Basophil Tests Research Articles

Skin tests, serological IgE detection, basophil test—what is available, useful and helps to clarify a mold allergy?

AbstractThe prevalence of sensitization to molds is low in healthy people, but significant in asthmatics. As it has not yet been possible to establish a cause-and-effect relationship between the presence of mold allergens and the occurrence of allergic symptoms, there is a great deal of uncertainty. The update of the S2k guideline “Medical–clinical diagnostics for indoor mold exposure” should help to objectify the topic. Based on the recommendations listed there for the diagnosis of suspected IgE-mediated mold allergy, this article presents the possibilities of skin tests, IgE determinations, and other in vitro test options, but also their limitations in clarifying the cause. Potential possibilities include component-resolved allergy diagnostics, while the limitations include the difficult standardization of test allergen extracts due to the complex allergen source and the insufficient commercial availability of the test extracts. A diagnostic algorithm is presented as a tool for a systematic approach to patients with suspected mold-associated respiratory allergy.

Opioid toxicity: histamine, hypersensitivity, and MRGPRX2.

Insights into the pathophysiology of many non-immune-mediated drug reactions referred to as toxicities, sensitivities, intolerances, or pseudoallergies have resulted from research identifying the mastocyte-related G-protein-coupled receptor (GPCR) member X2 (MRGPRX2), a human mast cell receptor mediating adverse reactions without the involvement of antibody priming. Opioid-induced degranulation of mast cells, particularly morphine, provoking release of histamine and other preformed mediators and causing hemodynamic and cutaneous changes seen as flushing, headache and wheal and flare reactions in the skin, is an example of results of MRGPRX2 activation. Opioids including morphine, codeine, dextromethorphan and metazocine as well as endogenous prodynorphin opioid peptides activate MRGPRX2 at concentrations causing mast cell degranulation. Unlike the canonical opioid receptors, MRGPRX2 shows stereochemical recognition preference for dextro rather than levo opioid enantiomers. Opioid analgesic drugs (OADs) display a range of histamine-releasing potencies from the strong releaser morphine to doubtful releasers like hydromorphone and the non-releaser fentanyl. Whether there is a correlation between histamine release by individual OADs, MRGPRX2 activation, and presence or absence of adverse cutaneous effects is not known. To investigate the question, ongoing research with recently pursued methodologies and strategies employing basophil and mast cell tests resulting from MRGPRX2 insights should help to elucidate whether or not an opioid's histamine-releasing potency, and its property of provoking an adverse reaction, are each a reflection of its activation of MRGPRX2.

Investigation of the effects of pneumatic tube transport system on routine biochemistry, hematology, and coagulation tests in Ankara City Hospital.

Academics are far from a consensus regarding the effects of pneumatic tube system (PTS) delivery on sample integrity and laboratory test results. As for the reasons for conflicting opinions, each PTS is uniquely designed, sample tubes and patient characteristics differ among studies. This study aims to validate the PTS utilized in Ankara City Hospital for routine chemistry, coagulation, and hematology tests by comparing samples delivered via PTS and porter. The study comprises 50 healthy volunteers. Blood samples were drawn into three biochemistry, two coagulation, and two hemogram tubes from each participant. Each of the duplicate samples was transferred to the emergency laboratory via Swiss log PTS (aka PTS-immediately) or by a porter. The last of the biochemistry tubes were delivered via the PTS, upon completion of coagulation of the blood (aka PTS-after). The results of the analysis in these groups were compared with multiple statistical analyses. The study did not reveal any correlation between the PTS and serum hemolysis index. There were statistically significant differences in several biochemistry tests. However, none of them reached the clinical significance threshold. Basophil and large unidentified cell (LUC) tests had poor correlations (r=0.47 and r=0.60; respectively) and reached clinical significance threshold (the average percentages of bias, 10.2%, and 15.4%, respectively). The remainder of the hematology and coagulation parameters did not reach clinical significance level either. The modern PTS validated in this study is safe for sample transportation for routine chemistry, coagulation, and hematology tests frequently requested in healthy individuals except for basophil and LUC.

