ENRICHMENT OF CORONAVIRUS-INDUCED INTERFERON-PRODUCING BLOOD LEUKOCYTES INCREASES THE INTERFERON YIELD PER CELL - A STUDY WITH PIG LEUKOCYTES

Porcine peripheral blood mononuclear cells, which secrete IFNalpha in response to a coronavirus, transmissible gastroenteritis virus, were d etected by a filter immunoplaque assay (ELISPOT). IFNalpha-producing c ells (IPC), which are present at a low frequency in the blood, could b e enriched up to 100-fold by sequential depletion of plastic-adherent cells and cell fractionation on metrizamide density gradients. IPC wer e present in the non-adherent low-density cell subpopulation. Cell sel ection experiments using antibody (Ab)-coated immunomagnetic beads rev ealed that porcine IPC could be positively selected by anti-CD4 or -SL A-class-II Ab, but not by anti-CD2 or -CD8 Ab. The estimated IFN yield per IPC was found to increase when IPC were assayed at higher concent rations. These data suggest that IPC represent a unique and distinct c ell population in the blood, which could secrete higher amounts of IFN following its accumulation at a site of viral infection.