulatory) fashion. These compounds had therapeutic indices (TI) ranging from > or = 5 to 65, using increased survivors as the evaluation parameter. Immunomodulators considered significantly inhibitory to this infection were poly (ICLC), ampligen, human recombinant interferon-alpha-A/D, MVE-1, MVE-2, AM-3, AM-5, mannozym, bropirimine, CL246,738, phenyleneamine, and 7-thia-8-oxoguanosine. Utilizing increased survivor numbers as measure of activity, these inhibitors had TI ranging from > or = 16 to 1000. Other antiviral effects exerted by the active compounds included reduction of hepatic icterus, lowered serum glutamic oxaloacetic and pyruvic acid transaminases, and inhibition of recoverable serum and liver virus titers. The active immunomodulators were significantly effective when therapy was initiated as late as 48 h after virus inoculation, at a time when clinical signs of the PTV disease were being manifested in the animal.

Decreased plasma concentrations of the C4B complement protein in autism

OBJECTIVE

To determine complement C4 protein concentrations in the plasmas of autistic subjects and their family members.

DESIGN

Cross-sectional study.

SETTING

Center for Persons with Disabilities and the Department of Biology, Utah State University, Logan.

PARTICIPANTS

Forty-two autistic subjects (34 males [81%] and eight females [19%]), 50 of their biologic parents, 21 siblings, and 105 normal subjects (56 females [53%] and 49 males [47%]; all white) living in northern Utah.

INTERVENTIONS

None.

METHODS

The enzyme-linked immunosorbent assay was used to determine C4 protein concentrations in autistic subjects.

MAIN RESULTS

Plasma concentration (median, 14.7 g/L of the C4B protein) in autistic patients was significantly (P = .01) decreased compared with that of normal subjects (median, 22.4 g/L). The C4B concentrations in parents and siblings of autistic children were decreased, but not significantly. The C4A protein concentrations in the plasma of autistic subjects and their family members were normal.

CONCLUSION

Decreased protein concentrations of C4B may be associated with autism.

Influenza virus-inhibitory effects of intraperitoneally and aerosol-administered SP-303, a plant flavonoid

The phenolic biopolymer SP-303 was evaluated against experimentally induced influenza A (H1N1) virus infections in mice in a series of experiments. When 30, 10 or 3 mg/kg/day of SP-303 were administered intraperitoneally once daily for 8 days beginning either 48 h before or 4 h after virus exposure, only lung consolidation was significantly reduced; extended (p < 0.01) mean day to death was also seen in the late-therapy groups. The high dosage was lethally toxic in this experiment. A small-particle aerosol (SPA) of 10, 5 and 2.5 mg/ml of SP-303, administered for 1 h three times daily for 5 days beginning 4 h after virus exposure, exerted a similar antiviral effect. Twice-daily 1-hour SPA treatments for 3 days beginning 24 h before virus exposure using 4.3 mg/ml of SP-303 resulted in significant increases in mean day to death and reductions of lung consolidation but no inhibition of lung virus titer. Declines in influenza-induced arterial oxygen saturation, as determined by pulse oximetry, were less in all animals treated with SP-303 by SPA, but this reduced decline was significant (p < 0.01) only in the last experiment. Mice receiving SP-303 by SPA exhibited consistent but reversible hypothermia immediately after termination of treatment.

Enhanced proliferation of peripheral blood mononuclear cells and tumor-infiltrating lymphocytes in a plasma-derived cell culture fluid

The proliferation and activation of murine and human T-lymphocytes in a high-protein lymphocyte culture fluid (LCF) is compared to that of cells cultured in 10% fetal bovine serum (FBS). Tumor-infiltrating lymphocytes (TIL) proliferate exponentially in the LCF for up to 46 days and generate cell numbers that are nearly 100,000-fold greater than cells cultured in FBS. This rapid growth of T cells in LCF could have an important impact in adoptive immunotherapy and gene therapy since cell growth is a limiting factor in these technologies.