Autologous serum skin test reactions in chronic spontaneous urticaria differ from heterologous cell reactions.

Autoimmune chronic spontaneous urticaria (CSU) is due to mast cell (MC)-activating autoantibodies, which are screened for by the autologous serum skin test (ASST) and basophil tests (BTs). Many CSU patients are positive in only one of these tests. How often this occurs and why is currently unknown. To characterize the prevalence of mismatched ASST and BTs in CSU patients, and to investigate possible reasons for these mismatches. We determined the rates of ASST+/BT- and ASST-/BT+ mismatches in published CSU studies. We assessed sera from 48 CSU patients by ASST, two BTs (basophil histamine release assay, BHRA; basophil activation test, BAT), a MC histamine release assay (MCHRA) and by ex vivo skin microdialysis (SMD). The ASST/BT mismatch rate in published CSU studies was 31% (ASST+/BT-: 22%, ASST-/BT+: 9%). In our patients, the ASST/BHRA and ASST/BAT mismatch rate was 35.4% (ASST+/BHRA-: 18.8% and ASST-/BHRA+: 16.7%) and 31.3% (ASST+/BAT-: 6.3% and ASST-/BAT+: 25.0%), respectively, and the two BTs were significantly correlated (P=0.0002). The use of heterologous MCs, in vitro and in situ, instead of basophils produced similar results (MCHRA mismatch: 47.9%, ASST+/MCHRA-: 18.8%, ASST-/MCHRA+: 29.2%; SMD mismatch: 40.0%, ASST+/SMD-: 10.0% and ASST-/SMD+: 30.0%), and the MCHRA was highly correlated with SMD results (P=0.0002). The ASST and BTs show divergent results in a third of CSU patients. Mismatches cannot be explained by the choice of basophil assay, the type of heterologous cells exposed to CSU serum in vitro (basophils vs. mast cells), nor the experimental setting of heterologous skin mast cells (in vitro vs. in situ). Thus, serum-induced whealing, in CSU patients, seems to involve autologous skin signals modulating MC degranulation.

Базофильный тест в практической медицине

Базофильный тест в практической медицине

A comparative study on basophil activation test, histamine release assay, and passive sensitization histamine release assay in the diagnosis of peanut allergy.

Allergy can be diagnosed using basophil tests. Several methods measuring basophil activation are available. This study aimed at comparing basophil activation test (BAT), histamine release assay (HR), and passive sensitization histamine release assay (passive HR) in the diagnosis of peanut allergy. BAT, HR, and passive HR were performed on 11 peanut-allergic and 14 nonallergic subjects. Blood was incubated with peanut extract or anti-IgE and tests were performed as follows: BAT-CD63 upregulation was assessed by flow cytometry; HR-released histamine was quantified by a glass fiber-based fluorometric method; passive HR-IgE-stripped donor basophils were incubated with participants' serum and histamine release was quantified as HR. CDsens, a measure of basophil allergen sensitivity, was significantly higher for BAT (80.1±17.4) compared to HR (23.4±10.31) and passive HR (11.1±2.0). BAT, HR, and passive HR had a clinical sensitivity of 100%, 100%, and 82% and specificity of 100%, 100%, and 100%, respectively, when excluding inconclusive results. BAT identified 11 of 11 allergic patients, HR 10, and passive HR 9. Likewise, BAT recognized 12 of 14 nonallergic subjects, HR 10, and passive HR 13. However, the tests' diagnostic performances were not statistically different. Interestingly, nonreleasers in HR but not in BAT had lower basophil count compared to releasers (249 vs 630 counts/min). BAT displayed a significantly higher CDsens compared to HR and passive HR. The basophil tests' diagnostic performances were not significantly different. Still, BAT could diagnose subjects with low basophil number in contrast to HR.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

