To assess whether bovine butyrophilin 1A1 (BTN1A1) peptides can initiate or tolerize against disease in an experimental autoimmune encephalitis (EAE) mouse model.

The etiology of myelin oligodendrocyte glycoprotein (MOG) antibody disease remains unclear, but molecular mimicry with BTN1A1 has been proposed based on sequence homology. Patient MOG-IgG cross-reacts with BTN1A1, and BTN74-90 reportedly induces tolerance in the Dark Agouti rat.

C57BL/6 (B6) mice were immunized with BTN peptides selected by sequence alignment with MOG35-55 (BTN66-79) and MHC II binding prediction (BTN442-456).

For disease induction, Group 1 (n=2) received BTN peptides (200 µg each) + complete Freund’s adjuvant (CFA) + pertussis toxin (PT) on days 0/1. Group 2 controls (n=2) received 200 µg MOG35-55 + CFA/PT.

For tolerization, Group 3 (n=2) was pretreated with BTN + CFA on day -7 before MOG immunization (day 0). Group 4 controls (n=3) were pretreated with AQP4(201-220), which does not induce EAE, before MOG immunization.

Disease was scored by the EAE scale (0-5). Mice were sacrificed on day 21 for spinal cord histology (Luxol fast blue, hematoxylin & eosin) and splenic flow cytometry.

In the induction study, BTN-immunized mice (Group 1) did not develop EAE, whereas MOG35-55 controls (Group 2) reached peak scores of 2.5 and 1.0. Histology confirmed demyelination and infiltration only in controls.

In the tolerization study, Group 3 (BTN-pretreated) mice did not develop disease. Of the three AQP4-pretreated controls (Group 4), one developed EAE (peak 3.0). Flow cytometry revealed no significant differences: mean γδ T cells (% of CD3+ cells) were 0.89% in BTN-pretreated vs. 0.87% in AQP4-pretreated; mean CD4+CD25+ Tregs were 9.75% and 10.15%.

BTN peptides did not induce EAE, suggesting they are insufficient to trigger disease. BTN pretreatment before MOG exposure showed a trend toward reduced disease, consistent with tolerization, but larger cohorts are needed to confirm these effects.