The allergic phenotype: manifestation of 'allergic breakthrough' and imbalance in normal 'damping' of IgE antibody production

Studies of serum total immunoglobulin E concentrations in atopic and non-atopic dogs

The serum total immunoglobulin E (IgE) concentrations of two groups of atopic dogs and three groups of non-atopic dogs were compared. There was a wide range of concentrations with a high degree of overlap between the groups. The serum total IgE concentrations of a group of 15 non-atopic racing greyhounds were significantly higher than those of all the other groups. Atopic and non-atopic dogs receiving stringent parasite control treatments could not be differentiated on the basis of their serum total IgE concentrations. In the non-atopic dogs there was no correlation between their serum total IgE concentrations and the number of allergen-specific positive results obtained in an ELISA, or between their serum total IgE concentrations and their age.

Virus associated immune and pharmacologic mechanisms in disorders of respiratory and cutaneous atopy

Anaphylaxis represents non-atopic immediate hypersensitivity, whereas manifestations of atopic immediate hypersensitivity include bronchial asthma, hay fever, allergic rhinitis, chronic urticaria, and atopic dermatitis. In spite similar antigen exposure, only a minority of the population shown some form of atopic disease. Atopic disease with its spontaneous pattern of familial occurrence cannot be induced at will.

The exact pathogenesis of atopy is yet to be elucidated. Two theories prevail: 1) atopy is a primary disorder of the immune system with sequelae in the various effector tissues; and 2) a concept of atopy as a primary autonomic imbalance, essentially beta adrenergic in character, with sequelae in effector cells, including those engaged in the production of antibodies. The autonomic imbalance is perceived as caused not by some disorder of the autonomic nervous system itself but by a defector functioning of its effector cells. These two concepts are not mutually exclusive. The IgE antibody, which mediates allergic reactions, is essentially identical with atopic reagin in various animal species.

The beta adrenergic theory regards atopic disorders (i.e., perennial and seasonal allergic rhinitis, bronchial asthma, and atopic dermatitis) not as immunologic diseases but as unique patterns of altered reactivities to a broad spectrum of immunologic, psychic, infectious, chemical and physical stimuli. The antigen-antibody interaction is given the same role as that of a broad category of nonspecific stimuli that function only to trigger the same defective homeostatic mechanism in the various effector cells involved in immediate hypersensitivities. Current evidence favors the possibility that there are inherited and/or acquired multiple abnormalities in the receptor—adenylate cyclase—cyclic AMP system of all effector cells that are critical in the organization of immune reactivities.

Atopic abnormality may be 1) acquired by functional receptor regulatory shifts caused by hormonal changes, infection (viral, bacterial, etc), allergic tissue injury or other event; 2) genetically determined; or 3) caused by autoimmune disease. One, two or all three of these effector mechanisms may be operative in a particular disease.

There is an important relationship between asthma and viral respiratory infection. A history of childhood viral respiratory illness is a risk factor for the development of chronic obstructive airway syndromes in later life. Asthmatic attacks occurred only when the infection produced fever, malaise, cough or coryza. The dominant role of fever in these episodes immediately suggests the profound involvement of adrenergic effector mechanisms. The presence of autoantibodies to beta-adrenoceptors in patients correlated well with a reduced beta—and an increased alpha-adrenergic responsiveness. Virus infections can elicit autoantibody formation.

In patients with atopic dermatitis an increased susceptibility and abnormal host response to viral infections in general. Defective cytotoxic T cells, abnormally functioning macrophages and natural killer cells, a reduced production of IFNα in children, and of IFNγ in atopic patients with food allergy has recently been demonstrated. Lymphocytic cyclic AMP-phosphodiesterase, that destroys cyclic AMP, is increased in atopic dermatitis and in allergic respiratory disease of adults, and this increased activity correlated closely with histamine release from basophils. Peripheral blood leukocytes and lymphocytes in atopic dermatitis have frequently demonstrated impaired beta adrenergic reactivity.

