The Role of MicroRNAs in Regulatory T Cells and in the Immune Response

The discovery of microRNA (miRNA) is one of the major scientific breakthroughs in recent years and has revolutionized current cell biology and medical science. miRNAs are small (19~25nt) noncoding RNA molecules that post-transcriptionally regulate gene expression by targeting the 3' untranslated region (3'UTR) of specific messenger RNAs (mRNAs) for degradation of translation repression. Genetic ablation of the miRNA machinery, as well as loss or degradation of certain individual miRNAs, severely compromises immune development and response, and can lead to immune disorders. Several sophisticated regulatory mechanisms are used to maintain immune homeostasis. Regulatory T (Treg) cells are essential for maintaining peripheral tolerance, preventing autoimmune diseases and limiting chronic inflammatory diseases. Recent publications have provided compelling evidence that miRNAs are highly expressed in Treg cells, that the expression of Foxp3 is controlled by miRNAs and that a range of miRNAs are involved in the regulation of immunity. A large number of studies have reported links between alterations of miRNA homeostasis and pathological conditions such as cancer, cardiovascular disease and diabetes, as well as psychiatric and neurological diseases. Although it is still unclear how miRNA controls Treg cell development and function, recent studies certainly indicate that this topic will be the subject of further research. The specific circulating miRNA species may also be useful for the diagnosis, classification, prognosis of diseases and prediction of the therapeutic response. An explosive literature has focussed on the role of miRNA. In this review, I briefly summarize the current studies about the role of miRNAs in Treg cells and in the regulation of the innate and adaptive immune response. I also review the explosive current studies about clinical application of miRNA.

MicroRNAs in Human Diseases: From Lung, Liver and Kidney Diseases to Infectious Disease, Sickle Cell Disease and Endometrium Disease

MicroRNAs (miRNAs) are a class of naturally occurring small non-coding RNAs of about 22 nucleotides that have recently emerged as important regulators of gene expression at the posttranscriptional level. Recent studies provided clear evidence that microRNAs are abundant in the lung, liver and kidney and modulate a diverse spectrum of their functions. Moreover, a large number of studies have reported links between alterations of miRNA homeostasis and pathological conditions such as infectious diseases, sickle cell disease and endometrium diseases as well as lung, liver and kidney diseases. As a consequence of extensive participation of miRNAs in normal functions, alteration and/or abnormalities in miRNAs should have importance in human diseases. Beside their important roles in patterning and development, miRNAs also orchestrated responses to pathogen infections. Particularly, emerging evidence indicates that viruses use their own miRNAs to manipulate both cellular and viral gene expression. Furthermore, viral infection can exert a profound impact on the host cellular miRNA expression profile, and several RNA viruses have been reported to interact directly with cellular miRNAs and/or to use these miRNAs to augment their replication potential. Here I briefly summarize the newly discovered roles of miRNAs in various human diseases including infectious diseases, sickle cell disease and enodmetrium diseases as well as lung, liver and kidney diseases.

MicroRNAs in Human Diseases: From Autoimmune Diseases to Skin, Psychiatric and Neurodegenerative Diseases

MicroRNAs (miRNAs) are small noncoding RNA molecules that negatively regulate gene expression via degradation or translational repression of their target messenger RNAs (mRNAs). Recent studies have clearly demonstrated that miRNAs play critical roles in several biologic processes, including cell cycle, differentiation, cell development, cell growth, and apoptosis and that miRNAs are highly expressed in regulatory T (Treg) cells and a wide range of miRNAs are involved in the regulation of immunity and in the prevention of autoimmunity. It has been increasingly reported that miRNAs are associated with various human diseases like autoimmune disease, skin disease, neurological disease and psychiatric disease. Recently, the identification of mi- RNAs in skin has added a new dimension in the regulatory network and attracted significant interest in this novel layer of gene regulation. Although miRNA research in the field of dermatology is still relatively new, miRNAs have been the subject of much dermatological interest in skin morphogenesis and in regulating angiogenesis. In addition, miRNAs are moving rapidly onto center stage as key regulators of neuronal development and function in addition to important contributions to neurodegenerative disorder. Moreover, there is now compelling evidence that dysregulation of miRNA networks is implicated in the development and onset of human neruodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Tourette's syndrome, Down syndrome, depression and schizophrenia. In this review, I briefly summarize the current studies about the roles of miRNAs in various autoimmune diseases, skin diseases, psychoneurological disorders and mental stress.

