7th International AIDS Conference Florence, Italy — June 16-21, 1991

Int Conf AIDS 1991 Jun 16-21; 7:94 (abstract no. M.A.1011)
Gattegno L, Ramdani A, Jouault T, Saffar L, Gluckman JC; Faculte de Medecine, Paris-Nord, France

OBJECTIVE: To examine whether mannosyl-specific lectins intervene in rgp160 binding to the cell membrane in a CD4-dependent or- independent manner, and to what extent does lectin-mediated enhanced binding of env glycoprotein correspond to modified susceptibility to HIV-1 infection of monocytic cells as compared with lymphoid cells.

METHODS: We investigated the effect of mannosyl-specific lectins, ConA, LCA, PSA and VFA i) on 125Irgp160 binding to CEM, U937 cells and to monocyte-derived-macrophages; ii) on the interaction of viral gp120 and sCD4; and iii) on HIV-1 infectivity for monocytic cells as compared with lymphoid cells.

RESULTS: sCD4 did not interact with a ConA-Sepharose affinity matrix and HIV-1 preincubated with buffer or with ConA bound to sCD4 in a similar manner. When preincubated with rgp160, or the cells, the lectins significantly enhanced rgp160 binding to the cells in a dose-dependent, carbohydrate specific, and CD4 independent manner. Despite lectin-mediated enhanced binding of env glycoproteins, ConA neutralized HIV-1 infectivity for monocytic as well as for lymphoid cells.

CONCLUSION: These results demonstrate that mannosyl-specific lectins i) induce CD4-independent bridge formation between env glycoprotein and CD4+ cells, ii) do not inhibit gp120-CD4 interactions - which demonstrates that gp120 mannosyl residues are not involved; and iii) neutralize HIV-1 infectivity for monocytic as compared with lymphoid cells. Therefore mannosyl-specific lectins behave like neutralizing antibodies that do not interfere with CD4 binding of gp120 but with post-binding events.

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