Feline lymphoid tissues engrafted into scid mice maintain morphologic structure and produce feline immunoglobulin.

To adapt the feline immune system to a small laboratory animal host, severe combined immunodeficient (scid) mice were engrafted with neonatal feline lymphoid tissues, including lymph node, thymus, spleen, and bone marrow. Lymph node and thymus tissue were implanted subcutaneously within the mammary fat pad, and a single-cell suspension of spleen, thymus, and bone marrow was inoculated intraperitoneally (IP). Seven groups of mice (three mice per group) were engrafted on day 0, and members of one group were euthanatized weekly from 2 to 8 weeks after engraftment. For each mouse, graft morphology was evaluated by light microscopy, feline DNA was detected in peripheral blood by polymerase chain reaction (PCR) amplification of feline-specific DNA sequences, and serum IgG concentration was measured by ELISA. Ten of 13 feline grafts evaluated histologically between 3 and 8 weeks after engraftment contained large focal aggregates of lymphocytes bordered by plasma cells. Of 14 thymus grafts evaluated histologically during the same period, 5 were characterized by dense accumulations of small lymphocytes surrounding thymic epithelial cells. Two of these thymus grafts were indistinguishable from age-matched feline thymus. At 2 weeks after engraftment, feline lymph node and thymus contained extensive central necrosis bordered by a narrow zone of lymphocytes and small-caliber blood vessels.(ABSTRACT TRUNCATED AT 250 WORDS)