Objective. Atopic asthma provides a useful model for evaluating the genetic factors that control human immune responsiveness. HLA class Ⅱ gene products are involved in the control of immune response. As HLA-DRB gene is the most polymorphic HLA class Ⅱ gene

we investigated whether susceptibility or resistance to the disease is associated with HLA-DRB. Methods. Blood samples were obtained from two groups of unrelated Chinese northern adults: （l） 50 atopic asthma （7 of them with familial aggregation） ;（2） 80 healthy controls without asthma or atopy and other HLA-associated diseases. Genomic DNA was extracted from peripheral venous blood leucocytes. The polymorphic second exon of HLA-DRB gene was amplified by sequence-specific primer polymerase chain reaction （SSP/PCR） methods. All patients had their serum IgE （total and specific） antibody levels by RAST

bronchial reactivity assessed by methacholine brocho-provocation test and/or bronchodilation test. Results. There was an increased gene frequency of DR

6（13）

and DR

52

in asthmatic subjects compared with healthy subjects（17% vs 4. 3%

P

<

0.01; 50% vs 17. 5 %

P

<

0. 01 ）

and the decreased frequency of DR

2（15）

and DR

51

in asthmatic patients（7% vs 18%

P

<

0. 05; 2 % vs 33 %

P

<

0. 01 ）. We found the positive association between DR

6（13）

-DR

52

and sIgE antibody responsiveness to dl （from house dust mite al- lergen ）; negative association between HLA-DRB alleles and TIgE or BHR （bronchial hyperresponsiveness ）. Conclusion. The results suggested that HLA haplotype DR

6（13）

-DR52 was significantly implicated in sus- ceptibility to house dust mite induced-asthma

at least it would be more closely associated with atopic asth- ma. Conversely

alleles DR

2（15）

and DR

51

might confer protection against the disease. HLA-DRB genes were particularly involved in regulating human atopic immune response in asthma.