期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：4
页码：998-1003
DOI：10.1073/pnas.0306407101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Dendritic cells (DCs) ingest antigens in peripheral tissues and migrate to lymph nodes where they present MHC class II-bound antigen to CD4+ T cells. We used two-photon microscopy to image the single-cell dynamics of interactions between DCs and T cells within intact lymph nodes in the absence of relevant antigen. DCs were fluorescently labeled in vivo by cutaneous injection of alum adjuvant including carboxyfluorescein diacetate succinimidyl ester (CFSE). CFSE-positive DCs (CD11c+, CD11b+, and low-to-intermediate CD8+) were observed in draining lymph nodes 24-72 h later. Labeled DCs meandered slowly (2-3 {micro}m{middle dot}min-1) in the T cell zone near B cell follicles but vigorously extended long agile dendrites. Encounters between T cells and DCs arose as T cells moved autonomously along random paths. Moreover, T cells did not accumulate around DCs, and their relative velocities approaching and departing DCs were equivalent, implying that T cells are not attracted toward DCs by chemotactic gradients but rather encounter them by chance. T cell/DC contacts occurred primarily on dendrites at arm's length from the DC soma and typically lasted {approx}3 min, enabling an individual DC to interact with up to 5,000 T cells per hour. We conclude that dynamic DC gesticulation and random T cell motility together enhance the stochastic scanning of the T cell repertoire, thereby enabling rapid initiation of the immune response.
