Detection of blocking antibodies after hyposensitization.

We have studied two techniques and developed another to detect blocking antibodies in allergic asthmatic children who have been exposed to seven months of hyposensitization to house dust. These techniques were: RAST Neutralization test (RAST-N), RAST Interference test (RAST-I) and RAST Previous Adsorption test (RAST-PA). We have also determined the specific IgE values, by radioallergosorbent test (RAST), before and after the treatment and have not found a significant decrease in these levels. The percentages of positive development of blocking antibodies obtained were: 28% by RAST-N, 80% by RAST-I and 28% by RAST-PA. Thus, RAST Interference test seems to be more sensitive concerning the qualitative determination of blocking antibodies.