Gleich, Gerald J.

Summary The eosinophil major basic protein (MBP) damages cells including those from organs whose dysfunction is associated with eosinophil infiltration. Concentrations of MBP in the toxic range were found in sputa from asthmatics, in pleural fluid and in sera. These findings suggest the hypothesis that the eosinophil produces damage to cells in disease.

Abstract Although the eosinophil has been recognized as a distinctive cell type for almost 100 years, the major functions of these cells remain unknown. As an approach to defining these functions we have treated guinea pigs with rabbit antiserum to eosinophils (AES) in an attempt to ablate these cells from tissues. Rabbits were immunized thrice with purified eosinophils and the antisera were absorbed with peripheral blood cells from guinea pigs made eosinopenic with methyprednisolone to remove antibodies reactive with serum proteins and erythrocytes. The resulting sera reacted strongly with eosinophils in cytotoxicity tests and had weak or no reactivity with neutrophils. However, absorption of AES with purified neutrophils removed anti-eosinophil activity. Intraperitoneal injection of potent AES into guinea pigs resulted in complete absence of eosinophils from the peripheral blood and from the peritoneal cavity with only transient or no reduction in circulating neutrophils. Eosinophils were also reduced in bone marrow, spleen, and intestine. The ability of neutrophils to absorb AES activity in spite of weak reactivity in cytotoxicity tests may reflect a quantitative difference in antigenic determinants between eosinophils and neutrophils.

Abstract An anti-γM serum which distinguishes between 19SγM and a low-molecularweight γM from human serum (γMs-N) was prepared by immunizing a goat with normal human γM in Freund's complete adjuvant; it was absorbed with γG and hypogammaglobulinemic serum and was specific for γM. The reactivity of this antiserum was examined with 19SγM, with the γM monomer produced by reduction and alkylation (γMs-RA), and with the γM monomer prepared by reduction alone (γMs-R). In agar double diffusion the 19SγM band spurred over the bands formed by γMs-RA and γMs-R whereas the bands formed by γM monomers fused. Mixtures of 19SγM and γMs-RA formed concentric zones of precipitation in radial immunodiffusion and produced two bands in agar double diffusion. By quantitative precipitin analysis, with 19SγM the antiserum contained 30 µg Ab N/0.1 ml serum and with γMs-RA, 19 µg Ab N/0.1 ml. After absorption at equivalence with γMs-RA the antiserum still precipitated with 19SγM and Fc-γM but did not precipitate with Fab-γM. The precipitin reaction between 19SγM and the anti-γM serum absorbed with γMs-RA was inhibited by three γM subunits (γMs-RA, γMs-R, and γMs-N). Thus, the antiserum is reactive with an antigenic determinant on the Fc portion of the µ chain present on both 19SγM and the γM subunits. The difference in the reactivity of the antiserum with 19SγM and the γM subunits may be related to the number of specific antigenic determinants on these molecules.

Summary A naturally occurring low molecular weight γM protein (γMN) was isolated from the serum of a patient with type I dysgammaglobulinemia by preparative electrophoresis and gel filtration. This protein was compared to the macroglobulin (γM19) isolated from the patient’s serum and to the γM subunit (γMS) prepared by reduction and alkylation of γM19. The results indicate that γMN and γMS are similar in size and have the same antigenic determinants. These observations support the concept that the γMN is a naturally occurring subunit of γM19 and is very similar to γMS, γM19, γMN and γMS were also prepared from the patient’s serum after tetanus immunization and were found to bind radiolabeled tetanus toxoid. Most, but not all, controls did not show nonspecific binding of tetanus toxoid. These results suggest but do not conclusively establish the capacity of these γM proteins to bind antigen specifically.

Abstract Eosinophilia and eosinophil activation are recurrent features in various reactive states and certain hematologic malignancies. In patients with hypereosinophilia (HE), HE‐induced organ damage is often encountered and may lead to the diagnosis of a hypereosinophilic syndrome (HES). A number of known mechanisms and etiologies contribute to the development of HE and HES. Based on these etiologies and the origin of eosinophils, HE and HES are divided into primary forms where eosinophils are clonal cells, reactive forms where an underlying reactive or neoplastic condition is detected and eosinophils are considered to be “non‐clonal” cells, and idiopathic HE and HES in which neither a clonal nor a reactive underlying pathology is detected. Since 2012, this classification and the related criteria have been widely accepted and regarded as standard. However, during the past few years, new developments in the field and an increasing number of markers and targets have created a need to update these criteria and the classification of HE and HES. To address this challenge, a Working Conference on eosinophil disorders was organized in 2021. In this conference, a panel of experts representing the relevant fields, including allergy, dermatology, hematology, immunology, laboratory medicine, and pathology, met and discussed new markers and concepts as well as refinements in definitions, criteria and classifications of HE and HES. The outcomes of this conference are presented in this article and should assist in the diagnosis and management of patients with HE and HES in daily practice and in the preparation and conduct of clinical trials.