Immunological effects of amphotericin B and liposomal amphotericin B on splenocytes from immune-normal and immune-compromised mice

The immunological effects of amphotericin B and liposomal amphotericin B were studied in vitro by measuring B- and T-lymphocyte proliferation on splenocytes from immune-normal, cyclosporine-compromised, and cyclophosphamide-compromised mice. Cellular viability of cells from immune-normal mice was also evaluated. The concentrations used (0, 0.5, 1, 2, 4, 8, and 16 micrograms/ml) encompassed clinically relevant doses. Amphotericin B consistently reduced the abilities of B cells and T cells to proliferate, especially when administered at higher than clinically relevant doses. Direct cytotoxicity probably played only a minor role, since viability studies showed that, compared with its liposomal analog, amphotericin B reduced the number of viable cells by no more than 10%. Clinically relevant doses of liposomal amphotericin B (A. S. Janoff, L. T. Boni, M. C. Popescu, S. R. Minchey, P. R. Cullis, T. D. Madden, T. Tarashi, S. M. Gruner, E. Shyamsunder, M. W. Tate, R. Mendelsohn, and D. Bonner, Proc. Natl. Acad. Sci. USA 85:6122-6126, 1988; R. Mehta, G. Lopez-Berestein, R. Hopfer, K. Mills, and R. L. Juliano, Biochim. Biophys. Acta 770:230-234, 1984) did not inhibit any of the immune parameters examined. Liposomes may, therefore, be a useful means of delivering more drug to a host infected with a fungal organism without further compromising the patient's already suppressed immune system.

Immunomodulator effects on the Friend virus infection in genetically defined mice

The disease induced by the Friend virus complex (FV) in F1 hybrid mice containing the Rfv-3r/s genotype in the presence of H-2a/a was used to evaluate a variety of immunomodulating substances. In these genetically defined mice, the FV disease results in splenomegaly, early production of high titers of cell-associated and plasma virus, high levels of splenic viral RNA, increased hematocrit, and eventual death. As the disease progresses, reduced levels of infectious virus correlate with development of specific antibody; reduction in T cell populations, increase in B cells, and decrease in T-cell function also occur. The following immunomodulators were evaluated, listed in the order of their ability to inhibit the FV disease: imexon > MVE-2 > human recombinant IFN-alpha A/D > AS101 > ampligen > AM-3 = oxamisole > ImuVert > bropirimine. In fact, bropirimine, used with certain treatment regimens, appeared to enhance the FV disease. These data suggest that certain immunomodulators may have potential value in the treatment of HIV disease, but also indicate that caution should be exercised in their clinical use.

Murine cytomegalovirus-inhibitory effects of ImuVert

ImuVert, a sterile preparation composed primarily of Serratia marcescens membrane vesicles and ribosomes, was significantly inhibitory to murine cytomegalovirus (MCMV) infections in BALB/c mice. Antiviral activity was manifested as increased survivor number and decreased recoverable virus titers in spleens, lungs and salivary glands. Treatments were intraperitoneal (i.p.) beginning 24 h pre, 4 h post- or 24 h post-virus inoculation and then repeated 4 days later. Doses of 5, 16 or 50 micrograms/mouse were effective; 160 micrograms/mouse, which caused host weight loss in toxicity controls, was not inhibitory to the infection. A single i.p. treatment of mice substantially augmented natural killer (NK) cell activity and increased total B-cells, while reducing total T- and T-helper cells. A late (48 h) decline in T-cell function and transient increases in B-cell function were observed in the treated animals. Serum interferon was not induced. Mice pretreated with anti-asialo GM1 antibody to reduce their NK cell populations, then infected with MCMV and treated with ImuVert were protected to the same degree as normal animals. Severe combined immunodeficient mice infected with MCMV and treated with ImuVert were not protected from the infection. These data suggest ImuVert to act by a mechanism other than NK cell activation in preventing MCMV infections.

Antibodies to myelin basic protein in children with autistic behavior

Based on a possible pathological relationship of autoimmunity to autism, antibodies reactive with myelin basic protein (anti-MBP) were investigated in the sera of autistic children. Using a screening serum dilution of 1:400 in the protein-immunoblotting technique, approximately 58% (19 of 33) sera of autistic children (< or = 10 years of age) were found to be positive for anti-MBP. This result in autistics was significantly (p < or = .0001) different from the controls (8 of 88 or only 9% positive), which included age-matched children with normal health, idiopathic mental retardation (MR) and Down syndrome (DS), and normal adults of 20 to 40 years of age. Since autism is a syndrome of unknown etiology, it is possible that anti-MBP antibodies are associated with the development of autistic behavior.

