Lymphocyte migration into collagen gels: role of lymph

In the present investigation we found that the presence of lymph within a 3-D collagen gel potentiates the invasion of mature recirculating lymphocytes into the gel. Preferential accumulation of lymphocytes in lymph-containing gels follows the same rules that apply for both in vitro lymphocyte adhesion to high endothelial venules of frozen sections of the lymph nodes and in vivo lymph node entry of lymphocytes. Furthermore, the results obtained suggest that lymph is chemotactic for lymphocytes. This chemoattractant activity of lymph could be assigned mainly to a protein fraction precipitating in the range of 40-60% concentration of ammonium sulphate. The biological significance of these findings for the selective process of lymphocyte emigration from blood to lymph, across the parenchyma of the nodes, is discussed.