Basophil activation testing measured peanut oral immunotherapy desensitization

Basophil activation testing showed that decrease in the log-transformed area under the curve measurements correlated with desensitization in peanut oral immunotherapy, according to research presented at the European Academy of Allergy and Clinical Immunology annual congress in Copenhagen, Denmark.

“Basophil activation testing [BAT] may have a role for diagnosing and monitoring food allergies,” Sarita Patil, MD, instructor, Harvard Medical School, and attending physician in allergy and immunology at Massachusetts General Hospital, told Healio.com. “Our work has been to develop a more automated and reproducible way for analyzing the data that we hope will make the test more useful in clinical settings.”

Sarita Patil

In a single-center, placebo-controlled trial, Patil and colleagues conducted peanut oral immunotherapy (PNOIT) on patients aged 7 to 21 years with IgE-mediated peanut hypersensitivity. Peripheral blood was stimulated by allergens (Arah1, Arah2, Arah6 and whole peanut extract) and stained with fluorescent CCR3 and CD63 antibodies according to Bühlmann FlowCAST assay protocol. Data was used in 100 BAT analyses to define CD63 upregulation by a cutoff set at the 97.5 percentile of CD63 expression of unstimulated basophils. Statistical packages in the Bioconductor R programming language were used to calculate area under the curve (AUC), EC50 and Spearman’s correlation.

“The AUC and log-transformed AUC initially increased early in desensitization (1 month) and subsequently decreased across all allergens, which correlated to serum specific Arah1, Arah2 and peanut IgE,” according to the researchers.

Compared with AUC, the logAUC correlated better with CD63 upregulation against all antigen concentrations (r=0.83 vs. 0.77 Arah1, r=0.78 vs. 0.52 for Arah2, r=0.84 vs. 0.7 for Arah6, r=0.822 vs. 0.64 for peanut). AUC or logAUC showed no correlations with EC50 (r<0.8).

“Moreover, CD63 upregulation at only 2-4 antigen concentrations for each antigen were highly correlated (r=0.8 or greater) with the logAUC: 16 and 80 ng/mL Arah1; 3.2, 16, 80 ng/mL Arah2; 0.64, 3.2, 16, 80 ng/mL Arah6; 1.6, 8, 200 ng/mL peanut,” the researchers wrote.

“The identification of strongly correlated antigen concentrations of logAUC strongly suggests that certain antigen stimulations may be critical in BAT analysis,” the researchers concluded.

For more information:

Patil S. #1621. Presented at: European Academy of Allergy and Clinical Immunology annual congress 2014; June 7-11; Copenhagen, Denmark.

Disclosure: Reagent and partial technical support for the study was provided by Bühlmann Laboratories.