AbstractBackgroundBiomarkers of eosinophilic disease activity, especially in the context of novel therapies that reduce blood eosinophil counts, are an unmet need. Absolute eosinophil count (AEC) does not accurately reflect tissue eosinophilia or eosinophil activation. Therefore, the aims of this study were to compare the reliability of plasma and urine eosinophil major basic protein 1, eosinophil cationic protein, eosinophil‐derived neurotoxin (EDN), and eosinophil peroxidase measurement and to evaluate the usefulness of eosinophil granule protein (EGP) measurement for the assessment of disease activity in patients with eosinophil‐associated diseases treated with mepolizumab, benralizumab, or dexpramipexole.MethodsEosinophil granule protein concentrations were measured in serum, plasma, and urine from healthy volunteers and patients with hypereosinophilic syndrome (HES), eosinophilic granulomatosis with polyangiitis (EGPA), and eosinophilic asthma using a multiplex assay.ResultsUrine EGP concentrations remained stable, whereas serum and plasma EGP concentrations increased significantly with delayed processing. Plasma (p) EDN, but not urine (u) EDN, concentration correlated with AEC and negatively correlated with prednisone dose. Both pEDN and uEDN decreased significantly following treatment of HES patients with benralizumab and EGPA patients with mepolizumab. uEDN appeared to increase with clinical relapse in both patient groups.ConclusionsMeasurement of EGP in urine is noninvasive and unaffected by cellular lysis. Although plasma and urine EDN concentrations showed a similar pattern following benralizumab and mepolizumab treatment, the lack of correlation between AEC or prednisone dose and uEDN concentrations suggests that measurement of uEDN may provide a potential biomarker of disease activity in patients with HES and EGPA.

A 9-year-old girl had fever, life-threatening interstitial pneumonia, a vesicular skin rash, parotid and submandibular swelling, and marked blood eosinophilia (WBC count 47,000/µL, 39% eosinophils). Results of lung and skin biopsies showed vasculitis with intense eosinophil infiltration. Immunofluorescence analyses of these biopsies, as well as analysis of tissue from the parotid, lip, and trachea, showed striking deposition of eosinophil granule major basic protein associated with areas of tissue damage. Treatment with glucocorticoids and hydroxyurea produced clinical improvement. The association between tissue damage and deposition of the cytotoxic major basic protein suggests that the eosinophil contributed to the pathophysiology of this disease. Recognition of the capacity of the eosinophil to produce tissue damage can be helpful in the selection of therapy.

An infant with Hodgkin's disease and thymic alymphoplasia is described. The infant died at 5 months of age after an illness clinically characterized by frequent respiratory infections, erythematous rash, oral thrush, and hepatosplenomegaly. The peripheral blood showed severe anemia and lymphopenia; IgG level was very low, and there was no mitosis of peripheral lymphocytes after stimulation with phytohemagglutinin. Autopsy revealed Pneumocystis carinii pneumonia, thymic alymphoplasia, and Hodgkin's lymphoma in lymph nodes, liver, spleen, and lungs. A reovirus type 3 was isolated from the lungs. The association of diseases as rare as Hodgkin's disease and thymic alymphoplasia suggests a relationship between them. This may consist of either an abnormal susceptibility to oncogenic virus or an inability to destroy mutant cells in an infant with congenital immunologic-deficiency syndrome.

Abstract Background: Eosinophils play an important role in allergic inflammation. Glucocorticosteroids have been used as an anti-inflammatory medication for inflammatory diseases involving eosinophil infiltration. Some effect of nebulized lidocaine has been reported when treating certain patients with asthma, which is also an inflammatory disease. The goal of this study was to examine the effects of dexamethasone and lidocaine on eosinophil proliferation and differentiation using a model of human umbilical cord blood mononuclear cells (UCMC) cultured with IL-5. Methods: UCMC were cultured with IL-5 (5 ng/mL) for 4 weeks. The effects of dexamethasone and lidocaine on the number and morphology of eosinophilic cells were visualized with Wright-Giemsa and cyanide-resistant peroxidase stains. Moreover, the effect on eosinophil-derived neurotoxin (EDN) and eosinophil peroxidase (EPX) contents in cultured cells were evaluated using radioimmunoassay.Results: The number of eosinophilic cells and EDN and EPX content in cultured cells increased in a time-dependent manner in the presence of IL-5. Dexamethasone treatment slightly decreased the number of eosinophilic cells in one week, but this effect was lost in 2–4 weeks. Macrophages in cultured UCMC treated with dexamethasone contained more eosinophil granule proteins. Both EDN and EPX content in cultured cells were reduced by dexamethasone. Lidocaine decreased the number of eosinophilic cells and reduced both EDN and EPX contents in cultured cells.Conclusions: Dexamethasone suppressed the production of eosinophil granule proteins and may also induce apoptosis of eosinophils, while lidocaine suppresses eosinophilopoiesis.

Abstract Background: Eosinophils play an important role in allergic inflammation . Glucocorticosteroids have been used as an anti-inflammatory medication for inflammatory diseases involving eosinophil infiltration. Likewise, lidocaine, a local anaesthetic, is used to treat certain patients with asthma, which is also an inflammatory disease. The goal of this study was to examine the effects of dexamethasone and lidocaine on eosinophil proliferation and differentiation using a model of human umbilical cord blood mononuclear cells (UCMC) cultured with IL-5.Methods: UCMC were cultured with IL-5 (5 ng/mL) for 4 weeks. The effects of dexamethasone and lidocaine on the number and morphology of eosinophilic cells were visualized with Wright-Giemsa and cyanide-resistant peroxidase stains . Moreover, the effect on eosinophil-derived neurotoxin (EDN) and eosinophil peroxidase (EPX) contents in cultured cells were evaluated using radioimmunoassay.Results: The number of eosinophilic cells and EDN and EPX content in cultured cells increased in a time-dependent manner in the presence of IL-5. Dexamethasone treatment slightly decreased the number of eosinophilic cells in one week, but this effect was lost in 2–4 weeks. Macrophages in cultured cells treated with dexamethasone contained more eosinophil granule proteins when UCMC were treated with dexamethasone. Both EDN and EPX content in cultured cells were reduced by dexamethasone. Lidocaine decreased the number of eosinophilic cells and reduced both EDN and EPX contents in cultured cells. Conclusions: These findings suggest that dexamethasone suppresses eosinophil maturation while lidocaine suppresses both production and maturation. Dexamethasone may also induce apoptosis of eosinophils.