MicroRNAs in Human Diseases: From Autoimmune Diseases to Skin, Psychiatric and Neurodegenerative Diseases

MicroRNAs (miRNAs) are small noncoding RNA molecules that negatively regulate gene expression via degradation or translational repression of their target messenger RNAs (mRNAs). Recent studies have clearly demonstrated that miRNAs play critical roles in several biologic processes, including cell cycle, differentiation, cell development, cell growth, and apoptosis and that miRNAs are highly expressed in regulatory T (Treg) cells and a wide range of miRNAs are involved in the regulation of immunity and in the prevention of autoimmunity. It has been increasingly reported that miRNAs are associated with various human diseases like autoimmune disease, skin disease, neurological disease and psychiatric disease. Recently, the identification of mi- RNAs in skin has added a new dimension in the regulatory network and attracted significant interest in this novel layer of gene regulation. Although miRNA research in the field of dermatology is still relatively new, miRNAs have been the subject of much dermatological interest in skin morphogenesis and in regulating angiogenesis. In addition, miRNAs are moving rapidly onto center stage as key regulators of neuronal development and function in addition to important contributions to neurodegenerative disorder. Moreover, there is now compelling evidence that dysregulation of miRNA networks is implicated in the development and onset of human neruodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Tourette's syndrome, Down syndrome, depression and schizophrenia. In this review, I briefly summarize the current studies about the roles of miRNAs in various autoimmune diseases, skin diseases, psychoneurological disorders and mental stress.

MicroRNAs in Human Diseases: From Cancer to Cardiovascular Disease

The great discovery of microRNAs (miRNAs) has revolutionized current cell biology and medical science. miRNAs are small conserved non-coding RNA molecules that post-transcriptionally regulate gene expression by targeting the 3' untranslated region of specific messenger RNAs for degradation or translational repression. New members of the miRNA family are being discovered on a daily basis and emerging evidence has demonstrated that miRNAs play a major role in a wide range of developmental process including cell proliferation, cell cycle, cell differentiation, metabolism, apoptosis, developmental timing, neuronal cell fate, neuronal gene expression, brain morphogenesis, muscle differentiation and stem cell division. Moreover, a large number of studies have reported links between alterations of miRNA homeostasis and pathological conditions such as cancer, psychiatric and neurological diseases, cardiovascular disease, and autoimmune disease. Interestingly, in addition, miRNA deficiencies or excesses have been correlated with a number of clinically important diseases ranging from cancer to myocardial infarction. miRNAs can repress the gene translation of hundreds of their targets and are therefore well-positioned to target a multitude of cellular mechanisms. As a consequence of extensive participation in normal functions, it is quite logical to ask the question if abnormalities in miRNAs should have importance in human diseases. Great discoveries and rapid progress in the past few years on miRNAs provide the hope that miRNAs will in the near future have a great potential in the diagnosis and treatment of many diseases. Currently, an explosive literature has focussed on the role of miRNA in human cancer and cardiovascular disease. In this review, I briefly summarize the explosive current studies about involvement of miRNA in various human cancers and cardiovascular disease.

The Role of Regulatory T Cells in Cancer

There has been an explosion of literature focusing on the role of regulatory T (Treg) cells in cancer immunity. It is becoming increasingly clear that Treg cells play an active and significant role in the progression of cancer, and have an important role in suppressing tumor-specific immunity. Thus, there is a clear rationale for developing clinical strategies to diminish their regulatory influences, with the ultimate goal of augmenting antitimor immunity. Therefore, manipulation of Treg cells represent new strategies for cancer treatment. In this Review, I will summarize and review the explosive recent studies demonstrating that Treg cells are increased in patients with malignancies and restoration of antitumor immunity in mice and humans by depletion or reduction of Treg cells. In addition, I will discuss both the prognostic value of Treg cells in tumor progression in tumor-bearing hosts and the rationale for strategies for therapeutic vaccination and immunotherapeutic targeting of Treg cells with drugs and microRNA.

Cytokine Production in Patients With Leprosy / 나학회지

No abstract available.

