Brief Definitive Report LYMPHOCYTE HOMING INTO LYMPH NODES: IN VITRO DEMONSTRATION OF THE SELECTIVE AFFINITY OF RECIRCULATING LYMPHOCYTES FOR HIGH-ENDOTHELIAL VENULES*

Reci rcu la t ing lymphocytes e m i g r a t e from the blood into l y m p h nodes v ia a sys t em of special ized venu les which are d i s t ingu i shed by endo the l ium composed of t a l l cells con ta in ing l a rge pa le ves icu la r nucle i and a b u n d a n t cy toplasm. The si te of en t ry is specific for h igh -endo the l i a l venules (HEV) and no m i g r a t i o n of lymphocytes into the t i ssue occurs t h r ough o ther va scu l a r endo the l i a (1-5). The bas is of th is se lec t iv i ty is u n k n o w n a l t hough i t has been sugges ted t h a t lymphocytes have surface receptors which recognize endo the l ium of the specia l ized venules (6, 7). This repor t descr ibes an in vi t ro model developed to s tudy the m e c h a n i s m of lymphocyte homing into l ymph nodes. When m u r i n e lymphocy te suspens ions are l aye red over fixed sect ions of syngeneic l ymph nodes, the cells adhe re specif ical ly to HEV bu t not to o ther vascu la r s t ruc tures . Lymphocy tes ob ta ined from thoracic duct lymph, l ymph nodes, and spleen adhe re to the vas t ma jo r i t y of HEV in each section, whereas t h y m u s and bone m a r r o w are deficient in cells capable of b ind ing to HEV in vitro.