Figure 3.

Antibody response in Lewis rats injected intraperitoneally (i.p.) with mesenchymal stem cells (MSC). The study included samples from the DMEM and MSC cohorts described in Figure S1C in Supplementary Material. In particular, the MSC cohort was injected i.p. with MSC and followed-up for 15 weeks at the indicated time points in this figure, whereas the control cohort was injected with DMEM i.a. 5 weeks before the 2-week time point. Anti-MSC IgM (A) and IgG (B) antibody reactivity was determined by flow cytometry for all rat sera (0.6% final dilution) collected at baseline and at 2, 7, and 15 weeks after MSC injection. The mean ± SEM of mean FL-1 fluorescence intensity after subtracting the background (reactivity of secondary antibody alone) is shown (n = 5). No significant differences were detected when results of the two cohorts were compared using the Mann–Whitney U test.