In-vivo allergenic potency of Siriraj Mite Allergen Vaccine (SMAV) comparing with standardized vaccine in mite-sensitive patients.

Background: The prevalence of allergic diseases, particularly asthma and allergic rhinitis, has increased tremendously in Thailand and worldwide. House dust mite (HDM) is the major IgE sensitizer among allergic children and adults. We have developed local standardized mite allergen extracts, Siriraj Mite Allergen Vaccine (SMAV) from Dermatophagoides pteronyssinus (Dp) and Dermatophagoides farinae (Df) from our source materials which were highly purified (99%). Objective: To compare in-vivo allergenic potency of both SMAV Dp and Df with commercial standardized mite allergen vaccine by using skin prick testing in mite-sensitive individuals. Methods: This was a double-blind, randomized, self controlled study comparing SMAV and commercial standardized mite allergen vaccine (Dp and Df) by using skin prick testing in mite-sensitive adult volunteers, 18 – 60 years of age. Results: The study was performed in 54 adult volunteers (19 males, mean age 26.6 + 5.5 years old) who had positive skin test to commercial Dp and Df. Seventeen of them had no allergic disease. The most common allergic disease among the volunteers was allergic rhinitis (21/37). Mean wheal diameter of SMAV Dp and commercial Dp at the concentration of 10,000 and 5, 000 AU/ml were equivalent but at the concentration of 2,500 AU/ml was inequivalent. Mean wheal diameter of SMAV Dp was significantly larger than commercial Dp at concentration of 2,500 AU/ml (p < 0.05). Mean wheal diameter of SMAV Df and commercial Df at all 3 concentrations were equivalent. There was no systemic side effect in all subjects. Conclusion: The study demonstrated that in mite-sensitive adults, SPT using SMAV Dp (10,000 AU) and Df (10,000 AU) had equivalent allergenic potency to the commercial comparator without any systemic side effect.

Association between ADAM33 polymorphisms and asthma in a Thai population.

ADAM33 (A Disintegrin And Metalloprotease 33) is an asthma susceptibility gene found across several human populations. However, no information on ADAM33 exists for Thai population. The objective of this study was to determine the association, if any, between ADAM33 polymorphisms and asthma in Thai subjects. Genotyping revealed 8 single nucleotide polymorphisms (SNPs) within the 3' region of the ADAM33 gene among 200 asthmatics and 100 control subjects. Asthmatic subjects were further sub-categorized into high and low severity groups. Multiple genetic model statistic tests for single-marker and haplotype association were carried out. Differences in allele frequencies at the SNPs rs528557/S2, rs598418 and rs44707/ST+4 in asthmatics were statistically significant compared to controls. The SNP rs528557/S2 could also be linked to the low severity group and the SNPs rs598418 and rs44707/ST+4 with the high severity group. Two-SNP haplotype analysis at the SNPs rs528557/S2 and rs598418 revealed a significant association with asthma. This study in a Thai population confirmed a positive association between ADAM33 polymorphisms and asthma susceptibility.

Delayed hypersensitivity skin testing in the Thai adult population.

OBJECTIVE: The present study was carried out in healthy Thai subjects to determine the types and concentrations of standard antigens used in delayed-type hypersensitivity (DTH) skin testing as an evaluation of cell-mediated immunity. MATERIAL AND METHOD: One hundred subjects were tested with three antigens including tuberculin (purified protein derivative), tetanus toxoid, 1:10 and 1:100 dilutions, and Candida albicans, 1:10 and 1:100 dilutions. RESULTS: We found that 92% of the subjects responded to tuberculin and/or tetanus toxoid at a 1:10 dilution, 77% responded to tetanus toxoid at a 1:10 dilution, and 35% responded to a 1:100 dilution. There was only one subject who responded to Candida albicans at a 1:10 dilution, and none to a 1:100 dilution. The size of tuberculin reactions varied from 5 mm to over 20 mm without any evidence of active tuberculosis. CONCLUSION: Tuberculin and tetanus toxoid at a 1:10 dilution are probably sufficient to be used in DTH skin testing to evaluate T-cell function.