The Role of Suppressor T Cells in Mycobacterial Infection / 나학회지

Suppressor T cells (Ts cells) once became probably the most controversial topic in the field of immunology. However, recently the picture has changed dramatically. Suppressor T cells, now less provocatively renamed regulatory T cells (Treg cells) are isolated and can be expanded in vitro and in vivo and their role is the subject of intensive investigation. It is now well recognized that Treg cell is central components of fundamental immune functions such as self-tolerance, anti-tumor response, T cell homeostasis, allergic and autoimmune diseases, allograft transplantation and control of infection. Although regulatory T cells play a crucial role in the control of immune responses to bacteria, fungus, virus and parasites, little is known about the role of Treg cells in mycobacterial infections. Here, I briefly describe 1)the biology of Treg cells, 2)induction and expansion of pathogen-specific Treg cells, 3)beneficial and detrimental roles of Treg cells in infection and 4)"Old Friends" mechanism of hygiene hypothesis. This article also explores observations on Treg or Ts cells in mycobacterial infectious diseases such as leprosy and tuberculosis. I finally summarize the potential for Treg-targeted immunotherapy in infectious diseases allergic and autoimmune diseases as well as transplantation and anti-tumor immunity. The correct balance of effector/pathogenic and regulatory T cells for successful immunotherapeutic approach is also emphasized.

Regulatory T Cell Therapy for Autoimmune Disease

It has now been well documented in a variety of models that T regulatory T cells (Treg cells) play a pivotal role in the maintenance of self-tolerance, T cell homeostasis, tumor, allergy, autoimmunity, allograft transplantation and control of microbial infection. Recently, Treg cell are isolated and can be expanded in vitro and in vivo, and their role is the subject of intensive investigation, particularly on the possible Treg cell therapy for various immune-mediated diseases. A growing body of evidence has demonstrated that Treg cells can prevent or even cure a wide range of diseases, including tumor, allergic and autoimmune diseases, transplant rejection, graft-versus-host disease. Currently, a large body of data in the literature has been emerging and provided evidence that clear understanding of Treg cell work will present definite opportunities for successful Treg cell immunotherapy for the treatment of a broad spectrum of diseases. In this Review, I briefly discuss the biology of Treg cells, and summarize efforts to exploit Treg cell therapy for autoimmune diseases. This article also explores recent observations on pharmaceutical agents that abrogate or enhance the function of Treg cells for manipulation of Treg cells for therapeutic purpose.

Bacteriocin ("vulnificin") typing of Vibrio vulnificus

Vibrio vulnificus, a halophilic vibrio is an estuarine gram-negative bacteria that is associated with severe and frequently fatal wound infections and life-threatening septicemia. Bacteriocins are defined as antibacterial substance produced by various species of bacteria which are usually active against closely related organisms. Bacteriocins have found widespread application in epidemiological studies as specific markers of bacteria. It was proposed by Ha et al. (1990. J. Korean. Soc. Microbiol. 25: 586.) to give the bacteriocins produced by V. vulnificus the name "vulnificins". In the present study, a total of 72 strains of V. vulnificus isolated from patients and oysters were subjected to screen potential producers and indicators of vulnificin, applying ultraviolet induction method. Sensitivity of several strains of Serratia marcesans, Pseudomonas aeruginosa, Shigella flexneri, Salmonella typhi and Yersinia enterocolitica to vulnificins were also examined out. All the tested strains of V. vulnificus produced vulnificins active against indicator strains with various different inhibitory patterns. The spectrum of vulnificin activity and sensitive spectrum of indicator strains were considerably broad. Interestingly, almost all strains of S. marcescens, P. aeruginosa, Salmonella sp., Shigella sp. and Y. enterocolitica tested were sensitive to 1-7 vulnificin(s). Taken together, the present study demonstrated that all of the isolates of V. vulnificus produced vulnificins and that 8 good vulnificin producers and 10 good indicators were detected. These strains can be employed efficiently for establishing vulnificin typing scheme of V. vulnificus and for the detection of bacteriocinogeny and sensitivity in V. vulnificus. Biological role of vulnificin remains to be further elucidated.

Effects of Capsaicin Pretreatment on the Functions of Mouse Peritoneal Macrophages / 대한면역학회지

No abstract available.

