LONG-TERM LYMPHOID RECONSTITUTION OF SCID MICE SUGGESTS SELF-RENEWINGB-CELL AND T-CELL POPULATIONS IN PERIPHERAL AND MUCOSAL TISSUES

Peyer's patch, peripheral lymph node, and mesenteric lymph node cells were transferred to immunodeficient SCID mice to assess the long-term (150-300 days) potential of these cells to repopulate the host's immun e system. Results demonstrate that, irrespective of donor population, total serum Ig and isotype distribution appear normal within 4 weeks o f reconstitution and remain at normal levels for up to one year follow ing cell transfer. At the cellular level, each donor population recons titutes splenic T and B cell compartments in a progressive and quantit atively indistinguishable manner. Immunohistological analyses of recon stituted mice indicate that, although some qualitative differences are evident, normal splenic composition and architecture are observed. In contrast, gut reconstitution varies significantly with donor populati on. Peyer's patch cells yield normal-appearing gut tissue with extensi ve infiltration of the lamina propria and intraepithelial compartments by T cells and IgA-secreting plasma cells. Peripheral lymph node cell s give rise to T cells found almost exclusively in the lamina propria, while IgA secreting plasma cells are rarely detected. The course and extent of reconstitution further suggest that all donor populations co ntain long-lived T and B cells as well as self-renewing lymphocytes ca pable of extensive expansion. This latter observation has potentially important implications for both transplantation biology and gene thera py applications.