THE ROLE OF THE LYMPHATIC SYSTEM AND LYMPHOID CELLS IN THE ESTABLISHMENT OF IMMUNOLOGICAL MEMORY

Abstract

Summary The capacity of lymph nodes to show secondary reactivity has been investigated in sheep and in mice, using Swine Influenza virus and sheep red blood cells as antigens, respectively. Following a primary challenge to the political node of one leg, the node of the contralateral leg becomes primed and reacts with a secondary response to its first direct encounter of the antigen. This secondary reactivity is acquired in an indirect way and is not due to the transfer of antigen from the injection site in the opposite leg. The secondary response that occurs in “indirectly primed” nodes is not as vigorous or as prompt as mat occurring in “directly primed” nodes. This difference is thought to be due to the presence of both “residential” and “circulating” memory cells, the former class of cells being generated and remaining in lymph nodes where antigen becomes localized while the latter are free‐floating cells of lymph and blood. Circulating memory cells are recruited to a lymph node when an antigen is taken up there, but this recruitment does not appear to be a specific phenomenon.