Effect of immunomodulators in the hu-PBL-SCID mouse model

The effects of two immunomodulators were investigated in severe combined immunodeficient mice reconstituted with human peripheral blood lymphocytes (hu-PBL-SCID mice). Both immunomodulators, maleic anhydride divinyl ether (MVE-2) and 4-imino-1,3-diazobicyclo-(3.1.0)-hexan-2- one (imexon), have been previously studied by us in retrovirus-infected mice. To determine the effects of these compounds as they may function in humans, 24 SCID mice were each reconstituted with 20 x 10(6) ficoll-purified lymphocytes from a single donor. Five weeks after reconstitution, the mice received 16 mg/kg/day of MVE-2 intraperitoneally (i.p.) on days 0, 7, and 14 or 110 mg/kg/day of imexon i.p. daily for 14 days. Spleens were removed and splenocytes labeled with monoclonal antibodies for T- and B-cell enumeration as determined by flow cytometry 24 h after final treatment. Imexon-treated mice demonstrated a slight increase in total T cells and T cell subsets compared to control mice. T helper/T suppressor cell ratios in imexon-treated mice were brought to a normal 3:2 ratio compared to placebo-treated mice. Human immunoglobulin levels were markedly increased in imexon-treated mice. MVE-2-treated hu-PBL-SCID mice had significantly reduced numbers of total T cells compared to controls. The T-cell population results using human cells in SCID mice were similar to the effects of these immunomodulators on murine cells in immunologically competent mice.

Suppression of murine retroviral disease by 2',3'-didehydro-2',3'-dideoxythymidine (D4T)

The thymidine analog, 2',3'-didehydro-2',3'-dideoxythymidine (D4T), and 3'-azido-3'-deoxythymidine (AZT) were evaluated for activity against Friend virus complex (FV) in Mus dunni cells using a focal immunoenzyme assay. The 50% effective doses were, respectively, 1.2 and 0.1 microM for the two compounds; the 50% cytotoxic doses using trypan blue dye exclusion were 25.4 and > 100 microM. Four FV inhibition experiments with D4T were run in F1 hybrid mice containing the Rfv-3r/s genotype. This mouse strain allows the study of treatment effects on development of specific neutralizing antibodies and on splenomegaly, splenic and plasma virus titers, and splenic viral RNA. In the first experiment, D4T was given by oral gavage (p.o.) three times daily (t.i.d.) for 14 days beginning 4 h post-virus inoculation. All dosages used (187.5, 375, 750 mg/kg/day) significantly inhibited all viral parameters. Other experiments used D4T p.o. twice daily, with dosages of 46.9, 93.8, 187.5 and 375 mg/kg/day or four times daily with a dose of 375 mg/kg/day. No significant disease inhibition was seen using the twice daily treatment schedule, but efficacy was apparent using the four times daily treatment. The final experiment repeated the initial study, extending the t.i.d. treatments to 25 days and using dosages of 46.9, 93.8, 187.5 and 375 mg/kg/day. All but the lowest dose reduced each virus parameter. None of the D4T treatment regimens caused death in toxicity controls, although moderate host weight loss or less weight gain was seen, and variable hematocrit decreases occurred, particularly in mice receiving the highest drug dosage. Inhibition of natural killer (NK) cell activity also was seen in these same animals, but in infected mice, FV-induced decrease in NK cell activity was prevented by D4T treatment. Virus-specific neutralizing antibodies developed in all infected, treated animals. These data indicate D4T has potential as a possible candidate for anti-human immunodeficiency virus evaluations in the clinic.

Murine retroviral disease-enhancing effects of a pyrimidinone immunomodulator

(B10.A x A/WySn)F1 mice, infected with the Friend virus (FV) complex, were used as a predictive therapeutic model for AIDS. These infected mice exhibit many of the viral and immunologic manifestations of AIDS. Bropirimine (2-amino-5-bromo-6-phenyl-4[3H]pyrimidinone, ABPP) is an immunomodulating compound which has been shown to inhibit other viral infections. Oral (per os treatment) dosages of ABPP ranging from 50 to 400 mg/kg/day for 3 days resulted in increased numbers of infectious centers in the infected mice and increased splenomegaly and percentage of Ig+ (B cells) in spleens of infected and uninfected mice. Decreased percentages of total Thy-1.2+ (total T) cells and L3T4+ (T-helper) cells were seen in both uninfected and infected mice and a slightly decreased percentage of Ly-2+ (T-suppressor/cytotoxic) cells was observed in spleens of the infected mice. No effect on Ly2+ cells in spleens of uninfected mice was found. Intraperitoneal injection, single or multiple, of 20-200 mg/kg ABPP prior to FV injection resulted in increased spleen weights but had no effect on numbers of infectious centers in the spleens or on FV antibody titers in the plasma. Intraperitoneal treatment of uninfected mice with ABPP resulted in slight or no changes in percentages of Thy-1.2+, L3T4+ and Ly-2+ cells. Mice receiving multiple exposures of ABPP had an increase in percentage of splenic B cells and a depressed response to the T cell mitogen PHA. Treatment with ABPP induced the production of interferon (IFN); however, a state of hyporesponsive IFN production was seen following multiple administrations of ABPP. These data suggest that the immunomodulator ABPP may have an enhancing effect on this retroviral disease.