Allergic tissue injury may be initiated by antigen-specific IgE antibodies that combine with Fcε receptors on various cell types and trigger mediator release upon encounter with the antigen. Various noxious agents that are capable of triggering asthma are capable of releasing inflammatory mediators from the same target cells. Accounting only for those pharmacologic mediators where the cell-type has been identified, the spectrum of mediator-storing, synthesizing, or transporting cells includes neutrophil leucocytes, basophilic leucocytes eosinophilic leucocytes; mast cells, “chromaffin-positive” mast cells, enterochromaffin cells, chromaffin cells; platelets, neurosecretory cells and nerve cells that potentially produce all amine-mediators as well as prostaglandins and kinins.

Diet in infancy and bronchial hyperreactivity later in childhood

Sixty-seven atopy-prone children (atopic family group, AFG) and 52 children with no family history of atopy (NAFG) were followed for 10 years. During infancy, the mothers of the newborn AFG children were advised to adjust their infants' diet, with a view toward minimizing the risk of atopy, and not to keep pets. Pulmonary function tests, methacholine inhalation challenge (MIC), and skin prick tests (SPT) were done in order to evaluate the bronchial reactivity and skin reactivity in the two groups. A pathological result in MIC was found in 20 (30%) of the AFG children and in 10 (19%) of the NAFG children. Such results of MIC were more common in the children with positive SPT results than in those without (67% vs. 24%). In regard to the diet consumed in infancy, MIC was pathological in 23% of children with and in 36% without prophylactic diet in infancy. For MIC, using the new, Spira electro 2 dosimeter equipment, the sensitivity was 75% and specificity 97%, but the predictive value for diagnosing bronchial asthma was only 25%. The important advantage of our method is that the degree of bronchial reactivity can be estimated by responses to increasing provocative doses. Our observations confirm that the new method is suitable for detecting bronchial asthma in clinical practice but it seems not to be optimal for epidemiological studies. We concluded that later bronchial hyperreactivity can not be diminished by avoiding home pets or providing a hypoallergenic diet during infancy.

The murine epsilon receptor modulating protein: a novel serine protease which modulates CD23 binding of IgE

In our recent previous studies, we have identified and purified a murine 17-kDa protein which diminishes the avidity of binding between IgE and CD23 (low-affinity Fc receptor for IgE) without decreasing the quantitative expression of the CD23. The protein was thus designated epsilon receptor modulating protein (epsilon RMP). In this study, we have further characterized this protein and have found that (i) epsilon RMP is inactivated by phenylmethylsulfonyl fluoride and decomposes N,alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester, as well as N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide; (ii) epsilon RMP does not work directly on B cells but requires CD4+ T cells to decrease functional expression of CD23 on B cells; and (iii) the partial internal amino acid sequence of epsilon RMP, obtained by using in situ cyanogen bromide cleavage on polyvinylidene difluoride membrane is unique. These data thus clearly demonstrate that epsilon RMP is a novel serine protease controlling the functional expression of CD23 through the participation of CD4+ T cells. Mechanisms of the involvement of CD4+ T cells are discussed.

Purification of murine suppressive factor of allergy into distinct CD23-modulating and IgE-suppressive proteins

The murine suppressive factor of allergy (SFA) has been purified from a T-cell hybridoma and found to consist of two functionally and biochemically distinct protein molecules. One protein (17 kDa) modulates the low-affinity Fc receptor for IgE on lymphocytes (i.e., CD23); it decreases the binding avidity of IgE to CD23-bearing B cells without affecting quantitative expression of CD23 and is thus designated epsilon-receptor-modulating protein. The second protein (30 kDa) suppresses IgE biosynthesis (i.e., SFA). This purified SFA suppresses interleukin 4-induced IgE and IgG1 synthesis by lipopolysaccharide-activated spleen cells but has no effect on other antibody isotypes; since the activity of SFA is not blocked by anti-interferon gamma monoclonal antibody, it is thus distinct from interferon gamma. The data presented indicate that epsilon-receptor-modulating protein and SFA are protein molecules that are involved in modulating the CD23 molecule and IgE antibody synthesis, respectively.

