Semi-purification of the immunoglobulin E-sweat antigen acting on mast cells and basophils in atopic dermatitis

BACKGROUND: Sweating aggravates the symptoms of atopic dermatitis (AD). We have recently reported positive skin reactions and histamine release from basophils in response to autologous sweat in patients with AD. OBJECTIVE: To characterize the biochemical and immunological properties of the substance in sweat that evokes histamine release and to study the usability of the basophil-histamine release test with the sweat antigen for AD. METHODS: Sweat collected from healthy volunteers was purified using chromatographies. Serum immunoglobulin (Ig)E of four patients with AD were purified using an affinity-chromatography column with anti-IgE antibodies. The amount of semi-purified sweat antigen (138 ng protein/ml) that induced a half-maximum reaction of basophils of a patient with AD was utilized for the basophil histamine release test. The involvement of specific IgE and high-affinity IgE receptor (FcepsilonRI) in the reactions was examined using basophils of healthy volunteers, a human mast cell line (LAD2), and a rat basophilic leukemia cell line transfected with human alpha-subunit of FcepsilonRI (RBL-48). RESULTS: The semi-purified sweat antigen induced histamine release from the basophils of 47 of 61 (74.6%) patients with AD and four of 46 (8.7%) healthy controls. Both basophils and mast cells sensitized with the patient-derived IgE showed degranulation upon stimulation with the sweat antigen. However, no reaction was observed when cells were sensitized with myeloma IgE or the antigen was treated with proteases. CONCLUSION: The semi-purified standardized sweat antigen consists of a protein that induces degranulation of basophils and mast cells via antigen-specific IgE and FcepsilonRI in patients with AD.     

Sweat antigen induces histamine release from basophils of patients with cholinergic urticaria associated with atopic diathesis

Background  We previously demonstrated that the semipurified human sweat antigen causes skin reactions and histamine release from basophils via specific IgE in patients with atopic dermatitis (AD). Patients with cholinergic urticaria (ChU) also develop skin reactions and histamine release of basophils in response to autologous sweat.
Objectives  To study whether or not patients with ChU share sensitivity for the sweat antigen with patients with AD and to study the clinical characteristics among patients with ChU and the relationship with histamine-release activity of basophils.
Methods  The sweat antigen that induces histamine release from basophils of patients with AD was prepared by Con-A, anion-exchange and reverse-phase chromatography. Relationships between histamine-release activity against the sweat antigen and clinical features of patients with ChU were analysed.
Results  Twenty-three of 35 patients with ChU showed > 5% net histamine release in response to the semipurified sweat antigen, whereas none of healthy controls did so. In patients with ChU, histamine release in response to semipurified sweat antigen significantly correlated with the level of serum IgE and eosinophil numbers in peripheral blood. Incidence of each atopic disease in patients with ChU tended to be higher than in the general Japanese population. When the patients were categorized according to their responses in the histamine release test, the positive group tended to show a higher incidence of AD and bronchial asthma compared with the negative group.
Conclusions  ChU and AD may share hypersensitivity to common antigens in sweat. The sweat allergy and atopic diathesis are associated with each other.     

Histamine release-neutralization assay for sera of patients with atopic dermatitis and/or cholinergic urticaria is useful to screen type I hypersensitivity against sweat antigens

We previously reported that about 80?% of patients with atopic dermatitis and 60?% with cholinergic urticaria revealed type I allergy against sweat, by means of skin test against autologous sweat and/or histamine-release test for peripheral blood basophils with semi-purified sweat antigen. In this study, we developed an assay for sera to neutralize histamine-releasing activity of semi-purified sweat antigen. The semi-purified sweat antigen was pre-incubated with serially diluted sera for 30?min at 37?°C and was subjected to histamine-release activity. Histamine release-neutralization (HRN) activities were calculated by measuring the amount of histamine release from basophils in the presence or absence of semi-purified sweat antigen. Of 62 subjects, 39 showed positive histamine release (≥5?%) from their basophils in response to semi-purified sweat antigen, and sera of 34 out of 39 subjects (87.2?%) were also positive in HRN activity (≥10?%). The specificity of the HRN assay was 0.522. Moreover, HRN activities in sera were largely correlated with degrees of histamine release from peripheral blood basophils of the same donors in response to sweat antigen. To identify the substance that neutralizes histamine-release activity, we removed IgE and IgG from the sera of HRN (+) subjects by column chromatography. The HRN activities in 30 out of 42 sera were largely reduced by the removal of IgG. On the other hand, sera of four subjects lost HRN activity by the removal of IgE, suggesting that the majority of HRN (+) subjects have serum IgG against the sweat antigen as well as IgE bound to peripheral basophils. Thus, the HRN assay maybe useful for the screening of type I allergy against sweat antigen.     

