Ra3 skin test response and HLA-A2, antigen E, and IgE: evidence of interactions between antigen E and HLA

A positive association of Ra3 skin test responses with HLA-A2 has previously been reported to be evident in individuals with low IgE levels and to a greater extent in these individuals than those with high IgE levels. We give evidence based on an analysis of data from 133 individuals that Ra3 response is positively correlated with HLA-A2 among individuals with low Antigen E response and negatively associated with HLA-A2 among individuals with high Antigen E response. Furthermore, we have evidence that any observed interaction between Ra3, IgE, and HLA-A2 can be explained by the correlation between IgE and Antigen E response, and that it is Antigen E response which interacts in the relationship between HLA-A2 and Ra3 skin test response.