Atopy in children with and without a family history of atopy. II. Skin reactivity

The influence of prolongation of breast feeding and postponement of introduction of solid food during infancy on skin reactivity at the age of five years was studied. At least one positive skin prick test result was observed in 23% of the 70 children with a family history of atopy and in 17% of the 58 children with no such history. Of the 26 skin-test-positive children, 54% exhibited positive reactions to cat dander and 42% to birch pollen. Of the 6 children with asthma, 6 with rhinitis and 17 with eczema, skin reactivity was observed in 66%, 66% and 35%, respectively. Contact with a cat during the first three to four months of life did not correlate with skin test positivity at the age of five years. Skin test positivity to birch pollen was more common in children born in January to February, probably because they were at a vulnerable age in their first birch pollen season in May. No preventive effect by the diet consumed during infancy was seen on subsequent skin test results in relation to common allergens.

The cellular lesion responsible for exaggerated IgE synthesis accompanying allergic breakthrough

Appropriate levels of IgE are maintained by a cellular and molecular network composed of (1) a suppressive, Ly-1+, CD4+ T cell-dependent arm that is activated by inappropriate high levels of IgE and (2) an enhancing, CD8+ T cell-dependent arm that controls this suppression in a feedback regulatory manner. Ly-1+ T cells also function to counterbalance (inhibit) the activity of these latter CD8+ T cells. It has been previously shown that Ly-1+ T cells can reverse low-dose irradiation-induced enhancement of IgE antibody responses (i.e., allergic breakthrough). We have analyzed lymphocytes isolated from mice subjected to low-dose irradiation to determine which component of this network is defective in such animals. Stimulation of normal lymphocytes with IgE in vitro resulted in the release of lymphokines that suppress IgE antibody responses. In contrast, similar stimulation of lymphocytes from irradiated mice did not elicit secretion of such suppressive lymphokines, unless the cells were depleted of CD8+ T cells or reconstituted with normal Ly-1+ T cells. Because Ly-1+ T cells of irradiated mice could not reconstitute the response, we conclude that this functional subset of CD4+ T cells, which normally controls CD8+ T cell activity in this network, is defective in animals that exhibit irradiation-induced allergic breakthrough.

Adoptive immunotherapy with IL-2 results in the loss of delayed-type hypersensitivity responses and the development of immediate hypersensitivity to recall antigens

Skin testing represents a direct method of assessing immune responses in vivo. Twenty-six patients with metastatic cancer of the lung, kidney, or melanoma were treated with adoptive transfers of autologous tumor-infiltrating or blood lymphocytes and continuous infusions of interleukin-2 (IL-2). Prior to therapy, cutaneous anergy to recall antigens was observed in 19 patients (73%), whereas 6 (27%) displayed normal delayed-type hypersensitivity (DTH) responses. When tested again at the end of therapy, DTH responses could not be elicited in any of the patients. Proliferative responses to skin test antigens, lectins, and IL-2 diminished progressively during therapy but returned to baseline values at 1 month. Unexpectedly, 14 of these patients (53%) developed immediate skin test responses to candida antigens and 5 (19%) to mumps antigens. These immediate responses were characterized by local erythema and induration that developed within minutes of injecting antigen. Biopsies displayed marked dermal edema and infiltration by eosinophils. Although serum IgE levels were not increased, immediate reactivity could be transferred by a heat-sensitive serum factor. The implications of this novel response are uncertain, and its development did not correlate directly with the anti-tumor effects of therapy. We conclude that adoptive immunotherapy with IL-2 produces a reduction in cutaneous DTH and diminished responses to mitogens while simultaneously promoting cutaneous allergy. We hypothesize that this may reflect diminished IL-2 production by antigen-specific helper T cells and that other lymphokines may promote these immediate hypersensitivity responses.