IgG anti-IgE from atopic dermatitis induces mediator release from basophils and mast cells

IgG antibodies containing anti-IgE activity isolated from a patient with atopic dermatitis (H-aIgE) induced mediator release from human basophils and mast cells isolated from skin and lung tissues. The release of histamine was calcium- and temperature-dependent and did not involve cytotoxicity. There was an excellent correlation (r = 0.88; p less than 0.001) between the maximum percent histamine release from human basophils induced by rabbit anti-IgE (R-aIgE) and H-aIgE. H-aIgE was approximately 30 times more potent than R-aIgE in inducing mediator release from human basophils, skin, and lung mast cells. H-aIgE specifically desensitized human basophils to a subsequent challenge with both H-aIgE and R-aIgE. Lactic acid removal of IgE from human basophils blocked the releasing activity of both R-aIgE and H-aIgE. Passive sensitization with hyperimmune sera or purified IgE myeloma restored the response of basophils to both R-aIgE and H-aIgE. IgE purified from three different myeloma patients concentration-dependently blocked the histamine releasing activity of both R-aIgE and H-aIgE.     

In vitro effects of ultraviolet A on histamine release from human basophils

BACKGROUND: As long-wave ultraviolet (UV) radiation penetrates the dermis, connective tissue cellular components and circulating blood cells can be possible targets for solar UVA. Basophils, involved in the effector phase of the inflammatory response, play a part in skin diseases such as chronic urticaria, psoriasis, atopic dermatitis, fixed drug eruption, allergic contact dermatitis, urticaria pigmentosa, systemic sclerosis and bullous pemphigoid. OBJECTIVE: The evaluation of the in vitro effect of UVA on histamine release from human basophils. METHODS: Basophils from healthy human volunteers were irradiated, respectively, with UVA at doses of 2.5, 5, 7.5, 10, 20 and 50 J/cm2 and then incubated with an anti-IgE serum. A fluorimetric technique was employed to determine histamine release from samples: (i) incubated with 2% HClO4 (complete lysis of basophils); (ii) irradiated with increasing doses of UVA; and (iii) unirradiated (controls). RESULTS: Histamine release was: 100% for HClO4 incubated basophils, 30% for unirradiated and anti-IgE incubated cells (controls) and 27%, 24%, 34%, 41%, 60% and 70% for basophils irradiated with UVA doses, respectively, of 2.5, 5, 7.5, 10, 20 and 50 J/cm2 and incubated with anti-IgE. Histamine releasability from irradiated samples was statistically significant (P < 0.05), in comparison with controls, at UVA doses equal to 5, 10, 20 and 50 J/cm2. CONCLUSIONS: UVA exerts, at least in vitro, a biphasic dose-dependent action on histamine release from human basophils incubated with an anti-IgE serum: at the lowest irradiation doses (< 5 J/cm2) it exerts an inhibitory effect and at the highest doses (> or = 10 J/cm2) histamine release increases significantly.     

Human basophil releasability. II. Changes in basophil releasability in patients with atopic dermatitis

"Releasability" is the theory whereby biochemical events in basophils influence the capacity to release chemical mediators in response to activating stimuli. We have compared the releasability of basophils from 21 young patients with atopic dermatitis (AD) with that from 17 normal donors of matched ages. Basophils were challenged with several different stimuli: rabbit antihuman Fc epsilon (anti-IgE), N-formyl-methionyl-leucyl-phenylalanine (f-met-peptide), Ca++ ionophore A23187, and D2O. Basophils from patients with AD released significantly more histamine both "spontaneously" and in response to D2O than did controls. The basophils of patients with AD were significantly more responsive to anti-IgE and to A23187. There was no difference between the percent f-met-peptide-induced histamine release in patients with AD vs controls. No significant correlation between percent histamine release with optimal or suboptimal concentrations of the stimuli and serum IgE level was found. There was a significant correlation between the sensitivity of the cells to release with f-met-peptide and the response to A23187 both in control and in AD patients. Since basophils are thought to play some role at the site of inflammation in AD, their increased releasability might contribute to the symptoms of these patients.     

