AIDS RESEARCH AND HUMAN RETROVIRUSES Volume 16, Number 15, 2000, pp. 1539–1549 Mary Ann Liebert, Inc. Overexpression of Lymphocytic GD3 Ganglioside and Presence of Anti-GD3 Antibodies in Patients with HIV Infection ROBERTA MISASI, 1 MAURIZIO SORICE, 1 TINA GAROFALO, 1 TAMARA GRIGGI, 1 ANNA MARIA GIAMMARIOLI, 2 GABRIELLA D’ETTORRE, 3 VINCENZO VULLO, 3 GIUSEPPE M. PONTIERI, 1 WALTER MALORNI, 2 and ANTONIO PAVAN 4 ABSTRACT This study was undertaken to analyze the role of disialoganglioside GD3 in HIV infection and disease pro- gression. We report here the results obtained by both ex vivo and in vitro experiments on (1) surface and cy- toplasmic expression and distribution of GD3 in HIV-infected cells, (2) the presence of anti-GD3 antibodies in sera of patients with HIV infection in various stages of the disease, and (3) the association of GD3 expres- sion with HIV-related apoptotic events. GD3 expression was determined by high-performance thin-layer chro- matography (HPTLC) and lipid-bound sialic acid and by static and flow cytometric analyses in peripheral blood lymphocytes from 22 AIDS patients, 20 anti-HIV Ab 1 asymptomatic subjects, and 25 healthy donors. Results obtained clearly indicated a significantly higher expression of plasma membrane GD3 content in lym- phocytes from HIV-infected patients with respect to healthy controls. These HIV-induced perturbations of glycosphingolipid metabolism could be detected in all stages of the disease, including asymptomatic individ- uals. In addition, a significant percentage of patients showing disease progression displayed in serum samples an increased presence of anti-GD3 antibodies. Interestingly, ex vivo studies of lymphocytes from patients with HIV infection also indicated that GD3 expression is strictly associated with annexin V binding, an early marker of apoptosis. Moreover, cytofluorimetric analysis showed that virtually all anti-p24 Ab-positive cells were also immunolabeled with anti-GD3 antibodies. Accordingly, in vitro studies showed a significant redistribution and increase in GD3 expression in cultured U937 cells chronically infected with HIV-1 with respect to uninfected counterparts. In conclusion, our data clearly indicate that a significant increase in GD3 content in HIV-in- fected lymphocytes can occur and that this GD3 overexpression is paralleled by the presence of anti-GD3 an- tibodies in the plasma of patients. This is the first demonstration that disialoganglioside GD3, independent of the therapeutic schedule employed, can be considered as one of the early markers of HIV infection and can contribute to the early events leading to T cell depletion by apoptosis. 1539 INTRODUCTION G ANGLIOSIDES (sialic acid-containing glycosphingolipids) are ubiquitous constituents of eukaryotic cells. 1 Patterns of ganglioside cell expression depend on the species, cell type, and age of the individual. In human peripheral blood lympho- cytes (PBLs) monosialoganglioside GM3 is the major ganglio- side constituent 2 ; minor gangliosides include sialoparaglobo- side and monosiaoohexosylceramide. Disialoganglioside GD3 is specifically expressed on the surface of a small subset of hu- man peripheral blood T cells, and GD3 carbohydrate structure has been given the cluster designation CDw60, 3 which is in- volved in T cell activation. 4,5 Indeed, activation of T cells re- sults in increased number of GD3-expressing cells, correlated with increased CD45RO expression. 5 Monoclonal antibodies against GD3 increase proliferation, cytotoxicity, and gene ex- 1 Dipartimento di Medicina Sperimentale e Patologia, Università di Roma La Sapienza, 00161 Rome, Italy. 2 Dipartimento di Ultrastrutture, Istituto Superiore di Sanità, 00161 Rome, Italy. 3 Dipartimento di Malattie Infettive e Tropicali, Università di Roma La Sapienza, 00161 Rome, Italy. 4 Dipartimento di Medicina Sperimentale, Università degli Studi di L’Aquila, 67100 L’Aquila, Italy.