T H E Distribution of Large Dividing Lymph Node Cells in Syngeneic Recipient Rats after Intravenous Injection* by Claude Griscelli,$,§ M.d., Pierre Vassalli, M.d., And

I t has been shown by Gowans and Knight (1) that when small lymphocytes obtained from rat thoracic duct lymph are injected intravenously into other rats, the ceils rapidly "home" to lymphoid tissue, that is, to the white pulp of the spleen, lymph nodes in all locations, and lymphoid tissue of the gut, including Peyer's patches. There is considerable evidence that this process is physiological, and reflects the continuous recirculation of small lymphocytes from lymphoid tissue to blood via the major lymphatic ducts and then back again to lymphoid tissue. The mechanism for the "homing" has not been thoroughly elucidated, but it appears to depend upon certain sugar-containing receptors on the lymphocyte surface (2, 3); in any case, there is no reason to believe that it depends upon immunologically specific recognition mechanisms. In contrast to the behavior of small lymphocytes, Gowans and Knight (1) found that large lymphocytes from thoracic duct lymph localize principally in the lymphoid tissue of the gut, with a few being found in the spleen, and virtually none in peripheral lymph nodes. They suggested that this selective localization might be due to the fact that most large lymphocytes in the thoracic duct are derived from intestinal lymphoid tissue, where they may have been "sensitized" to antigens commonly found in the gut. If this explanation were correct, it might be expected that large lymphocytes obtained from other lymph nodes would distribute themselves differently within lymphoid tissues after intravenous injection. In the course of studies concerned with the fate of rapidly