Sensitivity and specificity of passive immune‐basophil activation test to detect allergic transfusion reactions

Establishment of a novel human basophil cell line for functional analysis and in vitro allergy testing

BACKGROUND

Basophils are the rarest granulocytes and play diverse roles, e.g., in protective immunity and allergic inflammatory reactions. However, the underlying molecules and mechanisms involved in basophil differentiation and functions, particularly in humans, remain largely unknown. This may be due to the lack of high-quality research tools.

METHODS

We established a novel, immortalized, human basophil cell line by introducing human papillomavirus 16-E6/E7, c-MYC, and BCL-xL gene expression systems into cultured basophils, and evaluated whether this cell line is useful as a research tool, compared with KU812, which is the most commonly-used human basophil cell line.

RESULTS

This cell line expressed various basophil markers, including CD123, CD203c, and the high-affinity immunoglobulin (Ig)E receptor α-chain and can mature into more differentiated cells under specific culture conditions. The differentiated cells stimulated with anti-IgE antibodies showed increased CD203c expression in a dose-dependent manner, whereas the differentiated KU812 cells showed little activation after the stimulation. The established cell line also demonstrated increased sensitivity to allergic activation when stimulated with an allergen (NP-BSA) and allergen-specific IgE (anti-NP-IgE). Furthermore, histamine- and interleukin-4-releasing abilities were also confirmed. These allergic activation profiles were similar to those of basophils from healthy individuals, although the activation levels of the established cells were lower than those of basophils from highly-sensitive individuals.

CONCLUSIONS

These findings suggest that the established basophil cell line has substantially different characteristics from a conventional cell line and could serve as a new tool for investigating basophil differentiation and functions, as well as for testing allergic reactions.

Pilot study on the use of basophil activation tests and skin tests for the prevention of allergic transfusion reactions

Background and objectives

Management of severe allergic transfusion reactions (ATR) is challenging. In this study, we investigate the usefulness of skin tests and basophil activation tests (BAT) in chronically transfused patients for the prevention of future ATR.

Materials and methods

BAT and skin tests were carried with the supernatant of red blood cell (RBC) units for a sickle-cell disease patient under chronic exchange transfusion who has presented a severe ATR, in order to prevent potential future ATR. If the results for both BAT and skin tests were negative, the RBC units could be transfused to the patient. If either one of the results was positive, the tested RBC unit was discarded for the patient.

Results

192 RBC units were tested with both tests. The level of results concordance between the two tests was 95%. Out of the 169 negative units with both tests, 118 units were transfused to the patient for which he presented no ATR.

Conclusion

In our study, combining both BAT and skin tests was associated with a good negative predictive value since we were able to safely transfuse our patient. Further studies are still necessary to confirm this result but this pilot study indicates that skin tests and BAT might help prevent ATR. When BAT is not available, skin tests may also be useful in preventing ATR.

Endotyping of IgE-Mediated Polyethylene Glycol and/or Polysorbate 80 Allergy

BACKGROUND

Polyethylene glycol (PEG) and polysorbate 80 (PS80) allergy preclude from SARS-CoV-2 vaccination. The mechanism(s) governing cross-reactivity and PEG molecular weight dependence remain unclear.

OBJECTIVES

To evaluate PEGylated lipid nanoparticle (LNP) vaccine (BNT162b2) tolerance and explore the mechanism of reactivity in PEG and/or PS80 allergic patients.

METHODS

PEG/PS80 dual- (n = 3), PEG mono- (n = 7), and PS80 mono-allergic patients (n = 2) were included. Tolerability of graded vaccine challenges was assessed. Basophil activation testing on whole blood (wb-BAT) or passively sensitized donor basophils (allo-BAT) was performed using PEG, PS80, BNT162b2, and PEGylated lipids (ALC-0159). Serum PEG-specific IgE was measured in patients (n = 10) and controls (n = 15).

RESULTS

Graded BNT162b2 challenge in dual- and PEG mono-allergic patients (n = 3/group) was well tolerated and induced anti-spike IgG seroconversion. PS80 mono-allergic patients (n = 2/2) tolerated single-dose BNT162b2 vaccination. Wb-BAT reactivity to PEG-containing antigens was observed in dual- (n = 3/3) and PEG mono- (n = 2/3), but absent in PS80 mono-allergic patients (n = 0/2). BNT162b2 elicited the highest in vitro reactivity. BNT162b2 reactivity was IgE mediated, complement independent, and inhibited in allo-BAT by preincubation with short PEG motifs, or detergent-induced LNP degradation. PEG-specific IgE was only detectable in dual-allergic (n = 3/3) and PEG mono-allergic (n = 1/6) serum.

CONCLUSION

PEG and PS80 cross-reactivity is determined by IgE recognizing short PEG motifs, whereas PS80 mono-allergy is PEG-independent. PS80 skin test positivity in PEG allergics was associated with a severe and persistent phenotype, higher serum PEG-specific IgE levels, and enhanced BAT reactivity. Spherical PEG exposure via LNP enhances BAT sensitivity through increased avidity. All PEG and/or PS80 excipient allergic patients can safely receive SARS-CoV-2 vaccines.