Compliance with a dietary manipulation programme in families with infants prone to atopy

The success of familial compliance with a dietary manipulation programme was studied prospectively in 91 newborn babies from atopic families for up to 12 months. The control group consisted of 72 infants from non-atopic families. The percentages of infants breast-fed at the age of six months were 58% and 38% in the study group and control group, respectively. The introduction of cow's milk based formulas was postponed until the age of three months in 63% of the infants in the study group and 47% of the infants in the control group. Solid food was avoided during the first three months in 76% and 45% of the infants in the study group and control group, respectively. Maternal age, smoking and low social class were associated with poor compliance. The existence of atopic dermatitis in any member of the family was associated with good compliance. The main advantages of our programme were the increased number of children breast-fed until the age of six months, and the reduced number of infants introduced to cow's milk based formulas or solid food before three months of age.

Drug-induced skin reactions in patients with acute non-lymphocytic leukaemia

The incidence of drug-induced skin rashes and related factors were analysed in a retrospective study of 151 patients with acute non-lymphocytic leukaemia (ANLL). 91 (60%) developed a drug-related toxicodermia to one or more drugs during remission, induction and maintenance therapy. The incidence of rashes was mainly confined to the blastic stage of leukaemia and occurred significantly less often during remission. Patients with acute myeloid leukaemia, FAB classification M1, M2 and M3 (M1-3) developed skin reactions more often than those of types M4 and M5 (M4-5). Women suffered more frequently from drug-induced skin lesions than men. The incidence of drug-associated rashes was significantly higher in patients with ANLL than in the general population for: Allopurinol (16%), co-trimoxazole (14%), miconazole (28%), and ketoconazole (18%). The incidence for the penicillins (12%) and cephalosporins (3%) conformed to the upper limit as reported for the general population. Additional toxic effects of combined therapy could not explain the differences observed and a dearrangement of the immunesystem during the blastic stage of leukaemia is suggested.

IgE synthesis in vitro: attempt to isolate stimulating factors

Studies made in our laboratory have demonstrated the presence in atopic serum of enhancing factors(s) for in vitro IgE synthesis by peripheral blood lymphocytes (BPL). Here we show that these enhancing factors can be recovered from human serum by means of immunoabsorbents. This factor is able to stimulate in vitro IgE synthesis by PBL independent of presence of IgE.

The Epstein-Barr virus-induced production of IgE by human B cells

B cells, isolated from the blood of healthy individuals and patients allergic to pollen, produced IgE when exposed to the human B-cell polyclonal activator, Epstein-Barr virus (EBV) in vitro and placed in culture. Secreted IgM and IgE were measured using immunoenzymatic assays. No difference was seen between healthy donors and allergic patients in the amount of IgE (or IgM) secreted. Cells were placed in limiting dilution cultures in order to determine the frequency of cells producing IgE or IgM (total and pollen specific) on exposure to EBV. Again, no significant differences in EBV-driven, B-cell precursor frequencies (PF) were seen between normal and allergic individuals. EBV-driven B-cell PF for total IgM and IgE, and pollen-specific IgM and IgE secretion, were 1/450, 1/6500, 1/83,000, and less than 1 per 2,500,000, respectively, for cells from healthy donors, and 1/140, 1/4000, 1/56,000 and less than or equal to 1 per 2,000,000, respectively, for cells from allergic patients. We propose that the increased IgE levels seen in atopic individuals result solely from regulatory defects, rather than an increase in the frequency of B cells committed to the secretion of IgE.

The induction and kinetics of an anti-DNP IgE response in dogs

Twenty-eight dogs immunized to dinitrophenol-ascaris (DNP-ASC) at birth and then three times at two week intervals produced serum anti-DNP antibody. The IgM response was detected one week after primary immunization and lasted for up to five weeks. The IgE and IgG antibody response in general was not present until week three but persisted through the immunization schedule. Although variation in the level and duration of the antibody response was detected between individual dogs, each dog did have a response that included all three isotypes examined.