Staphylococcus aureus enterotoxins induce histamine and leukotriene release in patients with atopic eczema

BACKGROUND: Chronic skin colonization with Staphylococcus aureus is a characteristic feature of atopic eczema (AE), and about 60% of S. aureus strains isolated from the skin of patients with AE secrete enterotoxins. Furthermore, IgE antibodies to S. aureus enterotoxins have been identified in 78% of patients with AE. OBJECTIVES: To examine the S. aureus enterotoxin-induced histamine and leukotriene release of basophils from patients with AE. METHODS: Peripheral blood basophils from patients with AE were stimulated with the staphylococcal enterotoxins A, B, D, E and toxic shock syndrome toxin-1. Additionally, priming experiments were performed with interleukin (IL)-3, IL-8 and granulocyte/macrophage colony-stimulating factor followed by stimulation with S. aureus enterotoxins. RESULTS: In patients with AE, basophils secreted significantly higher amounts of histamine and leukotriene C4 (LTC4) than in healthy controls. The priming experiments showed additional histamine and LTC4 release in the group of AE patients. CONCLUSIONS: Histamine and leukotriene generation from atopic basophils stimulated with staphylococcal enterotoxins may indicate a role for these toxins as possible allergens in at least a subgroup of patients with AE.     

The sweat of patients with atopic dermatitis contains specific IgE antibodies to inhalant allergens

We have investigated levels of total and specific against inhalant allergens in the sweat of 15 patients with atopic dermatitis, 10 patients with allergic rhinitis and high levels of specific IgE in the serum, and five patients with psoriasis without atopy as controls, by means of various commercial methods such as fluorescence immunoassay, nephetometry, chemiluminescence assay, enzyme immunoassay and the radioallergosorbent lest. Total IgE and specific IgE antibodies were detectable in the sweat of patients with atopic dermatitis as well as of patients with allergic rhinitis alone. These levels of total IgE in the sweat correlated with the severity of the skin disease (P < 0·05). By means of the Ciba Corning assay (P < 0·001), the fluorescence immunoassay (P < 0·05) and the nephelometry assay (P < 0·05), positive correlations were then established between the levels of total IgE in the serum and the sweat. Moreover, specific IgE antibodies to birch pollen and Dermatophagoides pteronyssinus were detectable in the sweat and correlated positively with these specific IgE levels in the serum (P < 0·05). Further, the specific IgE levels against these allergens in the sweat also correlated with the severity of dermatitis (P < 0·05). It is suggested that these specific IgE antibodies against certain inhalant allergens in the sweat of patients with atopic dermatitis may play a role in allergen trapping in the skin.     

An in vitro study of IgE production in severe atopic dermatitis.

Peripheral blood lymphocytes from 4 patients with severe atopic dermatitis and with high serum IgE levels produced measurable amounts of IgE in vitro in repeated tests. These patients had increased numbers of IgE-bearing peripheral blood lymphocytes on at least one test occasion. No measurable IgE production in vitro was found in 6 other patients with atopic dermatitis and in 3 healthy controls. Inhibition of the IgE production was observed following treatment with PHA, Con A, PWM, mixed lymphocyte culture and radiation. LPS and histamine induced neither definite stimulation nor inhibition of IgE production. Supernatants from Con A stimulated cells were used in tests for suppressor factors. The hypothesis that depressed suppressor function of the T cells might be responsible for the tendency to increased IgE production in atopic dermatitis is discussed.     

Decreased release of lysosomal enzymes from peripheral leukocytes of patients with atopic dermatitis

Peripheral blood leukocytes from fifteen patients with atopic dermatitis and ten normal nonatopic volunteers were incubated with various stimuli in vitro, and the release of the lysosomal beta-glucuronidase into the supernatant was measured. beta-Glucuronidase release was significantly reduced in patients with severe atopic dermatitis after stimulation with aggregated IgG, horse antihuman lymphocyte globulin (ALG), zymosan, and yeast-activated serum. There was an indirect correlation (r = -0.83) between aggregated IgG-induced beta-glucuronidase release and the intensity of clinical symptoms; however, there was no correlation with serum IgE levels. The enzyme release measured was not caused by cellular lysis, except for high concentrations of antilymphocyte globulin, as determined by lactic dehydrogenase (LDH) activity in the supernatant. It is concluded that lysosomal enzyme release defects might be involved in the well-known decreased resistance to infections in patients with atopic dermatitis.     