Basophil activation test for allergic and febrile non-haemolytic transfusion reactions among paediatric patients with haematological or oncological disease

BACKGROUND AND OBJECTIVES

Allergic transfusion reactions (ATRs) and febrile non-haemolytic transfusion reactions (FNHTRs) are common, although their mechanisms remain unclear. Immunoglobulin E (IgE)-mediated type I hypersensitivity may be involved in the pathogenesis of ATR. A basophil activation test (BAT) may help elucidate this process.

MATERIALS AND METHODS

The BAT was based on peripheral blood samples from paediatric patients with a haematological or oncological disease and on samples of residual blood products transfused in each case. Dasatinib was used to evaluate whether basophil activation was mediated by an IgE-dependent pathway.

RESULTS

Twenty-seven patients with and 19 patients without ATR/FNHTR were included in this study, respectively. The median BAT values associated with ATR- (n = 41) and FNHTR-causing (n = 5) blood products were 22.1% (range = 6.1%-77.0%) and 27.8% (range = 15.2%-47.8%), respectively, which were higher than the median value of 8.5% (range = 1.1%-40.9%) observed in blood products without a transfusion reaction. Dasatinib suppressed basophil activity. BAT values were comparable in patients with ATR regardless of severity. Meanwhile, BAT values analysed with blood products non-causal for ATR/FNHTR were higher in patients with ATR/FNHTR than in those without.

CONCLUSION

The IgE-mediated type I hypersensitivity may be involved in the pathogenesis of ATR and FNHTR. BAT analyses may help elucidate the underlying mechanisms and identify patients at risk.

Relationship between allergic transfusion reactions and allergic predisposition among pediatric patients with hematological/oncological disease

BACKGROUND

Allergic transfusion reactions (ATRs) manifest frequently as transfusion reactions, and their onset may be related to a patient's allergic predisposition. Moreover, although pediatric patients with hematological/oncological disease are more susceptible to ATRs, the relationship between allergic predisposition and ATRs remains to be fully clarified.

STUDY DESIGN AND METHODS

Patients who were diagnosed with pediatric hematological/oncological disease and received transfusion at the study institutions were included. We determined patient background information related to their allergy history, measured the levels of allergen-specific immunoglobulin E (IgE) using sera obtained on diagnosis, and analyzed their associations with ATR onset.

RESULTS

Of the 363 patients analyzed, 144 developed ATRs. Multivariate analysis identified cases with high basophils in the peripheral blood, and Dermatophagoides pteronyssinus- and egg white-specific IgEs were involved in the development of ATR in all age groups. Meanwhile, a history of food allergies, and positivity for Japanese cypress- and D. pteronyssinus-specific IgEs were risk factors for developing ATRs in the <5 years age group. Moreover, patients aged 5-<10 years with a history of asthma, allergic rhinitis, pollinosis, or atopic dermatitis, and those aged ≥10 years with positivity for dog dander-specific IgE were at risk for developing ATRs.

CONCLUSION

The allergic constitution of patients plays a role in ATR onset even in pediatric hematological/oncological diseases. Therefore, advance confirmation of a patient's allergic constitution may partly predict the onset of ATRs. However, since multiple allergic predispositions within complex mechanisms may be involved in the onset of ATRs, further verification is required.

Passive immune basophil activation test for the identification of allergic episodes from various adverse events elicited by haematopoietic cell transplantation: A pilot study

BACKGROUND AND OBJECTIVES

Haematopoietic cell transplantation (HCT) therapy tends to be associated with various complications including engraftment failure, regimen-related toxicities, and infectious diseases. In addition, HC infusion itself occasionally elicits adverse events (AEs), one of the most common AEs is an allergic reaction. As appropriate laboratory tests have not yet been established to distinguish allergy-mediated AEs from other complications, clinical responses for HCT-related AEs can only be nonspecific. In this pilot study, using passive immune basophil activation test (pi-BAT), we attempted to distinguish an HC infusion-induced allergic reaction from various HCT-related AEs.

MATERIALS AND METHODS

Using pi-BAT, we examined 34 patients who underwent HCT, that is, 11 with AEs and 23 without AEs as controls.

RESULTS

Two of the eleven AE cases were pi-BAT positive and, the rest of nine AE cases were negative, while all non-AE cases were negative. Both of the two positive cases showed erythema, tachycardia, plus cough. Because erythema is one of the representative symptom of allergy, those cases could be classified as allergic reaction cases or anaphylaxis cases if tachycardia and cough were concomitant symptoms of erythema. Among the nine AEs with pi-BAT negative result, four cases showed urticaria, four showed vomiting plus diarrhoea, and one showed cough. Urticaria case was strongly suspected of allergy, however, the AE cases were pi-BAT negative.

CONCLUSION

The pi-BAT may be useful as an auxiliary diagnostic tool to confirm the possible involvement of HC infusion in HCT-related AEs and identify an immunologic mechanism for HCT-related hypersensitivity reactions.