Expression of Bax, Bcl-2, and p53 in progressive multifocal leukoencephalopathy

It has been shown in vitro that IC viral protein can form a complex with wi ld-type p53 protein, which is a key regulator of both cell proliferation an d cell death. Cellular factors, Bar and Bcl-2, are two essential downstream elements involved in p53-dependent apoptosis. To determine whether associa tion of JC virus with p53 protein affects the expression of Bar and Bcl-2 i n viral-infected cells in progressive multifocal leukoencephalopathy (PML), we studied the expression of pax, Bcl-2, and p53 in 14 cases from 13 PML p atients by using paraffin immunohistochemistry. Seven of 13 patients were k nown to be HIV positive. Overexpression of p53 was found in viral-infected oligodendrocytes and some astrocytes in all 14 cases. Intense immunostainin g of Bar was strongly expressed in viral-infected oligodendrocytes and astr ocytes. Bar immunostaining was also found in macrophages in the demyelinati ng lesions. Bcl-2 was not detected in viral-infected glial cells. The expre ssion pattern of Bar positive/Bcl-2 negative in viral-infected glial cells suggests that the oligodendrocyte may be undergoing apoptosis which may in turn contribute to the demyelinating process in PML, The coexpression of p5 3 and Bar in the infected glial cells suggests that p53 detected by immunoh istochemistry may still maintain its wild-type function.