Possible association of the extended MHC haplotype B44-SC30-DR4 with autism

We previously reported that the complement C4B null allele appears to be associated with infantile autism. Since the C4B null allele is known to be part of the extended or ancestral haplotype [B44-SC30-DR4], we investigated the incidence of [B44-SC30-DR4] in 21 autistic children and their parents. This extended haplotype was increased by almost six-fold in the autistic subjects as compared with healthy controls. Moreover, the total number of extended haplotypes expressed on chromosomes of autistic subjects was significantly increased as compared with those expressed on chromosomes of healthy subjects. We conclude that a gene related to, or included in, the extended major histocompatibility complex may be associated with autism.

Effect of triacontanol on numbers and functions of cells involved in inflammatory responses

A preparation of a triacontanol-containing compound was studied for its effect on cells involved in the inflammatory response. C57BL/6 mice were injected intraperitoneally with various concentrations of this compound and investigated for total body weight, wet weight of thymus tissue, number of thymus cells and splenocytes, interleukin 1 production of spleen monocytes, and response of splenocytes to the T cell mitogen, phytohemagglutinin. Mice treated with the triacontanol preparation exhibited decreased total body weight, 24% reduction in thymus weights, 39% decrease in the number of thymus cells, and 21% depression in total splenocytes. Splenic monocytes of these animals produced a significantly reduced amount of interleukin 1 and splenocytes had a significantly depressed response to phytohemagglutinin. It is concluded that triacontanol has an inhibitory effect on at least some of the cells responsible for inflammation.

Potential role of immunomodulators for treatment of phlebovirus infections of animals

Rift Valley fever (RVFV) is a major phlebovirus-induced epizootic disease of domestic animals (primarily cattle and sheep) in Africa. No therapies for the disease are known. A related phlebovirus, Punta Toro virus (PTV), has been adapted to induce an RVFV-like disease in C57BL/6 mice. This PTV infection has been used as a model for RVFV because it is reasonably safe and does not require high-level biologic containment. The infection model has been used to study the potential role of immunomodulating substances as therapies. A spectrum of immunomodulators has been studied; those immunomodulators most capable of preventing death and other disease manifestations are ampligen, bropirimine, poly (ICLC), AM-3, P-136, and 7-thia-8-oxoguanosine. An immunologic parameter common to all these substances has been their ability to induce interferon. Timing studies have indicated that these active substances may be administered therapeutically as well as prophylactically to inhibit markedly the progress of the disease. Further work is needed in the development of these materials for use in treating viral infections in domestic animals. As a next step, studies need to be run to compare the immunologic profiles induced by each substance in domestic animals and in mice.

Elucidation of mode of retroviral-inhibitory effects of imexon through use of immune competent and severe combined immune deficiency (SCID) mice

Mice infected with various tumor retroviruses have been used as models for evaluating therapeutic substances for the treatment of some cancers, and more recently, for human immunodeficiency virus (HIV) infection, the causative agent of acquired immune deficiency syndrome (AIDS). Consequently, there is a need to determine the ability of biological response modifiers (BRMs) to specifically reduce virus-infected cells, as compared to their non-specific anti-proliferative effects. To address this need, a BRM, imexon, was evaluated in this study using three strains of mice having different Friend virus (FV)-specific immunological capabilities. The first strain, (B10.A x A/WySn)F1, was genetically capable of producing FV-specific neutralization and cytotoxic antibodies, the second, Balb/c, was not, and the third, SCID mice, lacked functional T and B cell immunity. Imexon treatment reduced virally-induced splenomegaly in all 3 strains; however, the concentration of splenic viral infectious centers (IC) were not affected. Since imexon was efficacious in reducing splenomegaly in SCID mice, the mode of action was concluded to not require functional T or B cell immunity. The observation that imexon did not affect splenic IC titers also suggested that imexon did not specifically eliminate virally infected cells, but may have functioned by other mechanisms. This study also demonstrated the use of various mouse strains as a strategy for delineating the modes of action of BRMs against murine retroviral infections.

