In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Porcine blood mononuclear cells (PBMC) were shown to produce interferon-a (IFNa) following incubation with cells infected by a coronavirus, transmissible gastroenteritis virus. Monoclonal antibodies (mAb) with specificities for leukocyte subsets and major histocompatibility complex (MHC) antigens were used to characterize IFNa producer cells. The production of IFNa was found to be a function of non-phagocytic, non-adherent, non-T, non-B, CD4 + (and to a lesser extent CD8 +) MHC-class-II-positive ceils. Furthermore, addition of anti-MHC (class II) mAb during PBMC incubation with virus-infected cells reduced IFN yields, suggesting that masking of these surface antigens alters PBMC responsiveness to IFN induction.
CHARACTERIZATION OF BLOOD MONONUCLEAR CELLS PRODUC- ING IFNa FOLLOWING INDUCTION BY CORONAVIRUS-INFECTED CELLS (PORCINE TRANSMISSIBLE GASTROENTERITIS VIRUS)