The Editor takes a closer look at some of this month's articles

Clinical & Experimental AllergyVolume 45, Issue 10 p. 1477-1477 Editor's ChoiceFree Access The Editor takes a closer look at some of this month's articles First published: 15 September 2015 https://doi.org/10.1111/cea.12629AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Viral immunity: key differences between the gut and lung in asthma Rhinoviruses play an important part in asthma exacerbations, and viral antibody titres against these members of the enterovirus genus are higher in asthmatic children than healthy controls. Iwasaki et al. (pp. 1523–1530) have asked whether this was also the case for the gut tropic enteroviruses echovirus 30, which causes an acute febrile illness in children, and the Sabin 1 poliovirus. They found that IgG titres against echovirus, but not poliovirus, were lower in asthmatic children compared to matched healthy controls. Whether this was due to a protective effect of echovirus infection on the development of asthma or a diminished antibody immune response to echovirus in asthmatics is not clear. However, the study emphasizes the potential importance of differential, organ-specific, mucosal immune responses in the development of asthma. Jua Iwasaki Total (a) and species-specific (b) IgG1 antibody binding to echovirus 30 VP1 and human Sabin 1 poliovirus VP1 antigens in Emergency Department (ED) asthmatics and nonasthmatic children. [See Figure 1b in J. Iwasaki et al. (pp. 1523–1530)]. Predicting anaphylaxis with bee venom immunotherapy: a role for the basophil test? Measuring the sensitivity of basophil activation to in vitro allergen challenge, either by mediator release or changes in receptor expression, has been a test without an established clinical role for a long time. Korošec et al. (pp. 1579–1589) have investigated which factors including basophil sensitivity predict allergic reactions to ultra-rush immunotherapy for bee venom anaphylaxis. They studied a range of clinical and immunological measurements in 93 patients, 13 of whom had severe systemic reactions (5 had to have their IT stopped). Pre-treatment basophil sensitivity was the only independent predictor of both a severe systemic reaction and having to stop treatment. A useful test therefore for groups which undertake this approach to bee venom IT. Peter Korosec A bee. (Photo credit: James Petts, London, England; Wikimedia Commons). Prostaglandin E2: how can we harness its protective properties? It has been known for many years that prostaglandin E2 has bronchoprotective properties on both airway inflammatory cells and airway smooth muscle contraction, but so far this potent inhibitory pathway has not been exploited in drug development 1. In part, this is because the exact mechanisms involved remain unclear. Further clarity is brought to the subject by Torres et al. (pp. 1590–1600) who have investigated the effects of PGE2 in the asthma allergen challenge model using two strains of mice; BALB/c which is a mast cell-dependent model and C57BL/6 mice which is mast cell independent. They convincingly demonstrate that the inhibitory properties of PGE2 on inflammation and airway hyperresponsiveness are mast cell dependent and mediated through the mast cell E prostanoid 2 (EP2) receptor. There must be a therapeutic target somewhere in this pathway. Rosa Torres and Mariona Serra The molecular structure of Prostaglandin E2. (Photo credit: NEUROtiker; Wikimedia Commons). Reference 1Pavord ID, Tattersfield AE. Bronchoprotective role for endogenous prostaglandin E2. Lancet 1995; 345: 436– 8. Caption to cover illustration: Immune mechanisms of tolerance and sensitization to foods. [See figure 1 of M. C. Berin (pp. 1483–1496)]. This logo highlights the Editor's choice articles on the cover and the first page of each of the articles. Volume45, Issue10October 2015Pages 1477-1477 ReferencesRelatedInformation

Evaluación de técnicas inmunológicas in vitro para el diagnóstico de alergias: metanálisis 2000-2012