Correction of an in vitro immunoregulatory defect in atopic subjects by the immunostimulating drug fanetizole mesylate (CP-48,810)

The effect of Fanetizole mesylate or CP-48,810, a new immunostimulating drug, on suppressor cell function and IgE synthesis in vitro was evaluated in atopic patients with allergic rhinitis and/or asthma and eczema. In the absence of the drug, histamine (10(-3)M) stimulated blood mononuclear cells from 23 atopic patients suppressed concanavalin A-induced lymphocyte proliferation by a mean (+/- S.E.M.) of 9.3% +/- 3.5 (compared to 25.1% +/- 2.7 for histamine stimulated mononuclear cells from non-atopic controls). The addition of the drug (2.5 X 10(-4)M) in vitro significantly increased histamine suppressor cell activity of atopic patients to 26.6% +/- 3.9 (compared to 24.7% +/- 2.8 for control cells in the presence of the drug). In order to determine a possible mechanism through which CP-48,810 might enhance histamine-induced suppressor activity, we examined the effects of the drug on the production of histamine-induced suppressor factor (HSF) by lymphocytes and the production of prostaglandin E2 by blood monocytes in the presence of HSF. Supernatants generated from histamine (10(-4)M) stimulated patient lymphocytes caused a 9.0% +/- 1.8 suppression of concanavalin A-induced lymphocyte proliferation (compared to 25.0% +/- 3.1 caused by supernatants from normal subjects). If the drug (2.5 X 10(-4)M) was added at the beginning of culture, HSF activity in supernatants derived from atopic lymphocytes increased significantly to 20.2% +/- 1.8 (compared to 23.3% +/- 3.9 for drug treated control supernatants). Prostaglandin E2 production by atopic monocytes exposed to HSF was less than that of normal monocytes in the absence of the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of antigen structure in the regulation of IgE isotype expression

Tobacco glycoprotein (TGP) is a glycoprotein containing rutin-like polyphenol groups that is purified from cured tobacco leaves and can be detected in condensates of tobacco smoke. One-third of normal humans have been shown to manifest immediate, IgE-mediated, wheal and flare reactions to an intradermal injection of TGP. Rutin-like moieties are also found in a wide variety of vegetable foods. The possible importance of sensitivity to TGP in the pathogenesis of the vascular and pulmonary complications of tobacco smoking has stimulated us to study the immune response of mice to TGP and the role of rutin groups in influencing isotype expression. A series of three intradermal injections of TGP elicits a long-lasting IgE antibody response in mice. However, no hemagglutinating antibodies are produced. Similarly, immunization with a rutin derivative of bovine serum albumin stimulates IgE antibodies to bovine serum albumin but little hemagglutinating antibodies. In contrast, mice injected in the same manner with bovine serum albumin produce both IgE and hemagglutinating antibodies. Thus, the rutin moiety is implicated as exerting a regulatory effect on isotype expression by suppressing the production of serum antibodies of isotypes other than IgE. The immunization procedure employed (which involves an initial injection of 100 micrograms of antigen in phosphate-buffered saline, followed, at monthly intervals, by two intradermal injections of 100 micrograms of antigen precipitated on alum) apparently fails to stimulate the normal "down-regulation" of the IgE response so that a persisting high-titered response is obtained.

