Three suitable antigens for delayed-type hypersensitivity skin testing in a tropical country like Thailand.

Delayed type hypersensitivity (DTH) skin test is a standard tool to assess in vivo cell-mediated immunity. Mantoux method using 4-5 common recalled antigens is recommended. However, not all antigens are widely available and appropriate antigens for tropical countries are not known. The objective of this study is to investigate what and how many antigens should be included in the DTH testing panel that suitable for Thailand and may be for this region. The DTH skin tests were done by Mantoux method in a double blinded fashion. Average induration size of > or = 5 mm defined as a positive test. Antigens included purified protein derivative (PPD), Candida albicans, tetanus toxoid (TT), Trichophyton mentagrophytes and hepatitis B vaccine (HBV). The negative control was normal saline. Of 95 healthy subjects, all showed DTH positive to > or = 1 antigen. The positivity to C. albicans, tetanus toxoid, PPD, T. mentagrophytes, and HBV was 92.6%, 83.2%, 82.1%, 50.5%, and 5.3%, respectively. When three antigens: PPD, TT and C. albicans were analyzed, 100% of subjects showed a positive response to > or = 1 antigen and 96.8% showed a positive response to > or = 2 antigens. When only PPD and TT were analyzed, 100% of subjects showed > or = 1 antigen positive and 68.4% showed both antigens positive. C. albicans antigen at 1:100 was associated with a high incidence of fever (2/20) and large local reaction (7/20), 1:500 was found to be the optimal concentration. PPD, TT and C. albicans are suitable to be included in a DTH skin testing in a tropical country like Thailand. However, in a setting where C. albicans extract is not available, testing with only two antigens of PPD and tetanus toxoid may be an alternative, but with a lower sensitivity.

Association of TNF-alpha, TNF-beta, IFN-gamma and IL-1Ra gene polymorphisms with Graves' disease in the Thai population.

Cytokines play a key role in the regulation of immune and inflammatory responses. Therefore, cytokine genes are potentially related to susceptibility to Graves' disease (GD). The aim of this study was to investigate the putative functional polymorphisms within tumor necrosis factor-alpha (TNF-alpha), tumor necrosis factor-beta (TNF-beta), interferon-gamma (IFN-gamma), and interleukin-1 receptor antagonist (IL-1Ra) genes, in patients with GD (n = 137) compared to a healthy Thai control group (n = 137). The results showed no statistically significant difference between the study groups for TNF-beta (Ncol site in intron 1), IFN-gamma (+874 in intron 1), and IL-1Ra (variable numbers of tandem repeats in intron 2) gene polymorphisms. Only the -863A allele within the promoter region of the TNF-alpha gene, which may affect the affinity of the promoter nuclear factor (NF)-kappab interaction, was found to be increased in GD patients compared to the controls (p = 0.009, OR = 1.8, 95% CI = 1.15 to 2.84). The effect of the -863A allele of the TNF-alpha gene was similar to the autosomal dominance mode of inheritance (p = 0.01, OR = 2, 95% CI = 1.16 to 3.44). This polymorphism may be involved in the susceptibility to GD in part through its higher promoter activity of TNF-alpha production.

No association between an interleukin 4 gene promoter (-589) polymorphism and Graves' disease in Thai patients.

Cytokines play a key role in the regulation of immune and inflammatory responses and therefore are potential candidate genes for autoimmune thyroid disease. Polymorphisms in cytokine genes may effect gene transcription, causing individual variations in cytokine production. Several investigators have linked the interleukin-4 (IL-4) gene and autoimmune disease. The present population-based study was to investigate the polymorphisms of IL-4 gene promoter (-589C/T) in GD patients compared with a control group and determine the association with GD in a Thai population. The subjects included 137 GD patients and 137 healthy control subjects with similar ethnic and geographic backgrounds. The IL-4 gene polymorphism at position -589 in the promoter was analyzed using the PCR-RFLP. The protective effect of the -589T allele as suggested by Hunt et al in a Caucasian population was not observed in the present study. The -589T allele frequencies were similar between patients and control subjects (69% vs 69.3%) suggesting that this polymorphism can not be used as a genetic marker for GD susceptibility in Thais.

Serological analysis of human leukocyte antigens-A and -B antigens in Thai patients with nasopharyngeal carcinoma.

OBJECTIVE: To study the distribution of human leukocyte antigens (HLA) -A and -B antigens by standard microlymphocytotoxicity assay in Thai nasopharyngeal carcinoma (NPC) patients compared to normal controls in order to identify the alleles associated with NPC in Thailand. DESIGN: Retrospective-Analytical study. SUBJECTS: Fifty-three unrelated Thai patients with histologically confirmed NPC diagnosed at King Chulalongkorn Memorial Hospital and 70 healthy unrelated Thai individuals served as controls. METHOD: Lymphocyte separation and HLA typing were performed from freshly drawn blood by standard microlymphocytotoxicity assay. The significance of differences between the two groups was analyzed by the chi-square test. RESULTS: HLA-A2 was observed at a greater frequency in patients being found in 31/53 (58%) NPC patients compared to 27/70 (38%) controls (p = 0.02). An increase in HLA-B46 was also demonstrated. HLA-B46 was present in 16/53 (30%) NPC patients but was observed in 10/70 (14%) in controls (p = 0.03). CONCLUSIONS: This study reported two susceptible, HLA-A2 and HLA-B46 antigens, for NPC in a Thai population.

DRB1*04 subtype in Thai patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) in a Thai population is significantly associated with HLA-DR4. The frequency of DR4 was 43 per cent in RA patients and 20 per cent in the healthy controls (p = 0.00008, OR = 3.06, 95% CI = 1.71, 5.52). To analyze which DR4 alleles were associated with the disease, the authors subtyped 52 DR4-positive RA patients compared to 28 DR4-positive healthy controls by amplification with DR4-specific primers followed by direct sequencing. Six DR4 alleles (DRB1*0401, *0403, *0404, *0405, *0406, and *0410) were found in the RA patient group while 5 alleles (DRB1*0401, *0403, *0405, *0406, and *0407) were found in the control group. Both groups were predominated by DRB11*0405, but there was a significant increase in the frequency of DRB1*0405 in DR4+ RA patients compared to DR4+ healthy controls (84.6% vs 46.4%, p = 0.0008, OR = 6.35, 95% CI = 1.96, 21.08). DR4 which shared epitope alleles (DRB1*0401, *0404, *0405) were observed in 47 (90.3%) DR4+ patients and 15 (53.5%) DR4+ controls (p = 0.0005, OR = 8.15, 95% CI = 2.29, 33.2). In addition, the authors found that DRB1*0403 was significantly decreased in DR4+ RA patients compared to controls (p = 0.0065, OR = 0.07, 95% CI = 0, 0.67).