Utilization of pulse oximetry for the study of the inhibitory effects of antiviral agents on influenza virus in mice

Pulmonary disease in mice induced by influenza virus was monitored by measurement of oxygen saturation (SaO2) in blood with a pulse oximeter. The SaO2 declined in inverse proportion to the viral inoculum. The known antiviral agent ribavirin inhibited the SaO2 decline, prevented death, lowered lung consolidation, and reduced the level of recoverable virus. Pulse oximetry is an effective means of monitoring murine influenzal disease and can be used in the study of potential antiviral drugs.

Changes of soluble interleukin-2, interleukin-2 receptor, T8 antigen, and interleukin-1 in the serum of autistic children

Immune abnormalities in autistic children led us to study for indirect evidence of immune activation as measured by the serum analysis of soluble interleukin-2 (sIL-2), interleukin-2 receptor (sIL-2R), T8 antigen (sT8), and interleukin-1 (sIL-1). The serum concentration of these soluble antigens was quantitated by enzyme-linked immunosorbent assays. The concentration of sIL-2 and sT8, but not of sIL-2R and sIL-1, antigens was significantly (P less than 0.05) increased in the sera of autistic children over that in the control healthy children or children with mental retardation (non-Down's syndrome). This finding indirectly indicates that the activation of a subpopulation of T cells occurs in some children with autism.

Resistance of C57Bl/6 mice to immunosuppressive effects of aflatoxin B1 and relationship with neuroendocrine mechanisms

Aflatoxin B1 (AFB1) a secondary metabolite of Aspergillus flavus and A. parasiticus, is known for its carcinogenicity and immunosuppressive effects. We previously reported on the immunosuppressive effects of AFB1 in Swiss and CD-1 mice. This study concerned the involvement of the hypothalamus-pituitary-adrenal gland axis in the immunosuppressive effects of AFB1 in C57Bl/6 mice. Animals were treated orally with 30, 150 or 750 micrograms/kg AFB1 daily for four weeks. Splenic lymphocytes were assayed to investigate their phenotyping using flow cytometry, proliferative response against mitogens and allogeneic lymphocytes, cytolytic cell activity, and IL-2 production. Antibody-mediated immunocompetence was checked using sheep red blood cell (SRBC)-challenged animals by plaque-forming cell assay and enzyme-linked immunosorbent assay. The dose of AFB1 for the immunosuppressive effects on blastogenic response, IL-2 production, and primary antibody production of splenic cells was much higher than previous studies involving other mice strains. AFB1 decreased the amount of circulating anti-SRBC antibody, and the helper-T cell and B cell populations in phenotyping splenic lymphocytes. There were no significant changes in natural killer cell activity, mixed lymphocyte response, hypothalamic biogenic amine concentrations, and corticotropin releasing factor, and of adrenocorticotropic hormone and corticosterone in plasma. Results were confirmed using adrenalectomized mice. The hypothalamic-pituitary-adrenal axis does not appear to have a major role in AFB1-induced immunotoxicity.

Effect of human, recombinant interleukin 2 on Punta Toro virus infections in C57BL/6 mice

The effect of human recombinant interleukin-2 (rIL-2) on Punta Toro virus (PTV) infection was investigated in C57BL/6 mice. Immunologic and viral parameters were assessed after mice were treated i.p. with rIL-2 for 5 days. Treatment of mice with 25000 and 12500 units/mouse of rIL-2 resulted in significant inhibition of the disease as indicated by increases in survival of mice as well as decreases in liver and serum virus titers. Serum glutamic oxalic acid and pyruvic acid transaminase levels were also lowered indicating reduced liver damage. Murine IL-2 production returned to normal or above-normal levels in rIL-2 treated mice. Natural killer cell activity was also moderately stimulated by rIL-2 treatment. Significant amounts of interferon were not detected in the sera of treated mice. Weight gain and survival rates were similar for both toxicity and normal controls indicating that rIL-2 treatments had no toxic effect.

Increased frequency of the null allele at the complement C4b locus in autism

Associations between C4 deficiency and autoimmune disorders have been found over the past several years. Since autism has several autoimmune features, the frequencies of null (no protein produced) alleles at the C4A and C4B loci were studied in 19 subjects with autism and their family members. The autistic subjects and their mothers had significantly increased phenotypic frequencies of the C4B null allele (58% in both the autistic subjects and mothers, compared with 27% in control subjects). The siblings of the autistic subjects also had an increased frequency of the C4B null allele, but this increase was not significant. The fathers had normal frequencies of this null allele. All family members had normal frequencies of the C4A null allele, all normal C4A and C4B alleles and all BF and C2 alleles.