Allergies have high prevalence, affecting all age groups, generate negative impacts on health, educational and economic systems, and they are unknown the diagnostic utility of screening tests. The objective of the study was to evaluate the validity, performance, safety and diagnostic efficiency of in vitro immunological techniques for allergies, 2000-2012. Systematic review with meta-analysis. We applied a search strategy studies in PubMed, Sciencedirect and Wiley, with search terms activation basophil test, lymphocyte transformation test, especific IgE immunoassay. We determined the reproducibility of the selection, extraction and quality assessment of articles. We calculated sensitivity, specificity, likelihood ratios, predictive values, proportion of false, accuracy, odds ratio, Youden index J and ROC curve in Meta-DiSc(es) and Epidat 3.0. software. We included 18 studies with 3520 individuals, 58% patients and 42% healthy. Activation of basophils showed sensitivity of 78% (95% CI :74-81), specificity 95% (95% CI: 83-100), positive likelihood ratio 9.9 (95% CI: 6.8 to 14.4) and negative of 0.20 (95% CI = 0.13 to 0.30) a diagnostic OR 70.8 (IC95: 40.2 to 124.8) and area under the curve of 0.97. In specific immunoglobulin E sensitivity was 72% (95% CI: 69-75), specificity 90% (95% CI : 88-92), positive likelihood ratio 12.9 (95% CI = 4.0 to 41.6) negative 0.32 (95% CI:0.23-0.43), diagnostic OR 41.6 (95% CI :11.6 to 148.9) and area under the curve 0.87. We showed that activation of basophils and specific IgE are useful tests for diagnosing allergies.

Differentiating the Cellular and Humoral Components of Neuromuscular Blocking Agent–Induced Anaphylactic Reactions in Patients Undergoing Anaesthesia

Background The significance of IgE antibodies to neuromuscular blocking agent (NMBA)-induced anaphylactic reactions during anaesthesia is unclear. We investigated the relevance of IgE to rocuronium using an in vitro technique. Methods Serum samples from 61 patients with anaphylactic reactions during anaesthesia were investigated. On the basis of clinical history, allergy to NMBA was considered likely in 48 patients, further assessed using intradermal skin tests for several commonly used NMBAs, including rocuronium, vecuronium, and succinylcholine. To determine the presence of rocuronium IgE in human serum, a rocuronium-human serum albumin (rocHSA) conjugate was coupled to a solid phase and a radioallergosorbent test performed. The biological effects of patient serum NMBA-IgE on histamine release were investigated using in vitro sensitized basophils from healthy blood donors. Results IgE to rocuronium was found in 23 of 48 serum samples (48%) with NMBA allergy, although only two of these were able to sensitize basophils to release histamine in response to rocHSA. IgE-responsiveness in the basophil test was only observed with conjugated rocHSA and not with unconjugated rocuronium or the other NMBAs evaluated. However, unconjugated rocuronium inhibited the histamine release induced by rocHSA. Correlation between skin-test reactivity to rocuronium and IgE to rocHSA was low (P>0.1). In contrast, striking correlation between IgE to rocuronium and skin-test reactivity to succinylcholine was found (P Conclusions Our results indicate that NMBA-related anaphylaxis requires not only IgE NMBA reactivity, but also altered cellular reactivity in the patient. The latter may be demonstrable by testing basophils from the patient, a skin test with (steroidal) NMBA, or both.

Differentiating the cellular and humoral components of neuromuscular blocking agent-induced anaphylactic reactions in patients undergoing anaesthesia

The significance of IgE antibodies to neuromuscular blocking agent (NMBA)-induced anaphylactic reactions during anaesthesia is unclear. We investigated the relevance of IgE to rocuronium using an in vitro technique. Serum samples from 61 patients with anaphylactic reactions during anaesthesia were investigated. On the basis of clinical history, allergy to NMBA was considered likely in 48 patients, further assessed using intradermal skin tests for several commonly used NMBAs, including rocuronium, vecuronium, and succinylcholine. To determine the presence of rocuronium IgE in human serum, a rocuronium-human serum albumin (rocHSA) conjugate was coupled to a solid phase and a radioallergosorbent test performed. The biological effects of patient serum NMBA-IgE on histamine release were investigated using in vitro sensitized basophils from healthy blood donors. IgE to rocuronium was found in 23 of 48 serum samples (48%) with NMBA allergy, although only two of these were able to sensitize basophils to release histamine in response to rocHSA. IgE-responsiveness in the basophil test was only observed with conjugated rocHSA and not with unconjugated rocuronium or the other NMBAs evaluated. However, unconjugated rocuronium inhibited the histamine release induced by rocHSA. Correlation between skin-test reactivity to rocuronium and IgE to rocHSA was low (P>0.1). In contrast, striking correlation between IgE to rocuronium and skin-test reactivity to succinylcholine was found (P<0.001). Our results indicate that NMBA-related anaphylaxis requires not only IgE NMBA reactivity, but also altered cellular reactivity in the patient. The latter may be demonstrable by testing basophils from the patient, a skin test with (steroidal) NMBA, or both.

