ABSENCE OF PORCINE INTERFERON-ALPHA SECRETING CELLS IN SEVERE COMBINED IMMUNODEFICIENCY (SCID) MICE INOCULATED WITH PORCINE LEUKOCYTES

A low frequency leukocyte subpopulation, referred to as natural interf eron producing cells (NIPC) is able to produce high amounts of interfe ron alpha (IFN-alpha) following contact with noninfectious viral struc tures. In order to examine the possible leukocytic nature and bone mar row origin of NIPC, severe combined immunodeficiency (SCID) mice were reconstituted with porcine leukocyte populations, including bone marro w cells. At different times after reconstitution, enriched CD4 and CD4 5 positive porcine cells were isolated from various mouse organs and t ested for the presence of porcine NIPC by porcine IFN-alpha specific E LISPOT assay, after in vitro stimulation by UV inactivated transmissib le gastroenteritis virus (TGEV). Although engraftment of porcine cells in SCID mice was shown by now cytometry and by the production of pig immunoglobulins, no IFN-alpha secreting cells could be detected. This result suggests that NIPC do not derive from bone marrow precursor cel ls, or that growth factors needed for in vivo expansion of porcine NIP C were absent in mice. (C) Inra/Elsevier, Paris.