Distribution and engraftment patterns of human tonsillar mononuclear cells and immunoglobulin-secreting cells in mice with severe combined immunodeficiency: role of the Epstein-Barr virus.

Tonsils seem to be the ideal source of lymphocytes seeding to the mucosa of the respiratory tract. The distribution and engraftment of human lymphocytes injected into mice with severe combined immunodeficiency (SCID) are not well understood. C.B-17 SCID mice were injected intraperitoneally with human tonsillar mononuclear cells (hu-TMC). The hu-TMC-SCID mouse chimeras were subsequently tested for the appearance and distribution of human lymphocytes tagged with H33342 and immunoglobulin-secreting cells in various systemic and mucosal immunocompetent tissues. This was done by fluorescence microscopy of tissue sections for cells supravitally stained before transfer and by an enzyme-linked immunospot assay using cells isolated from murine organs. Most importantly, engraftment of hu-TMC proved to be dependent on the presence of anti-Epstein-Barr virus (EBV) antibody in the donor. hu-TMC engrafted, in decreasing numbers, in the following systemic organs: peritoneal cavity, liver, spleen and bone marrow. Among mucosal tissues tested, hu-TMC were seen in lungs, but not in the intestines. The engraftment of hu-TMC in the lung was more extensive than that in the spleen. These studies demonstrate that hu-TMC engraft in a variety of murine tissues. The striking preference of hu-TMC for the lungs when compared to intestines suggests selective engraftment among distinct mucosal tissues. The hu-TMC-SCID mouse chimera promises to be a unique animal model to study human-mucosa-associated lymphoid cells and EBV-related lymphomagenesis and B cell tumor progression.