Endogenous haematological rhythm in dogs

The present study was carried out in 2008 with the aim of analysing the various haematological variables in dogs submitted to different photoperiods. Six Collie dogs were divided into two groups and exposed to different photoperiods. One group received light-darkness cycle (LD) 10:14 and the other LD 24:00. In both photoperiods, blood samples were taken from the jugular vein at 2-h intervals over a 24-h period. All blood samples underwent erythrocyte, haemoglobin, haematocrit, leukocyte, lymphocyte, monocyte, neutrophil, eosinophil, basophil and platelet concentration tests. Haematological variables were measured with a haematological counter and analysed by repeated measures using ANOVA and Cosinor analysis. In those canines subjected to a natural LD variation, the environmental signals reset the period and biological rhythm phase daily and all the variables analysed showed chronobiological variations that adjusted to daily patterns. In free-running conditions, the erythrocyte, haemoglobin, haematocrit and platelet variables present ultradian variations, as well as a period variation range among individuals caused by lack of the synchronising geophysical phenomenon, while the biological rhythms for leukocytes, lymphocytes, monocytes, neutrophils and basophils are manifested in free-running conditions, revealing the endogenous biological clock action.

Assays for measuring in vitro basophil activation induced by recombinant allergens

The diagnosis of type I allergy is essentially based on clinical data, skin tests, and measurements of allergen-specific IgE. However, the determination of specific IgE per se does not permit a definitive conclusion concerning the response of effector cells to the respective allergen(s) and consecutive clinical symptoms in all patients. In an attempt to overcome this problem, a number of basophil-activation assays have been developed during the last few years. Today, allergen-induced activation of blood basophils can be employed as a specific and reliable measure of IgE-dependent responses in sensitized individuals. Using recombinant allergens and basophil-specific markers, these novel assays appear to serve as simple and useful tests in component-resolved diagnosis of type I allergies. In the current article, the biochemical, functional, and technical background of these basophil tests is discussed.

Influence of the diluent on the effect of highly diluted histamine on basophil activation

Background: In modern pharmaceutical practice, it is common to use purified ethanol and purified water for the preparation of homeopathic dilutions. Hahnemann in 1827 recommended good brandy as a diluent. Brandy contains a lot of accompanying substances in addition to ethanol. Purpose of the study: The research question was whether different diluents influence the effectiveness of high dilutions, especially above Avogadro's number. We compared two dilution media to investigate the diluent's influence. Within the limitations of the test-system, the dilution media were as similar to good brandy as possible and like purified ethanol. Dilutions of histamine were prepared with both media. As test-system, we used modified basophil activation in an in vitro cell system. Basophils are activated by anti-immunoglobulin E (anti-IgE). The activation of basophils is inhibited by prior incubation with histamine. The reduction in activation was measured with different dilutions of histamine. The test system used a 3-colour flow cytometric method. The interleukin-3 (IL-3) receptor CD123 was used to identify basophils in the leukocyte mixture. The CD63 surface marker was used for quantification of activated basophils. Results: With higher concentrations of histamine, we observed inhibition on optimally anti-IgE-stimulated basophil activation with a clear concentration dependency. With low concentrations of histamine (up to 10 -31), we also observed inhibition of IgE-mediated basophil activation. Differences were observed between the dilution media. Conclusion: The preliminary results support the hypothesis that the dilution medium may influence the effects of high dilutions. This could be of importance for homeopathic pharmaceutical practice as well as for ultra-high dilution experiments. The refined basophil test system proved to be highly sensitive and reliable. Further studies are needed.

