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J. Exp. Med.,
Volume 187, Number 2, January 19, 1998 205-216
By


From the * Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford
University, Stanford, California 94305, and the Veterans Affairs Palo Alto Health Care Systems,
Palo Alto, California 94304; and To characterize the adhesion cascade that directs lymphocyte homing to peripheral lymph
nodes (PLNs), we investigated the molecular mechanisms of lymphocyte interactions with the
microvasculature of subiliac lymph nodes. We found that endogenous white blood cells and
adoptively transferred lymph node lymphocytes (LNCs) tethered and rolled in postcapillary
high endothelial venules (HEVs) and to a lesser extent in collecting venules. Similarly, firm arrest occurred nearly exclusively in the paracortical HEVs. Endogenous polymorphonuclear
(PMNs) and mononuclear leukocytes (MNLs) attached and rolled in HEVs at similar frequencies, but only MNLs arrested suggesting that the events downstream of primary rolling interactions critically determine the specificity of lymphocyte recruitment. Antibody inhibition studies revealed that L-selectin was responsible for attachment and rolling of LNCs, and that LFA-1 was essential for sticking. LFA-1-dependent arrest was also abolished by pertussis toxin, implicating a requirement for G
The Center for Blood Research and the Department of Pathology,
Harvard Medical School, Boston, Massachusetts 02115
i
-protein-linked signaling.
4 integrins, which play a critical role
in lymphocyte homing to Peyer's Patches, made no significant contribution to attachment,
rolling, or sticking in resting PLNs. Velocity analysis of interacting LNCs revealed no detectable contribution by LFA-1 to rolling. Taken together, our results suggest that lymphocyte- HEV interactions within PLNs are almost exclusively initiated by L-selectin followed by a G
protein-coupled lymphocyte-specific activation event and activation-induced engagement of
LFA-1. These events constitute a unique adhesion cascade that dictates the specificity of lymphocyte homing to PLNs.
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