“…However, auto-reactive T cells are also frequently part of the mature immune repertoire of healthy non-MS humans (Burns et al, 1983(Burns et al, , 1986Jingwu et al, 1992;Kerlero de Rosbo et al, 1993;Lindert et al, 1999;Markovic-Plese et al, 1995;Ota et al, 1990) as well as of nonimmunized animals (Schluesener and Wekerle, 1985). Thus, humans often show comparable frequencies of myelin [myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG)]-reactive T cells in their blood, whether they are MS patients or healthy controls (Burns et al, 1983(Burns et al, , 1986Jingwu et al, 1992;Kerlero de Rosbo et al, 1993;Lindert et al, 1999;Markovic-Plese et al, 1995;Ota et al, 1990). These findings suggest that the more important factor in disease development may be activation; that is a greater frequency of activated myelin-reactive cells in MS patients as compared to healthy individuals (Zhang et al, 1994).…”