Lymphocytes and the Immune Response

Abstract

Marrow LymphopoiesisThe ultimate origin of both BL and TL is the bone marrow. Chromosomally marked marrow cells injected into lethally irradiated hosts proliferate in the thymus as well as in more peripherally located lymphoid structures,^{123 124 125} whereas cells derived from lymph nodes, thymus or thoracic-duct lymph repopulate the spleen and lymph nodes but are rarely identified in the thymus.^{126 , 127} Further observations have revealed that bone-marrow-derived lymphocytes regenerate in the thymus earlier than in the lymph nodes^{123 , 128}; subsequent repopulation of lymph follicles occurs from cells leaving the thymus. It is probable that a blood-thymic "barrier" exists not only for dyes . . .