Effect of imexon treatment on Friend virus complex infection using genetically defined mice as a model for HIV-1 infection

Imexon (4-imino-1,4-diazobicyclo-3.1.0-hexan-2-one) was moderately effective in the treatment of a retroviral infection in a genetically defined murine model. The animal model consisted of a Friend virus complex (FV) infection in a hybrid mouse strain, (B10.A x A/WySn)F1, which has similarities with acquired immune deficiency syndrome (AIDS). Intraperitoneal imexon initiated 1 or 3 days after FV inoculation and continued through 13 days after inoculation significantly reduced splenomegaly, splenic cell-free virus titers and viral RNA. Viral infectious centers/10(6) splenocytes and FV titers in the plasma were reduced, though not to a statistically significant level. The effect of imexon on survival was not statistically significant which suggested that the antiviral effects were only transiently effective. Phytohemagglutinin-induced blastogenesis and percent of total T cells, T helper cells and T suppressor/cytotoxic cells in the spleens were increased, and the percentage of B cells decreased by imexon treatment of both FV-infected and uninfected mice. The splenic natural killer cell activity and interleukin-1 production were not markedly affected. Virus specific neutralizing antibody developed in both imexon- and placebo-treated FV-infected mice, although titers were lower in the imexon-treated animals.

Binding of [3H]serotonin to lymphocytes in patients with neuropsychiatric disorders

Based on recent studies of neuroimmune networks, the lymphocyte binding of serotonin neurotransmitter was studied in patients with Alzheimer's disease, idiopathic mental retardation, and autism. The specific binding to lymphocytes of [3H]serotonin, at a single concentration of 100 nM, was significantly reduced in Alzheimer's disease patients as compared to aged controls (group mean of 3.667 +/- 2.301 v 7.506 +/- 1.717 picomoles; p = 0.001), and in children with idiopathic mental retardation as compared to healthy children (group mean of 3.694 +/- 1.627 v 5.792 +/- 1.902 picomoles; p = 0.003). However, autistic children did not differ significantly from the healthy children (group mean of 5.287 +/- 1.987 v 5.792 +/- 1.902 picomoles; p = 0.475). Reduced lymphocyte binding of serotonin may be an indication of breakdown of an unknown neuroimmune pathway relevant to the pathophysiology of Alzheimer's disease and idiopathic mental retardation.

Detection of maternal antibodies in infantile autism

Maternal antibodies reactive with antigenic proteins expressed on the cell surface of paternal lymphocytes can be detected in couples with histories of more than one miscarriage or stillbirth. It is possible, but not proven, that these antibodies also react with tissues of the fetus and result in fetal death. Since many mothers of autistic children have a history of pregnancy disorder, antibodies were studied in 11 mothers of autistic children who were 6 years of age or younger. Six of the mothers had antibodies that reacted with lymphocytes of the autistic child. Five of these six mothers had a history of pregnancy disorder. Since antigens expressed on lymphocytes are found on cells of the central nervous system and, perhaps, other tissues of the developing embryo, it is suggested that aberrant maternal immunity may be associated with the development of some cases of infantile autism.

CD4+ helper T cell depression in autism

CD4+ (helper) T cells are a heterogenous population of lymphocytes including at least two distinct subpopulations. To investigate the possibility that immune abnormalities in some subjects with autism may involve abnormal distributions of CD4+ and/or CD8+ cells, (suppressor) T cells, peripheral blood lymphocytes of 25 autistic subjects were characterized with monoclonal antibodies and flow cytometry. The autistic subjects had a significantly lower percentage and number of CD4+ cells, a lower number of T cells (CD2+ cells) and B cells (CD20+ cells), and a lower percentage and number of total lymphocytes than siblings and normal subjects. The level of blood values for female subjects appeared lower than those for males as compared to normal subjects of the same sex. These results suggest that a decrease in CD4+ cells is associated with autism.