Flour Allergy in Bakers

Extract of wheat flour obtained by extraction, centrifugation and dialysis was immunochemically characterized by quantitative immunoelectrophoresis using rabbit antibodies. The analysis revealed wheat flour to be composed of 40 antigens, some of which were immunologically partially identical with antigens of rye flour and of common grass pollen. Furthermore, antigens of the gliadin fraction of wheat flour were identified. 25 bakers with allergic complaints working in and around Copenhagen were clinically tested with wheat flour and related extracts. Among 13 bakers with respiratory complaints (asthma and/or rhinitis), 11 showed positive reactions to wheat flour extract when tested in histamine release from basophil leukocytes radioallergosorbent test and skin test, whereas further 2 were positive in the basophil test only. The ability of the IgE of individual sera to adsorb to the individual antigens of wheat flour was examined by means of crossed radioimmunoelectrophoresis. On the basis of these results, individual allergenic components of wheat flour were identified, three of these with comparatively high affinity and frequency.

Studies on the degranulation of human basophil leucocytes in vitro.

SUMMARY.— Ninety-five subjects were examined clinically and skin tested for immediate and delayed type hypersensitivity. Their basophils were subjected to direct degranulation tests. Of 32 of those with definite evidence of Type 1 “immediate” hypersensitivity, 21 showed excessive degranulation of their basophils when exposed to specific allergen in vitro. None of 9 patients with allergic contact dermatitis or of 11 patients with chronic non-allergic urticaria gave a positive direct basophil test. Forty-three normal subjects also gave negative tests. Sera from 48 normal and allergic subjects were tested in the indirect system using rabbit basophils. A non-specific toxic effect on the basophils was found in 19 of these. Of 19 allergic sera, which were not toxic, 13 caused degranulation of rabbit basophils in vitro. None of the 10 non-toxic normal sera caused degranulation. The implications of these findings are discussed.

Penicilloyl-Polylysine Skin Test:

THE PRESENT report documents the view that intradermal skin testing with the synthetic polyfunctional hapten of penicillin, ie, penicilloylpolylysine (PPL), poses the hazard of anaphylaxis. In addition, it illustrates the fact that antigen specificity may remain in such a narrow band that the PPL skin test fails to indicate what the patient's reaction to penicillin G may be. Admittedly unusual, the following experience has been extracted from our investigations of adverse drug reactions. 1 Report of a Case This 30-year-old, healthy, white man gave a history of having developed a delayed papular eruption following potassium penicillin G therapy six years ago. Treatment with penicillin had been avoided in the interim. The following observations were made: Absolute circulating basophil count was 29/cu mm (normal range = 20 to 50). Results from a penicillin G direct basophil test 2 (dilution 1/600) were negative. Results from the penicillin G histamine release test (indirect rabbit)

FURTHER EXPERIENCES WITH THE INDIRECT BASOPHIL TEST.

The present status of the basophil degranulation test has been reviewed. Current experience in our laboratory is outlined and selected patient examples cited. The basophil test continues to be a helpful diagnostic tool for detecting circulating anaphylactic antibodies.

Basophil degranulation tests in atopic allergic states: A pilot study of ragweed pollen sensitive patients

Of 22 patients with clinically active hay fever and positive skin tests to ragweed pollen extract, 27 per cent gave positive basophil tests with the use of the same extract. One half of these positive test reactors had received hyposensitization therapy One of 12 nonallergic controls gave a positive basophil test with the same extract. The basophil test, as performed by the methods described, does not lend itself to practical application in the detection of the ragweed-sensitive patient.

THE CIRCULATING BASOPHIL AS AN INDICATOR OF HYPERSENSITIVITY IN MAN. EXPERIMENTAL NOVOBIOCIN SENSITIZATION.

Twenty-five healthy male volunteers received novobiocin orally for 15 days. One third of these subjects showed an increase in the percentage of circulating basophils which was interpreted as an immune response. Later challenge of one of these subjects with novobiocin caused a reactive basophilia within 24 hours. One of the men developed a typical ninth-day erythema or morbilliform eruption as a result of novobiocin sensitization. This individual regularly showed a unique and dramatic drop in the percentage of basophils within four hours of readministration of the drug. Such a basopenic response may be used diagnostically. Indirect basophil tests were negative for urticarial or anaphylactic antibodies in all 25 subjects. However, one subject did develop a novobiocin-induced serum toxicity for the rabbit basophil.