CASP3 and lymphopenia: Thus, it was hypothesized that lymphopenia may be induced by the tissue redistribution of lymphocyte and/or apoptosis through the activation of caspase 3, as IFN-α/β of Type 1 interferons (Type 1 IFN), reported to be related to the trafficking of lymphocytes, was increased following FMDV infection, and the expression of caspase 3 mRNA was upregulated more in PBMC from infected pigs compared to uninfected controls [3,10,11].