Deficiency of suppressor-inducer (CD4+CD45RA+) T cells in autism

CD4+ cells are a heterogenous population of lymphocytes including at least two distinct subpopulations: CD45RA+ cells, inducers of suppressor T cells and CDw29+ cells, inducers of helper function for antibody production. To investigate the possibility that immune abnormalities in autism may involve abnormal distribution of these helper subpopulations, monoclonal antibodies were used in flow cytometric analysis to characterize peripheral blood lymphocytes of 36 subjects with autism. The autistic subjects as compared to a group of 35 healthy age-matched subjects had a significantly reduced number of lymphocytes, a decreased number of CD2+ T cells and reduced numbers of CD4+ and CD4+CD45RA+ lymphocytes. The numbers of B (CD20+) cells, suppressor T (CD8+) cells, inducers of helper function (CD4+CDw29+) and natural killer (CD56+) cells were not altered in the autistic subjects. Our results suggest that an alteration in the suppressor-inducer T-cell subset is associated with autism.

Effect of oxamisole on immune parameters of mice infected with murine hepatitis

The effects of Oxamisole, 2,3,5,6,7,8-hexahydro-2-phenyl-8,8- dimethoxyimidazo[1,2a]pyridine on immune parameters of mice infected with murine hepatitis were investigated. Young Swiss Webster mice were injected intraperitoneally (i.p.) with the Friend-Braunsteiner strain of murine hepatitis virus and with various doses of Oxamisole at 48 h pre- 24 h pre-, and 4 h post-virus exposure. Antiviral activity was seen in the drug-treated mice which was approximated on the basis of 21-day survival frequency and hepatic discoloration, SGOT and SGPT levels and amount of infectious virus recoverable from the liver. On day 4 post-viral exposure, splenic cells from some of the drug- and placebo-treated cells of infected mice injected with Oxamisole, 25 mg/kg/day, produced significantly more interleukin-1 and interleukin-2 than cells of infected mice treated with saline only. Similarly, mice treated with 25 mg/kg/day of this compound had cells with significantly increased antibody-dependent cell-mediated cytotoxicity as compared with placebo treated animals. However, cells from mice treated with Oxamisole did not demonstrate altered natural killer cell activity. It is concluded that Oxamisole, when administered to mice infected with murine hepatitis virus, has antiviral properties which possibly are mediated through the immunomodulatory effects of this compound on the immune system.

Altered T-cell subsets and defective T-cell function in young children with Down syndrome (trisomy-21)

Children with Down syndrome (DS) suffer an increased incidence of severe viral and bacterial infections particularly during the first 5 years of life. Unfortunately, few studies have been performed on the immune systems of young children with Down syndrome. Peripheral blood mononuclear cells (PBMC) from a group of non-institutionalized children less than 6 years of age were studied and compared with PBMC from age-matched controls. The children with DS had reduced numbers of circulating OKT4+ (helper/inducer) T cells and a significantly depressed ratio of OKT4+ to OKT8+ (suppressor/cytotoxic) T cells. PBMC from the DS subjects exhibited reduced proliferative responses to phytohemagglutinin and to an optimal concentration of concanavalin A (Con A), but normal responses to suboptimal doses of Con A and pokeweek mitogen. PBMC from young children with DS appeared to produce normal levels of interleukin-2 (IL-2). These findings provide evidence that the primary immune defect in DS is in part a depressed number and function of helper T cells. They also indicate that IL-2 production may not be defective in DS, but rather that the mechanism for response to IL-2 may be faulty.

Inhibition of murine hepatitis virus infections by the immunomodulator 2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxy-imidazo[1,2a]pyridine (PR-879-317A)

PR-879-317A (2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxy-imidazo [1,2a]pyridine) has been found to be a T-cell-selective immunomodulating agent. In the current studies, a series of experiments was designed to determine the potential antiviral activity of this compound in mice infected with murine hepatitis virus. In a comparative antiviral experiment, the activity seen was superior to that of levamisole, a known immunorestorative agent. This activity was characterized by an increase in the 21-day survival frequency, a decrease in hepatic discoloration, a decrease in the amount of infectious virus recoverable from the liver, and normalization of serum glutamic oxalacetate and pyruvate transaminase levels. A comparison of treatment routes indicated the relative efficacies as intraperitoneal greater than per os greater than intramuscular greater than or equal to subcutaneous. Alteration of the treatment schedule markedly affected the antiviral effect; prophylactic or therapeutic treatments once or twice daily for 3 days were usually effective. Single treatments begun 4 h before or 24 h after virus inoculation were highly efficacious. Three treatments administered on alternate days, beginning 48 h before virus inoculation, proved moderately effective. Thrice-daily treatments were ineffective, as were treatments with durations of greater than 3 days. The optimal dosage varied according to the treatment route and dosage schedule. When assessed for direct antiviral activity in vitro, PR-879-317A failed to demonstrate any significant activity against murine hepatitis virus. The positive in vivo activity noted might therefore be the result of immune modulation rather than a direct antiviral effect.