Interleukin-1 release from peripheral blood monocytes and soluble interleukin-2 and CD8 receptors in serum from patients with atopic dermatitis

In 31 adult patients with atopic dermatitis, the capacity to secrete interleukin-1 (IL-1) from peripheral blood mononuclear cells and from purified monocytes was investigated following stimulation with lipopolysaccharide. We also measured soluble interleukin-2 receptor levels (sIL-2R) and CD-8 receptor in serum from some of the patients in order to estimate the degree of lymphocyte stimulation in vivo. We observed that purified monocytes from patients with atopic dermatitis released more IL-1 than unseparated blood mononuclear cells did and also had significantly greater IL-1 activity than non-atopic donors. Addition of histamine in concentrations of 10(-7) to 10(-4) M did not suppress, but rather augmented the IL-1 activity release. An increased monocyte-IL-1 release could lead to increased T lymphocyte activity. We observed that 60% of the patients had increased sIL-2R concentrations in serum. There was no correlation between serum IgE and sIL-2R. Our observations indicate that monocytes in atopic dermatitis patients release increased quantities of IL-1, supporting an augmented T lymphocyte activation in the patients.     

Disordered cyclic nucleotide metabolism--a basic defect in atopic dermatitis

Dysfunction in a wide variety of cellular immune mechanisms occurs in atopic dermatitis and contributes to the clinical presentation of the condition. The increased incidence of cutaneous viral and fungal infections, observed clinically in atopic dermatitis, suggests altered T-lymphocyte function and elevated serum IgE levels suggest deregulation of B-lymphocyte function. The clinical features of pruritus and erythema raise the possibility of increased release of inflammatory mediators into the circulation. In vitro studies have confirmed abnormalities in T-lymphocyte subset numbers and function as well as increased releasability of histamine from blood basophils in atopic dermatitis. Recent studies have revealed abnormalities in the metabolism of cyclic AMP, an important mediator in cellular regulatory mechanisms, in atopic dermatitis. Leucocyte cyclic AMP responses to a variety of agonists are blunted in atopic dermatitis and are due, at least in part, to increased cyclic AMP phosphodiesterase activity. It is unclear at present whether this enzyme abnormality is genetically determined or whether it is induced by increased circulating levels of inflammatory mediators. A number of the in vitro abnormalities in atopic dermatitis appear to correlate with the increase in phosphodiesterase activity. Further research aimed at finding ways to inhibit phosphodiesterase activity in atopic dermatitis and consequently reversing other abnormalities in cellular function, will hopefully open up new avenues of therapy for this common and disabling condition.     

Basophil CD63 expression assay on highly sensitized atopic donor leucocytes-a useful method in chronic autoimmune urticaria

BACKGROUND: The autoimmune subclass of chronic idiopathic urticaria (CU) has been characterized by the occurrence of biologically relevant IgG antibodies against the IgE molecule or the alpha chain of the high-affinity Fcepsilon receptor (FcepsilonRIalpha) on basophils and mast cells. These antibodies are usually detected by autologous serum skin testing and confirmed by histamine release studies, immunoblotting, or enzyme-linked immunosorbent assay, but not always. OBJECTIVES: To detect autoantibodies to the FcepsilonRIalpha in sera of CU patients by a modified serum-induced basophil activation test measured by flow cytometry (FCM) and to evaluate the relationship between the in vitro functional test, the autologous serum skin test (ASST), and the serum levels of IgE, eosinophil cationic protein (ECP) and antithyroid antibodies. METHODS: Sera of 30 patients with CU and 26 patients with systemic autoimmune diseases (systemic lupus erythematosus, dermatomyositis) were tested for CD63 activation marker expression on basophils by FCM. Leucocytes from two highly sensitized atopic donors (D(A1,) D(A2)) and one non-atopic donor (D(NA)) were incubated with patients' sera and double-labelled with anti-IgE and anti-CD63 antibodies. Subsequently, the percentage of CD63-expressing basophils was determined by using FCM. In all CU patients an ASST was carried out and the serum IgE, and ECP levels and antithyroid antibodies were evaluated. RESULTS: Twelve patients had a positive ASST and 14 patients a positive CD63 expression assay. There was a strong correlation between the ASST and CD63 assay. Sera from patients with systemic autoimmune diseases did not raise positive CD63 expression on basophils. There was a moderate negative correlation between the occurrence of atopic serum markers (IgE, ECP) and the ability of sera to induce CD63 expression on basophil cells of D(A2) (P < 0.05). The female sex was preponderant and antithyroid antibodies were more frequent. CONCLUSIONS: Our new technical observation demonstrates that basophils of highly sensitized atopic donors can be successfully used without priming with IL-3 for the in-vitro flow cytofluorimetric diagnosis of CU. With this investigation the characterization of the autoimmune origin of CU is based on an objective in vitro technique.     

