Fig.(6). (gp120). Immunohistochemical demonstration of HIV-1 antigens in frontal lobe neurons of the patient #5 with HAD (the results of staining in patients #1-4 were comparable). (a) Positive neuronal gp120 staining (anti-gp120 (ID6) (brown) and anti-MAP2 (red), 40x). (b) Positive gp120 staining of neurons and negative staining of astrocytes (anti-gp120 (ID6) (brown) and anti-GFAP (red), 40x). (c) Positive gp120 staining of neurons (anti-gp120 (ID6) absorbed with the negative phage 2.13, 100x). (d) Negative gp120 staining of neurons (anti-gp120 (ID6) absorbed with the positive phage 3.3, 100x).