A natural killer cell assay for the mink using a mouse lymphoma as the target cell line

A natural killer cell assay was developed for the mink (Mustela vison) using mink peripheral mononuclear cells as effector cells and a mouse lymphoma cell line as targets. Baseline levels of natural killer cell activity were established in fertile mutation mink, primary infertile dark mink and secondary infertile dark mink with autoimmune orchitis. Blood samples were taken from dark mink at the end of March and from mutation mink during the first 2 weeks in April. Statistically significant differences in activity were noted between color phases and among groups. The possibility of genetic and/or seasonal differences in natural killer cell activity is discussed.

Effect of phenytoin on antibody production: use of a murine model

An animal model was used to study the effects of phenytoin on immune function. Inbred NFS mice, injected with phenytoin, 10-40 mg/kg, and immunized with bovine serum albumin (BSA), demonstrated a dose-dependent decrease in production of IgG antibodies to BSA. Phenytoin at the dosages used in this study did not appear to be overtly toxic to immune organs and cells as judged by normal weights of thymus and spleen and normal WBC counts of mice injected with phenytoin. In addition, mice receiving phenytoin had normal body weights, liver weights, and hematocrits. The usefulness of an animal model to study immunomodulatory effects of antiepileptic drugs is discussed.

PR 879-317A enhances in vitro immune activity of peripheral blood mononuclear cells from patients with Down syndrome

Down syndrome is associated with immune deficiencies which result in increased incidences of respiratory infections and lymphocytic leukemia. Peripheral blood mononuclear cells (PBMC) from patients with Down Syndrome were assayed in several in vitro assays following incubation in medium or various concentrations of PR 879-317A (2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxyimidazo (1,2a) pyridine), a selective immunorestorative agent. PBMC of the patients, incubated in medium, exhibited significantly reduced activities in the natural killer (NK) cell, antibody-dependent cell-mediated cytotoxicity (ADCC), T-cell blastogenesis and leukocyte-inhibition factor (LIF) assays. Incubation in PR 879-317A significantly increased the NK and ADCC activities of PBMC from both patients and healthy subjects. However, the effect was much more pronounced on the patients' cells increasing their NK and ADCC activities to normal levels. Incubation in PR 879-317A augmented to normal levels the responses of patients' cells in various assessments of T-cell immunity including blastogenic responses to phytohemagglutinin and concanavalin A and production of LIF. In addition, the number of patients' cells forming spontaneous rosettes with sheep red blood cells was increased following incubation in PR 879-317A. In contrast this compound did not significantly modify the T-cell responses of cells from the healthy subjects suggesting that this compound does not affect normal T-cell function.

Effects of phenytoin and carbamazepine on human natural killer cell activity and genotoxicity in vitro

Human peripheral blood mononuclear cells (PBMC) were isolated from healthy volunteers and exposed in vitro to phenytoin or carbamazepine, two widely used antiepileptic drugs (AED). This study investigated the effects of these drugs on natural killer (NK) cell activity and antibody-dependent cell-mediated cytotoxicity (ADCC), which are both thought to protect against developing neoplasms. Also, the genotoxicity of phenytoin on human PBMC was investigated by gravity-flow alkaline elution. Concentrations of phenytoin considered therapeutic (10 and 20 micrograms/ml) and a dose considered acutely toxic (40 micrograms/ml) were used while carbamazepine levels of 8 micrograms/ml (therapeutic) and 10 and 16 micrograms/ml (acutely toxic) were tested. Phenytoin at all three concentrations significantly suppressed NK cell activity in a dose-dependent manner. Carbamazepine had no significant effect on NK cell activity at the dose levels studied. Incubation in propylene glycol, the diluent for carbamazepine, significantly decreased NK cell activity compared to saline. Phenytoin also significantly depressed interferon augmentation of NK cell cytotoxicity in a dose dependent manner. ADCC activity was significantly depressed with 20 and 40 micrograms/ml phenytoin. Alkaline elution showed a slight but significant increase in DNA single-strand breaks of PBMC exposed to 40 micrograms/ml phenytoin for 18 or 72 hr. These results show phenytoin may induce pronounced immunosuppression of NK cell and ADCC activity in patients receiving antiepileptic therapy and that this agent has a potential for genotoxic side effects. Phenytoin may also increase the potential for neoplasm development by a direct interaction with cellular DNA and/or an indirect mechanism by immunosuppression.