Effects of Sensory Denervation by Neonatal Capsaicin Treatment on Cytokine Production and Various Immune Responses / 대한면역학회지

Capsaicin, the pungent principle of hot peppers, is a neurotoxin that depletes unmyelinated primary sensory neurons (polymodal nociceptors) of neuropeptides like tachykinins. However, the role of capsaicin-sensitive sensory nerve in the production of cytokines, penicillin V (PEV)-induced active fatal anaphylaxis and other immune responses is not yet fully established. Neonatal mice were pretreated s.c. with a single injection of 10 ug of capsaicin per mouse in volume of 20 ul within 5 days of age. Using 5-8 week old mice pretreated as neonates with capsaicin, the capsaicin- pretreated and vehicle-treated control mice were examined for various parameters of immune responses described above. For the induction of active fatal anaphylaxis with PEV, 8 week old mice pretreated as neonates and age-matched capsaicin- untreated control mice were sensitized i.p. with 500 ug of PEV-ovalbumin conjugate plus 2*10(9) B. pertussis and 1.0 mg alum and challenged i.v. with PEV-bovine serum albumin conjugate 14 days later. It was found that neonatal capsaicin-pretreatment significantly enhanced contact hypersensitivity to TNCB and hemagglutination response to SRBC, but significantly inhibited the proliferation response of rnurine splenocyte to Con A and LPS. Interestingly, neonatal capsaicin pretreatment significantly inhibited the intensity of PEV-induced active fatal anaphylaxis and decreased the mortality due to anaphylactic shock. It also significantly inhibited LPS- induced production of cytokines such as TNF-a, IL-1B, IL-6, IL-10, and IL-12. The capsaicin-pretreatment also resulted in an inhibition of the activation of NF-kB. Taken together, these data showed for the first time that neonatal capsaicin-pretreatment significantly inhibited an antibiotic (PEV)-induced anaphylaxis and production of various cytokines, and suggest that capsaicin-sensitive primary sensory nerve may play an important regulatory role in active fatal anaphylaxis and cytokine production, thus potentially presenting tools for immune intervention. In particular, the data presented also indicated the possibility to selectively down-modulate cytokine production and NF-kB activation may offer a broad application for therapeutic intervention in neuroimmunological diseases and other pathological situations.

Effect of Human Seminal Plasma on Cytokine Prodection and Induction of Active Systemic Anaphylaxis in Mice / 대한면역학회지

Human seminal plasrna (HSP) is mixture of secretion derived from various glands associated with male reproductive tract which comprises approximately 80-90% of the volume of normal ejaculate. The present study was undertaken in an effort to explore the effect of HSP pretreatment on the production of IL-1B, TNF-a and IL-12, in mice, and to investigate if HSP may cause to induce active systemic anaphylaxis (ASA) in mice. In addition, effects of HSP pretreatment on contact hypersensitivity to trinitrochlorobenzene (TNCB), antibody response to polyvinylpyrroridone (PVP), a thymus-independent antigen and on ASA induced by egg albumin (OVA) were also studied in this study. For the experiments of contact hypersensitivity, antibody response and cytokine production, mice were pretreated i.p. daily with 0.3ml of HSP or sterile saline alone (control) for 3 consecutive days before antigen sensitization or lipopolysaccharide injection for the cytokine induction. For the experiments of OVA- induced anaphylaxis, mice were pretreated by a single s.c. injection of HSP 0.3ml per mouse before sensitization. For induction of ASA in mice by HSP, a group of mice were sensitized i.p. 2 consecutive days with 0.3ml of HSP and one day with 0.3 ml of HSP plus 2x10(9) B. pertussis and 1.0 mg of alum (schedule A) or another group of mice were sensitized i.p. with a single i.p. injection of 0.3 ml of HSP with 2x10' B. pertussis and 1.0 mg of alum (schedule B). All sensitized and unsensitized control mice were challenged i.v. with 0.2ml of HSP 14 days after HSP sensitization, and mortality were observed. It was found that HSP pretreatment inhibited the production of IL-lB, TNF-a and IL-12, and also inhibited OVA-induced ASA, contact hypersensitivity to TNCB and anti-PVP antibody production. Interestingly, ASA was induced by HSP irrespective of the applied sensitization schedule. Taken together, this study may provide the direct evidences that HSP may inhibit the production of IL-1B, TNF-a and IL-12 and this may be the first to show the induction of ASA by HSP in mice.

