TABLE 3.

Immunohistochemistry of MS and its variants

Cell type	Immunoreactivitya
	Acute-MS monophasic lesionsb				Diffuse-sclerosis-type lesionsc				Chronic lesions, classic MS
	iNOS	HAM-56	GFAP	NTyr	iNOS	HAM-56	GFAP	NTyr	iNOS	HAM-56	GFAP	NTyr
Monocytes/macrophagesd	+	+	−	+/++e	−	+	−	−	−	−	−	−
Foamy macrophagesf	−	+++	−	−	−	+++	−	−	−	+++	−	−
Astrocytes	+	−	+++	+	+	−	++	+++	−	−	+++	−

^aImmunoreactivities to anti-iNOS, HAM-56, anti-GFAP, and antinitrotyrosine (NTyr) were rated as follows: +, focal (<10% of cells); ++, intermediate; +++, prominent (>50% of cells); −, absent. 

^bLesions from acute rampant monophasic demyelinating illness as observed in biopsy specimen at time of initial clinical presentation; clinicopathologically consistent with diagnosis of acute MS. 

^cLesions from an 11-year-old terminal-stage MS patient, with rapidly progressive, unremitting features resembling acute MS, as seen at time of autopsy. 

^dIncludes cells in the Virchow-Robin (perivascular) spaces, as well as cells infiltrating the white matter. Other mononuclear cells, such as lymphocytes, do not show immunoreactivity with any one of the antibodies employed in this study. 

^eIntralesional staining varies among microscopic fields of a single patient specimen. The relative count of immunoreactive cells is influenced by the lymphocyte-to-monocyte/macrophage ratio that may be increased in the hyperacute phase of acute MS. 

^fMyelin-laden phagocytes in areas of overt demyelination.