Reconstitution of lymphocyte subsets in scid mice by transplantation of fetal primordia

A gut-homing, oligoclonal CD4+ T cell population in severe-combined immunodeficient mice expressing a rearranged, transgenic class I-restricted alpha beta T cell receptor

We studied the peripheral T cell compartment of H-2b severe combined immunodeficient (scid) mice that express a transgenic (tg) alpha beta T cell receptor (TcR) specific for the H-Y (male) epitope presented by the H-2 class I Db molecule. Large populations of CD3+ NK1.1-TCR beta T+ T cells were present in spleen, mesenteric lymph nodes, peritoneal cavity, lamina propria and epithelial layer of the small and large intestine of 6- to 10-month-old, male and female tg scid mice. Only low numbers of CD3+ T cells were recovered from inguinal, popliteal, or axillary lymph nodes. We studied CD4+ T cells in these tg scid mice. CD4+ T cells were found in the peritoneal cavity, in the mesenteric lymph nodes and in the intraepithelial layer and lamina propria of the gut. All CD4+ T cells were CD44+ (i.e. showed evidence of antigen-driven differentiation) and expressed the tg V beta 8.2 TcR beta-chain (TcR beta T+). Only few CD4+ T cells expressed the tg V alpha 3+ TcR alpha-chain (TcR alpha T). cDNA was prepared from CD4+ T cells from spleen or mesenteric lymph nodes of individual male and female tg scid mice; sequence analyses of polymerase chain reaction-amplified, endogenous TcR alpha-chain (TcR alpha E) transcripts indicated that > 90% of the TcR alpha E-chain transcripts were in-frame, that the TcR alpha E repertoire in CD4+ T cell populations was oligoclonal, and that the TcR alpha E repertoire was different in individual tg scid mice. Hence, an oligoclonal, leaky CD4+ T cell population is selected in tg scid mice that apparently responds to gut-derived antigens. No inflammatory bowel disease (IBD) was evident in the small or large intestine of 6- to 10-month old tg scid mice. After adoptive transfer of purified CD4+ T cells (10(5) cells per mouse) from tg scid mice into non-tg H-2b scid mice, CD4+ TcR alpha T-beta T+ cells were found in gut tissues of the immunodeficient host. Transplanted scid mice developed clinical and histological signs of IBD. An oligoclonal, gut-homing, memory/effector CD4+ CD44+ TcR beta T+ TcR alpha T-T cell subset from leaky tg scid mice thus has a pathogenic potential when released from the control of TcR beta T+ TcR alpha T+ T cells.

Transfer of CD8+ T cells into SCID mice and activation of memory virus-specific cytotoxic T cells

The requirements for the activation of naive and memory CD8+ cytotoxic T (Tc) cells into effector virus-specific Tc cells after transferring them into SCID mice were investigated. SCID mice reconstituted with splenocytes or purified CD8+ T cells from naive or influenza-immune syngeneic mice and immunized with influenza virus generated effector Tc cells specific for influenza virus-infected target cells in vitro. The kinetics of the response varied between those two populations. The generation of effector Tc cells after transfer of memory CD8+ T cells indicates that there exists no absolute requirement for 'help' in the activation of memory virus-immune T cells. However, under the conditions described here the in vitro immunogenic peptide NPP derived from influenza nucleoprotein is not sufficient to elicit a response in vivo.

Selective reconstitution of T lymphocyte subsets in scid mice

The 'empty' splenic T-cell compartment of young scid mice was partially and selectively reconstituted by low numbers of adoptively transferred congenic (C.B-17, BALB/c) or semi-allogeneic (dm2), but not completely allogeneic (C57BL/6) CD4+ T cells from adult donor mice. Under the same experimental conditions, the CD8+ T-cell compartment of young scid mice could only be reconstituted in scid mice continuously substituted with IL-2. CD4+ T cells engrafted in the spleen of H-2d scid recipients displayed specific, anti-Ad-associated proliferative reactivity. (Semi)allogeneic CD8+ T cells engrafted in spleens of scid recipients showed no anti-host H-2 class I-associated cytotoxic reactivity, i.e., this T-cell compartment was specifically tolerized against host (allo)antigens. Reconstitution of lymph nodes was not observed following transplantation of purified CD4+ or CD8+ T cells. Antigen-specific, cellular immune responses could not be induced in scid mice selectively reconstituted with either CD4+ T cells or CD8+ T cells. Partial reconstitution of the CD4+ T-cell compartment was always associated with the appearance of scid-derived, 'endogenous' IgM-producing B cells. Serum antibodies of scid mice with this T cell-induced B-cell leakiness stained an immature subset of congenic thymocytes.