A rapid screening assay for detection of IgE-binding factors in humans

During the last few years studies in rats and mice have demonstrated IgE-binding factors, some of which have IgE-selective regulatory activities. This prompted us to develop a rapid, sensitive screening assay for measuring IgE-binding factors in humans. The principle of the assay is to measure the degree of inhibition of binding between anti-human IgE antibodies and human IgE. Thus, 200 pg IgE plus testing samples were added to each well precoated with anti-human IgE antiserum. After an overnight incubation, the wells were washed and radiolabeled anti-IgE antibodies were added to the wells. Under the optimum conditions, the assay can detect 10(-11)M anti-human IgE antibodies. With this assay, we have been able to detect IgE-binding factors in the supernatants of 2 human B cell lines which bear Fc receptors for IgE (FcR epsilon) on their surface membranes (e.g., WIL-2 and RPMI 8866), but not in the supernatants of DAUDI cells (a human cell line without FcR epsilon). Furthermore, the IgE-binding factors of WIL-2 cells were specifically adsorbed to, and eluted from, IgE-coupled Sepharose, but not BSA-Sepharose. These findings prove that the inhibition factors are indeed human IgE-binding factors, and that the assay described herein is a specific and sensitive screening assay for detecting human IgE-binding factors.

Modulating effects of enzymes on T gamma and T mu cells in patients with atopic dermatitis

Ten patients with moderate to severe atopic dermatitis had increased levels of IgE in the blood and a reduced level of T cells with Fc receptors for IgG (T gamma). After pronase and trypsin digestion of Fc receptors, cultured T cells regenerated the Fc receptors, but preserved the difference between patients and controls. Neuraminidase treatment increased the T gamma-cell level in both patients and controls. Serum from patients with atopic dermatitis could not reduce the T gamma-cell expression in the controls. With regard to Fc receptors, no qualitative difference was observed between patients and controls, but a genuine quantitative difference accounts for the observed reduction of T gamma cells in blood.

Abnormal histamine-induced suppressor-cell function in atopic subjects

To detect a potential defect in immunoregulatory function in atopic subjects, we studied histamine-induced suppressor-T-cell activity and histamine Type 1 and Type 2 receptors on T cells. Peripheral-blood mononuclear cells from 16 atopic subjects generated less histamine-induced suppressor activity than did those from 20 nonatopic normal controls (P less than 0.005). The percentage of T lymphocytes bearing histamine Type 2 receptors was lower in the atopic group than in the control group (P less than 0.001), but the percentage of cells with Type 1 receptors was the same in both groups. In the atopic subjects, the functional suppressor-cell abnormality positively correlated with the decreased phenotypic expression of histamine Type 2 receptors. No abnormality in concanavalin A-induced suppressor activity was detected in these subjects. Nonatopic control subjects with systemic mastocytosis had normal functional and phenotypic data, suggesting that chronic activation of atopic T cells in vivo by circulating histamine does not explain the abnormal histamine-induced suppressor response.

Antigen-induced bronchial anaphylaxis in actively sensitized SD rats. Effects of immunization and provocation doses of antigen and of pretreatment with DSCG, theophylline, terbutaline and a new anti-allergic xanthine derivative, D4026

Bronchial anaphylactic reactions, estimated as increase in intratracheal pressure, were precipitated by intravenous injections of antigen into actively sensitized SD rats. The degree of bronchial reactivity was found to depend on both the challenge dose and the immunization dose of antigen; therefore the course of the capacity to respond was recorded as a function of these variables. The degree of the bronchial anaphylactic response could be reduced by pretreatment with disodium cromoglycate, terbutaline or a new anti-allergic xanthine derivative, D 4026, in some groups of animals. The efficacy of each agent was found to depend on the dose of antigen used for sensitization and for provocation of the bronchial reaction rather than on the strength of the response. Taken together, the data suggest that more than one type of homocytotropic antibody mediates bronchial anaphylactic reactivity in the SD rat.

Stimulation of primary in vitro IgE antibody responses in culture of human peripheral mononuclear cells

Experiments are presented herein that demonstrate the capacity to stimulate human peripheral mononuclear cells to synthesize and secrete significant quantities of IgE molecules in vitro by exposure to appropriate concentrations of 2,4-dinitrophenyl (DNP)-protein conjugates, pokeweed mitogen (PWM), or a combination of DNP-proteins and PWM. Cultures stimulated in this fashion synthesize increased quantities of both total IgE and DNP-specific IgE antibody molecules. This in vitro human IgE antibody system should provide a useful tool for further exploration of regulatory control of IgE responses in both normal humans and those manifesting various forms of IgE-mediated allergic disorders.

