Syngeneic Stromal Cells Research Articles

IL-2-Driven Natural Killer Cell Generation: Role of Anti-H-2b Monoclonal Antibodies and Stromal Cells in Controlling Quantitative and Repertoire Changes

To investigate the role of major histocompatibility complex class I and bone marrow stromal cells on in vitro differentiation of natural killer cells, a CD44low/-CD2- population was isolated from mouse bone marrow. This NK-1.1-CD3 LFA-3+B220+ population, when stimulated with IL-2 and co-cultured with supportive syngeneic stromal cells, generated populations of NK-1.1+Ly49A+Ly49C/I+CD3- mature natural killer cells. The effect of anti-H-2b monoclonal antibodies (mAbs) on this phenomenon was assayed. Pre-adhesion of anti-H-2b mAbs to the stromal cells did not exert any effect, whereas when the same mAbs were pre-adhered to progenitors, there was a inhibition of natural killer cell generation that was maximum when the mAbs were added directly to cultures. In addition, the anti-H-2b mAbs did not inhibit the IL-2-induced proliferation of mature natural killer cells. Allogeneic but not H-2b-deficient stromal cells decreased the expression of Ly-49C/I but not Ly49A, thus suggesting that stromal cell haplotypes qualitatively influence the expression of Ly49s repertoire.

Homing and immunogenicity of murine stromal cells transfected with xenogeneic MHC class II genes

Syngeneic (murine) and xenogeneic (canine) marrow-derived stromal cells were injected intravenously into SCID and normal mice to examine the homing pattern and persistence of these cells in vivo. By in situ hybridization, these stromal cells were detectable in the bone marrow cavity and the spleen 21 days after injection. Xenogeneic cells did not persist in normal mice but persisted in SCID mice. Conditioning of the recipients with irradiation or 5-fluorouracil (5-FU) treatment did not alter these results. In addition, syngeneic murine stromal cells were transfected with the genes for canine MHC class II (DRA + DRB) and transplanted into murine recipients to investigate their homing pattern and immunogenicity. These transfected syngeneic stromal cells did also home to marrow and spleen even in normal recipients. However, these cells led to sensitization of the host towards canine antigens as shown by accelerated skin graft rejection and delayed type hypersensitivity (DTH). Thus, immunodeficient (SCID) mice allow for the homing of xenogeneic stromal cells to hemopoietic organs and for prolonged persistence. In immunocompetent (normal) mice, no xenogeneic stromal cells were identified in spleen and marrow, either because of their inability to home or more likely because of immunological rejection. In contrast, syngeneic stromal cells expressing xenogeneic MHC class II genes did home to spleen and marrow and persisted even though the recipient had become sensitized. Their survival may be due to a loss of expression of the transfected gene. Alternatively, the presentation of these xenogeneic gene products in the hemopoietic organs was such that a cytotoxic response was not induced.(ABSTRACT TRUNCATED AT 250 WORDS)