Production of interleukin-2 by mononuclear cells in vitro in patients with atopic dermatitis and psoriasis. Comparison with serum interleukin-2 receptor levels.

Atopic dermatitis is associated with profound immunological alterations, in particular decreased lymphoproliferative responses upon stimulation with T-cell mitogens. T-cell blastogenesis involves the production of the soluble cytokine interleukin-2 (IL-2), which in turn upregulates the expression of its own receptor. To investigate the potential role of this cytokine for the pathomechanisms present in atopic dermatitis, 24-h supernatants of PHA-stimulated peripheral blood mononuclear cells from patients with atopic dermatitis (n = 30) of a moderate to severe disease activity were tested for IL-2 activity. In addition, serum concentrations of soluble interleukin-2 receptor (IL-2R) were measured. Non-atopic healthy controls (n = 19) and patients with psoriasis (n = 20), an inflammatory skin disorder with distinct pathogenesis, served as controls. In comparison with psoriasis patients and normal controls, PHA-stimulated mononuclear cells of atopic dermatitis patients released significantly less IL-2 into supernatants. Moreover, there was an inverse correlation between IL-2 concentrations and body surface involvement or serum IgE levels. In contrast, serum IL-2R levels were significantly elevated in both atopic dermatitis and psoriasis, as compared with healthy controls. Furthermore, IL-2R levels in atopic dermatitis patients showed a significant correlation with IgE levels and body surface involvement. The data indicate that T cell activation may occur in both skin diseases. Atopic dermatitis, however, is further characterized by the decreased capacity of mononuclear cells to release IL-2 upon stimulation in vitro.     

IgG4 antibodies in patients with atopic dermatitis

The role of IgG4 in atopic dermatitis was investigated by determining the total amounts of IgG4 and of IgG4 specific for ovalbumin (a food allergen), Dermatophagoides farinae mite antigen and house dust (inhalant allergens) and Candida. These were related to the amounts of total and antigen specific IgE in patients with atopic dermatitis and normal healthy controls. Most patients with atopic dermatitis had greater amounts of total IgG4 and of antigen-specific IgG4 than did normal control individuals. Patients who had received hyposensitization treatment injections had greater amounts of IgG4 than the atopic dermatitis patients not so treated. In patients treated by hyposensitization there was a large increase in the amount of blocking antibody detected by incubating the antigen with the serum overnight before injecting the mixture into the skin of a patient sensitive to the antigen. Blocking activity was also examined by partial inhibition by the serum of IgE-mediated mast cell degranulation and by injection of serum into the skin of sensitive patients before challenge with antigens. In all tests the blocking activity of the serum was related to the amount of antigen-specific IgG4 but not related to total IgG4. In patients with atopic dermatitis who were sensitive to mite antigen, severe cases had small amounts of specific IgG4 and large amounts of specific IgE but in mild cases there was an opposite trend with relatively large amounts of specific IgG4. Large amounts of IgG4 ovalbumin specific antibody were found in children and adults with atopic dermatitis and egg allergy but small amounts of IgE. In infants most of the anti-ovalbumin antibody was IgE with little or no IgG4. The work of others has confirmed that increased amounts of total and antigen-specific IgG4 occur in atopic dermatitis, and it is concluded that IgG4 is a blocking antibody for anaphylactic sensitization responses.     

IgE antibodies to Pityrosporum ovale in atopic dermatitis

An enzyme-linked immunosorbent assay (ELISA) was developed to assess serum IgE antibodies directed against Pityrosporum ovale in patients with atopic dermatitis (AD), atopic patients with allergic respiratory disease (ARD: rhinitis or asthma) but without eczema, and in healthy controls. IgE binding to P. ovale extract was demonstrated in 49% (35/72) of AD patients. In contrast, anti-P. ovale IgE was found in only one of 27 atopic controls without eczema; all healthy control sera (n = 17) were negative. Of 37 AD patients tested intracutaneously with P. ovale, 31 showed immediate-type reactivity, and 20 of these 31 patients had anti-P. ovale IgE detectable by ELISA, while sera from the six non-responders were all negative. Levels of anti-P. ovale IgE were highest in AD patients aged 20-30 years. No correlation was found with the severity of AD, but there was a non-significant tendency (P = 0.06) to higher levels in AD patients with concomittant respiratory allergy. Anti-P. ovale IgE was significantly correlated with total serum IgE, with specific IgE against various aeroallergens as measured by RAST, and with levels of anti-Candida albicans IgE, measured with a similar ELISA. Thus, production of IgE antibodies against P. ovale occurs very frequently in AD, and rarely in patients with atopic disease without skin involvement.     

