ANTIGEN-SPECIFIC IMMUNE RESPONSIVENESS AND LYMPHOCYTE RECRUITMENT IN LEUKOCYTE ADHESION DEFICIENCY TYPE-II

The leukocyte adhesion deficiency syndrome type II (LAD-II) is caused by a general defect in fucose metabolism, which leads to the absence o f fucosylated sugar determinants such as the selectin ligand SLe(x). I n view of the important role of selectins in lymphocyte migration and homing, we have explored the in vivo immune responsiveness and lymphoc yte recruitment to the skin, in response to the neo-antigen keyhole li mpet hemocyanin (KLH) in a LAD-II patient, We observed a normal primin g of KLH-specific T cells as well as a strong in vivo anti-KLH antibod y response, both indicative of a normal T-B cell function and collabor ation. Skin biopsies from the patient's skin taken prior to antigenic challenge showed the presence of normal numbers and subsets of T cells . Upon KLH injection, a large number of T cells were found to be recru ited to the site of challenge, which was paralleled by up-regulation o f the endothelial adhesion molecules ICAM-1 (CD54), VCAM-1 (CD106) and E-selectin (CD62E). The recruited T cell showed a normal subset distr ibution but lacked cutaneous lymphocyte antigen (CLA), the cutaneous h oming receptor. However, the clinical symptoms of delayed-type hyperse nsitivity in the patient (redness and swelling) were severely depresse d compared to that in the controls, In conclusion, the LAD-II patient showed a normal T cell priming and T cell-dependent antibody response, a normal baseline skin homing, and a significant T cell recruitment t o the site of KLH challenge, indicating that fucosylated sugar determi nants such as SLe(x) and CLA are not strictly required for adequate im mune responsiveness and (skin) homing.