Effect of Alcohol Administration on Production of Cytokines, Salmonella Infection and Penicillin V - Induced Anaphylaxis in Mice / 대한면역학회지

The present study was undertaken to investigate the effect of acute administration of ethanol on production of cytokines such as IL-1j3, IL-2, IL-6, IL-10 and TNF-a, induction of penicillin V-induced active fatal anaphylaxis, and resistence to Salmonel/a typhimurium infection in mice. Ethanol administration into mice was performed by intraperitoneal injection of 0.5 ml of 20 % ethanol for 3 consecutive days before induction of cytokines with lipopolysaccharide (LPS), Con A or Salmone/la injection. Serum levels of cytokines were measured by ELISA. It was found that ethanol administration significantly inhibited both the serum levels of all cytokines examined and the resistance of mice to S. typhimurium. However, ethanol administration failed to prevent penicillin-induced fatal anaphylaxis. Taken together, the present results may need new insights in the diagnosis and treatment of various immunologically-mediated diseases.

Effects of Capsaicin on Production of Cytokines and Nitric Oxide, Salmonella Infection and NF-kappa B Activation / 대한면역학회지

"Capsaicin, the pungent principle of hot peppers, is a neurotoxin that depletes primary sensory neurons of neuropeptides like tachykinin. The objectives of these experiment was to examine the effects of capsaicin on Salmonel/a typhimurium-induced production of cytokines such as TNF-a, IL-1B, IL-6, IL-10 and IL-12 and on production of nitric oxide in peritoneal macrophages. In addition, the effects of capsaicin on survival rates of S. typhimurium-infected mice and on nuclear transcription factor (NF-kB) activation were also investigated. Mice were pretreated with a single s.c. injection of 100 ug of capsaicin and were infected i.v. with S. typhimurium (5xO5/mouse) in 0.2 ml volume after capsaicin pretreatment. The serum cytokine levels were measured 30, 60, 120, 180 and 240 min after Salmonella infection, using ELISA kits. The activation of NF-B was also examined by gel shift assay in spleens, thymuses and brains of mice that had been pretreated with a single s.c. injection of 100 ug of capsaicin. It was found that Sa/mone/la infection induced the production of TNF-a, IL-1B, IL-6, IL-10 and IL-12, but capsaicin pretreatment inhibited the production of TNF-a, IL-1B, IL-10 and IL-12, but enhanced IL-6 production 120 min after Salmonella infection. Interestingly, the capsaicin pretreatment inhibited the activation of NF-kB in spleens and thymuses. There were no differences in the numbers of bacteria in livers, brains, spleens, kidneys and lungs between capsaicin- pretreated mice and the control animals in applied experimental conditions. Suprisingly, however, capsaicin pretreatment increased both the survival rates of Sa/mone//a-infected mice and production of nitric oxide by peritoneal macrophages compared with capsaicin-untreated control mice. Taken together, these results indicate that the capsaicin-sensitive primary sensory neurons may play an important modulatory role in the production of cytokine, nitric oxide and NF-B activation and the pathogenesis of salmonellosis."

Effects of Alcohol Administration on Cytokines, Nitric Oxide, Infection Anaphylaxis and Melanoma Growth / 대한면역학회지

The present study was undertaken to investigate the effect of ethanol administration on the resistance of mice to Cryptococcus neoformans, IL-2 production of murine splenocytes, active systemic anaphylaxis induced by ovalbumin (OVA), serum TNF-alpha production, nitric oxide (NO) production by peritoneal machrophages and B16F10 melanoma colonization in lungs in mice. It was found that ethanol administration significantly inhibited the resistance of mice to C. neoformans infection, IL-2 production, active systemic anaphylaxis induction, serum TNF- alpha production and NO production. Ethanol administration significantly enhanced lung colonization when it was administered before i.v. melanoma inoculation. These results demonstrate that ethanol may play a critical role in tumorigenesis and immunoregulation as an immunomodulator.

Effects of Cytokines on Proliferation Responses of Th1 Cells to Mitogen / 대한면역학회지