Dichotomic nature of atopic dermatitis reflected by combined analysis of monocyte immunophenotyping and single nucleotide polymorphisms of the interleukin-4/interleukin-13 receptor gene: the dichotomy of extrinsic and intrinsic atopic dermatitis

Patients with atopic dermatitis display substantial immunologic abnormalities, among which elevated total IgE is considered as a hallmark; however, a subgroup of atopic dermatitis patients exhibits normal IgE levels, but mechanisms contributing to the so-called "intrinsic" or "nonallergic" form of atopic dermatitis are obscure. In order to unravel similarities and differences of both atopic dermatitis subtypes, the phenotype of monocytes, total serum IgE levels, and serum levels of cytokines regulating the IgE production from nonatopic individuals and patients with allergic rhinitis, and extrinsic and intrinsic atopic dermatitis were measured. Concomitantly, genomic DNA probes of all subjects were analyzed for single nucleotide polymorphisms of candidate genes of structures involved in the regulation of the IgE synthesis, such as interleukin-4 and the interleukin-4R/interleukin-13R. Our data show that the surface expression of the high- and low-affinity receptor for IgE (FcepsilonRI and FcepsilonRII/CD23) and the interleukin-4Ralpha chain were significantly elevated in monocytes from patients with extrinsic atopic dermatitis. Furthermore, serum levels of interleukin-13 were significantly increased in patients with intrinsic atopic dermatitis. In addition, the frequency of the interleukin-4Ralpha polymorphism C3223T and the interleukin-4 polymorphism C590T tended to be higher in extrinsic atopic dermatitis than in intrinsic atopic dermatitis. Altogether our findings indicate that intrinsic atopic dermatitis patients exhibit phenotypic and immunologic features, which differ from those of patients with extrinsic atopic dermatitis or other atopic disorders.     

Cutaneous histamine levels and histamine releasability from the skin in atopic dermatitis and hyper-IgE-syndrome

We determined the histamine content in the skin of 22 adults with atopic dermatitis, one patient with hyper-IgE-syndrome, and 20 controls by the enzymatic double isotope assay. In addition, we performed a pilot study of histamine degradation in the skin. We tested, furthermore, the releasability of histamine from skin sections of patients with atopic dermatitis and healthy controls upon challenge with acetylcholine, anti-IgE, and compound 48/80. Histamine was also determined in 13 plasma specimens and was always less than 1 ng/ml. The mean +/- SEM histamine concentration in the skin was 196 +/- 30 ng/mg protein in controls and 262 +/- 68 ng/mg protein in atopic dermatitis (no statistically significant difference). One control and three patients with atopic dermatitis exhibited a slight, the hyper-IgE patient a marked, elevation of the skin histamine content. No gross differences in the degradation rate of histamine were observed between patients and controls. Acetylcholine and 48/80 induced the same histamine release in both groups; with anti-IgE, almost the double amount of histamine was released from the skin of atopic dermatitis patients as compared to controls. These findings suggest an enhanced releasability of histamine upon immunologic challenge in atopic dermatitis.     

The influence of interferon-gamma and interleukin-4 on IgE production in B lymphocytes of patients with atopic dermatitis. A possible criterion for selection of patients for interferon therapy.

The regulation of IgE production in B lymphocytes of patients with atopic dermatitis by interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) was studied. IL-4 stimulated IgE production in vitro in B-cells of healthy donors and of children with atopic dermatitis, but had only a marginal effect on the high basal level of IgE production by lymphocytes from adult patients with atopic dermatitis. The addition of IFN-gamma prevented in all cases the stimulation of IgE synthesis induced by IL-4. The production of IgG and IgM was differently influenced. These results indicate that the in vitro production of IgE by mononuclear cells from adult patients is more resistant to the regulatory effects of IL-4 and IFN-gamma than is that in B cells of children with atopic dermatitis. We propose that a previous in vitro test of the responsiveness of IgE-producing B cells to IFN-gamma may be used to select patients with atopic dermatitis for treatment with IFN-gamma.