LYMPHOCYTE-TRANSFORMATION TEST WITH HOUSE-DUST MITE (DERMATOPHAGOIDES-PTERONYSSINUS) IN NORMAL-CHILDREN, ASTHMATIC-CHILDREN AND ASTHMATIC-CHILDREN RECEIVING HYPOSENSITIZATION

In the first part of this study the proliferative response of lymphocy tes (lymphocyte transformation test) to house dust mite (HDM) stimulat ion in cultures was studied in normal children (n = 16), asthmatic chi ldren who never received hyposensitization (HS) (n = 50) and asthmatic children receiving HS with HDM for at least 6 months (n = 20). The re sults are expressed as disintegrations per minute (d.p.m.) and as stim ulation index (SI = d.p.m. in the presence of the allergen/d.p.m. in t he control culture). A positive SI (> 2) was found in 54% of the asthm atic children who never received HS, in 30% of the asthmatics receivin g HS and in none of the normal children. Furthermore, between asthmati cs with and without HS, the SI was not statistically different, althou gh asthmatics without HS tended to have a higher SI (median value: 2.1 3 vs 1-38) (P= 0.10). In a second series of experiments the effect of adding interleukin-2 (IL-2) to the lymphocyte cell culture was studied in asthmatic children with and without HS. Interleukin-2 induced an a dditional stimulatory effect on the lymphoproliferative response to HD M and to phytohaemagglutinin in patients who never received HS, but ha d no effect in patients receiving HS. We conclude that HS treatment se ems to have an inhibiting effect upon this proliferative response, not only inhibiting the degree of the allergen-induced lymphocyte prolife ration, but also inhibiting the sensitivity of proliferating lymphocyt es for IL-2. These inhibiting effects upon lymphocytic activation coul d be responsible for the anti-inflammatory effects (i.e. suppression o f the late asthmatic reaction) of HS.