Abstract In Experiment 1, PBMC were isolated from cows considered healthy or with SCE (n=6/group) on Days 0 (estrus) and 7 (diestrus) of a synchronized estrous cycle. In Experiment 2, on D21 (D0 was defined as the day of Fixed Timed Artificial Insemination (FTAI), cows were evaluated by ultrasonography to assess luteal blood perfusion and PBMC were isolated. On D32, cows were classified into: healthy pregnant (n=7), pregnant with SCE (n=4), healthy non-pregnant (n=8), and non-pregnant with SCE (n=10). Gene expression of ISGs (ISG15, OAS1, MX1 and IFI6) and proinflammatory cytokines (IL1-β, TNF-α and IFN-γ) were determined. Expression of ISG15, MX1, IFI6, TNF-α and IFN-γ did not differ between SCE and healthy cows and between Days 0 and 7. Expression of OAS1 and IL1-β were higher (P=0.02) on Day 7 than Day 0, regardlees of the SCE presence. In Exp.2, ISG15 abundance was 2.5-fold greater (P=0.0008), TNF-α was 2.2-fold greater (P=0.05), and IL1-β tended (P=0.06) to be 2.4-fold higher in pregnant than non-pregnant cows. Luteal blood perfusion was greater (P=0.01) in pregnant animals. In conclusion, OAS1 and IL1-β are transcripts upregulated in PBMC at diestrus, regardless of SCE occurrence. Proinflammatory cytokines are not affected by SCE occurrence, but IL1-β and TNF-α are upregulated in pregnant animals on D21 of pregnancy. ISG15 abundance is a good pregnancy predictor, regardless SCE presence. 1 n=6/group n6group ngroup n 6 group (n=6/group estrus (estrus diestrus (diestrus cycle 2 D D2 D0 (D FTAI, FTAI , (FTAI) D32 into n=7, n7 n=7 (n=7) n=4, n4 n=4 4 (n=4) nonpregnant non n=8, n8 n=8 8 (n=8) n=10. n10 n=10 . 10 (n=10) ISG (ISG15 OAS MX IFI6 IFI IL1β, IL1β ILβ IL1 β, β IL (IL1-β TNFα TNF α IFNγ IFN γ determined P=0.02 P002 P 02 (P=0.02 presence Exp2 Exp Exp.2 ISG1 2.5fold 25fold fold 2.5 5 P=0.0008, P00008 P=0.0008 0008 (P=0.0008) 2.2fold 22fold 2.2 P=0.05, P005 P=0.05 05 (P=0.05) P=0.06 P006 06 (P=0.06 2.4fold 24fold 2.4 P=0.01 P001 01 (P=0.01 conclusion occurrence predictor (FTAI D3 n= (n=7 (n=4 (n=8 n1 n=1 (n=10 (ISG1 P=0.0 P00 (P=0.0 Exp. 5fold 25 2. P0000 P=0.000 000 (P=0.0008 2fold 22 (P=0.05 4fold 24 (n= (n=1 (ISG P=0. P0 (P=0. P000 P=0.00 00 (P=0.000 (n P=0 (P=0 (P=0.00 P= (P= (P