New concepts concerning the clinical control of IgE synthesis

Prospects for new therapeutic approaches to IgE-mediated allergic diseases have arisen from (1) recent experimental observations that have suggested new concepts concerning the pathogenesis of the allergic phenotype, and (2) adaptation of previously described methods for induction of specific immunological tolerance to problems to allergy. The bases for these new approaches to allergic diseases are summarized herein.

Regulation of IgE antibody production by serum molecules. VI: Preliminary biochemical and immunological characterization of serum molecules active in suppressing IgE antibody production

Molecules present in the serum and ascites fluids of low IgE responder mice previously inoculated with complete Freund's adjuvant have been analyzed in terms of certain biochemical and immunological characteristics. These studies demonstrate that the active molecules, termed "suppressive factors of allergy" (SFA), are (1) nondialyzable, (2) not associated with low-density or high-density lipoproteins, (3) heat stable, (4) precipitable by ammonium sulfate, and (5) approximately 150,000 daltons in molecular size. Studies with immunoadsorbents prepared from various antisera indicate that the suppressive molecules are (1) not immunoglobulin in nature, (2) not reactive with specific anti-H-2 alloantibodies, but (3) reactive with anti-beta 2m antibodies as well as (4) heterologous antisera raised against CFA-immune mouse serum.

Regulation of IgE antibody production by serum molecules. III. Induction of suppressive activity by allogeneic lymphoid cell interactions and suppression of IgE synthesis by the allogeneic effect

Antibody responses of the IgE class are, like other immunoglobulin classes, regulated by a finely-tuned network of complex cellular and molecular interactions (1). Previous studies conducted in our laboratory (2, 3) have provided new insights into the differences in control mechanisms that result in individuals manifesting either the high (allergic) or low (nonallergic) IgE responder phenotype. These experiments have shown that certain manipulations (i.e. low dose X-irradiation) convert normally low responder mice to high IgE responders, apparently by diminishing a suppressor T-cell mechanism which normally dampens, rather selectively, IgE antibody production in such individuals. Similar findings have been made by Watanabe et al. (4). Recently, we have been studying the types of manipulations that could reverse the high IgE responsive state back to a low one. These studies (2, 3, 5, 6) have demonstrated that the high IgE responses induced in low responder mice can be substantially diminished, and even abolished, by passively transfusing serum or ascetic fluid from donor mice previously inoculated with mycobacterial-containing complete Freund's adjuvant (CFA). Because the suppressive activity of CFA-immune serum or ascitic fluid is so highly selective for IgE antibody production, we have recently termed these serum substances suppressive factors of allergy (SFA) (2, 3). The present study was undertaken to determine whether alternative means, particularly those that avoid administration of CFA, could be devised for the induction of SFA. Herein, we report the effectiveness of allogeneic lymphoid cell interactions in inducing SFA, both in vivo and in vitro, as well as the potent suppressive effects of an in vivo allogeneic effect on irradiation enhanced IgE antibody production in low responder mice.

An in vivo model for assessing effects of drugs and toxicants on immunocompetence

An in vivo assessment of the capacity of exposed animals to respond to antigenic challenge is recommended as the first screening phase for detecting potential immunotoxicants, with subsequent in vitro functional tests utilized to pinpoint the site of induced cellular alteration. Risk assessment of a candidate toxicant is based on a comparison of immune profiles of exposed animals with those of animals treated with prototype immunotoxicants. Extrapolation to man is facilitated by the use of licensed vaccines for antigenic challenge and the selection of clinically useful pharmaceutical drugs as prototype immunotoxicants. Three chemically induced alterations in immune responses are presented: 1) Immunosuppression characterized by impaired capacity to produce IgG and IgM classes of antibody on stimulation, 2) chronic high levels of IgE antibody in response to commonly encountered antigens, 3) modification of the capacity to mount an inflammatory response to antigenic material.