PREFERENTIAL RECRUITMENT OF ACTIVATED, MEMORY T-LYMPHOCYTES INTO SKINCHAMBER FLUIDS DURING HUMAN CUTANEOUS LATE-PHASE ALLERGIC REACTIONS

To determine whether activated memory T lymphocytes (CD3(+)CD4(+)CD45R O(+)CD25(+)HLA-DR(+)) preferentially accumulate during the cutaneous I gE-dependent fate-phase response, we challenged 10 atopic patients wit h allergen and monitored the cellular influx for 12 hours with a skin blister chamber model. Four patients with allergy were also challenged with irrelevant allergen in control experiments. Histamine release an d the size of the cutaneous fate-phase response were measured. Light m icroscopic analysis and phenotyping of recruited and blood lymphocytes were performed with immunofluorescence and flow cytometry. Antigen ch allenge induced significant histamine release, a macroscopic late-phas e response, and significant cellular influx in the appropriately chall enged patients with allergy but not in control subjects. In the contro l group, only limited phenotypic analyses could be performed, which de monstrated an equivalent percentage of CD3(+)CD4(+) cells in the chamb er fluids compared with blood. In contrast, a higher proportion of CD4 (+) T lymphocytes and a lower proportion of CD8(+) T lymphocytes accum ulated in chamber fluids during the late-phase response compared with that present in blood. The vast majority of the recruited T lymphocyte s expressed a memory phenotype (CD45RO(+)) with enhanced percentages o f CD25(+) and HLA-DR(+) cells. Also, these cells had increased levels of very late antigen-4 (CD49d/CD29) and reduced levels of L-selectin c ompared with the same cells in blood. These results demonstrate that a llergen challenge of the skin in patients with allergy leads to the pr eferential accumulation of activated memory T lymphocytes. The mechani sm by which these cells are selectively recruited during cutaneous all ergic inflammation remains to be determined.