MBP and myeloid sarcoma: Figure 1B demonstrates MBP hydrolysis by anti-MBP and anti-histone IgG preparations. Line C of Figure 1B demonstrates the starting MBP preparation heterogeneity containing mainly 18.5 kDa protein forms. After 10 h of incubation with both IgG preparations, all MBP forms decreased remarkably compared to the control (lane C). These data may potentially indicate that IgGs against histones and MBP from the sera of MS patients could possess a known phenomenon of polyreactivity in complex formation [39,40,41,42] and mutual catalytic cross-reactivity in MBP- and histone hydrolysis.