Thl cloned cell line 28-4 which is an I-A + KLH - specific Th1 type clone of (C57BU6xC 3H) F1 origin was kindly provided by professor Tomio Tada. In these studies, employing these cloned cells, the author investigated both proliferation responses of Thl cells in the presence of various concentrations of cytokines, such as IL-2, IL-4 or IL-6 and proliferation of Thl cells to various concentration of mitogens such as PHA, ConA or PWM. In addition, the author also investigated the proliferation response of Th1 cells to the optimal dose of PHA, ConA or PWM in the presence or absence of above mentioned cytokines. It was found that IL-2, IL-4 or IL-6 alone their growth stimulation degree was dependent on cytokine concentration and that PHA, ConA or PWM stimulated Thl cell proliferation and optimal dose of PHA ConA and PWM was 3 g, 4 g and 2 g per ml, respectively. In addition, proliferation response of Th1 cells to ConA or PWM in the presence of IL-2 was significantly enhanced, but the proliferation response to PHA was not increased significantly. However, IL-4 did not significantly modulate mitogen-activated Thl cell proliferation response. Interestingly, IL-6 decreased PHA- or ConA-activated proliferation of Thl cells, but did not change PWM-activated proliferation. Taken together, these studies strongly suggested that IL-2, IL-4 or IL-6 itself clone stimulated the Thl cell proliferation and that PHA, ConA or PWM also stimulated Thl cell proliferation. In addition, these studies also indicated that IL-2 increased ConA- or PWM-activated Thl cell proliferation, but IL6 inhibited PHA- or ConA-activated Th1 cell proliferation and that IL-4 did not significantly change the mitogen-activated Th1 cell proliferation.

Effects of an Opiate Receptor Antagonist Naloxone on Endotoxic Shock and Tumorigenesis / 대한면역학회지

Septic shock is one of the leading cause of death in hospitalized patients and mortality rates of up to 50 % have been reported. Despite all efforts, no regimen today seems to be successful in the treatment of septic shock. The endogenous opioid system (EOS) includes three major families of peptides: dynorphins, endorphins and enkephalins. Several lines of evidence indicate that EOS is implicated in the pathophysiology of anaphylactic and endotoxic shock. An opioid receptor blocker naloxone has been used extensively in studies for the role of EOS or endogenous opiod peptides (EOP). However, there have been few, if any, detailed investigative studies regarding the effect of naloxone on TNF-a production and the lethality in response to endotoxin, and tumorigenesis. ...continue...

Effect of Capsaicin on Immune Responses, Anaphylaxis and Tumorigenesis in Mice / 대한면역학회지

It has been known that the interconnection between the gervous, endocrine and immune system are largely mediated through regulatory soluble factors such as neruopeptides, cytokines and hormones. Capsaicin, the pungent principle of hot peppers, is a neurotoxin that affects primary sensory neurons of the C and A-b type and depletes primary sensory neurons (polymodal nociceptors) of neuropeptides like tachykinin. In this study capsaicin was used to explore the possible role of the neruons on the expression of cellular and humoral immune responses and TNF-a prodcution. Mice were pretreated with s.c. injections in the neck region with a single dose of 100 u,g of capsaicin per mouse before immunization. ...continue...

Anti-IL-4 antibody inhibits antigen specific IgE response but fails to prevent chicken gamma globulin-induced active systemic anaphylaxis: evidence for the involvement of IgG antibodies

It has recently been reported that interleukin-4 (IL-4) is required for the production of IgE, and anti-IL-4 monoclonal antibody (mAb) inhibits in vivo IgE responses. These suggest that blocking of IL-4 activity may be useful for the prevention or treatment of immediate hypersensitivity disorders. In this study we investigated whether anti-IL-4 has a regulatory role in chicken-gamma globulin (CGG)-induced active systemic anaphylaxis. Multiple injections of anti-IL-4 (up to 40 mg/mouse) failed to protect the mice from fatal anaphylaxis. Anti-IL-4 strongly suppressed CGG-specific IgE response (>90%) without any suppressive effect on CGG-specific IgG (IgG1, IgG2a, IgG2b, and IgG3) responses. Because these data suggest the possibility that fatal anaphylaxis could be induced by IgG antibodies, we examined the possibility using anti-CGG polyclonal and the subclasses of IgG monoclonal antibodies. Passive sensitization of mice with polyclonal antibodies elicited severe and fatal anaphylactic shock; about 50% of the mice died. The activity of antibodies was not diminished by heat treatment (56 degrees C, 2h), suggesting that the anaphylaxis was not mediated by IgE. Shock was also elicited by each subclass of IgG mAb; of these, IgG1 was the most effective. Combination of the IgG subclasses elicited more exaggerated shock; about 30% of mice died. These data indicate that IgG antibodies are themselves sufficient to induce systemic anaphylaxis. Therefore, the failure of anti-IL-4 to prevent active anaphylaxis is probably due to the inability of anti-IL-4 to suppress the production of IgG antibodies.