Table 1.

Summary and description of the variables of the study

Donor		Recipients
ELA haplotypes	Target cells	Group	ELA haplotypes	Time-points of sera harvesting	Sera dilution
ZAR07/ZAR08	PBLs1 (control) MSC-naïve (unstimulated) MSC-primed (5 ng/ml TNFα and 5 ng/ml IFNγ for 12 h)	Naïve-mismatched: • Injected with MSC-naïve • ELA-mismatched with donor (0/2 haplotypes shared) • N = 4	ZAR01/ZAR21 ZAR01/ZAR02 ZAR01/ZAR02 ZAR01/ZAR06	T0 = pre-administration of MSCs T1 = 1 week after 1st MSC administration T2 = 3 weeks after 1st MSC administration (just before 2nd administration) T3 = 1 week after 2nd MSC administration T4 = 90 days after 2nd MSC administration	Neat (no dilution) Dilution 1:2 Dilution 1:16
		Primed-halfmatched: • Injected with MSC-primed • ELA-halfmatched with donor (1/2 haplotypes shared) • N = 3	ZAR07a/ZAR09 ZAR07/ZAR10 ZAR07/ZAR14
		Primed-mismatched: • Injected with MSC-primed • ELA-mismatched with donor (0/2 haplotypes shared) • N = 3	ZAR03/ZAR12 ZAR03/ZAR16 ZAR09/ZAR13

ELA haplotypes of the donor selected and type of target cells; groups of recipients according to MSCs received and their haplotypes (when possible, sharing of one haplotype among recipients was used as criteria to select more homogeneous groups: naïve-mismatched recipients all shared the haplotype ZAR01; primed-halfmatched recipients shared the haplotype ZAR07 among them and with the donor - one of the recipients presented the variation ZAR07a; two primed-mismatched recipients shared the haplotype ZAR03 and the other one did not share any haplotype); time-points at which sera was collected from recipients and sera dilutions assessed. MSCs mesenchymal stem cells, ELA equine leukocyte antigen, TNFα tumor necrosis factor alpha, IFNɣ interferon gamma, T time, PBL peripheral blood lymphocyte. ¹PBLs were obtained from a different horse but with the same ELA haplotypes than the donor selected