AEGiS-11IAC: Mechanisms of opsonized-HIV entry in normal B lymphocytes.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Mechanisms of opsonized-HIV entry in normal B lymphocytes.

Int Conf AIDS 1996 Jul 7-12; 11:57 (abstract no. Mo.A.1009)
Legendre C, Gras G, Krzysiek R, Galanaud P, Richard Y, Dormont D; Service de Neurovirologie, IPSC, CEA and CRSSA, Fontenay aux Roses, France. Fax: (33 1) 46 54 77 26. E-mail: gras@dsv-idf.cea.fr.

OBJECTIVE: To determine the respective contributions of CD4, and complement receptors, to opsonized HIV entry into normal B lymphocytes.

METHODS: Normal tonsil B lymphocytes, in vitro stimulated or not, were used as target cells for infection by antibody and complement-opsonized HIV-1/LAI. The effect of CD4-HSA, and that of monoclonal antibodies to CD4, complement receptors type 1 (CR1/CD35) and 2 (CR2/CD21) on virus replication was assessed. Five days post infection, p24 was quantitated in supernatants by ELISA. Inhibition of infection was calculated by comparison of p24 amounts in isotype-matched controls. Before infection, quantitation of CD4, CD21, and CD35 surface expression was assessed by flow cytometry.

RESULTS: Cytometry analyses of B cell immunostainings showed that CD4 is dimly expressed on cell surface in 1 of 3 tested cell batches. CD4 blocking on CD4dim allowed a good inhibition of infection with unstimulated (70%) or PDB-stimulated (85%) B cells. In CD4 negative B cells, inhibition by CD4 mAb was weak (22%) but detectable, demonstrating the presence of the CD4 molecule at infradetectable levels on B lymphocyte surface. Whatever the state of activation, HIV infection of B lymphocytes was decreased by independent or simultaneous blockings of CR1 and CR2 (45-90%). Moreover, blockade of both CD21, CD35 and CD4 molecules showed a very important inhibition of infection (95%). Elsewhere, no additive effect of CD4 monoclonal antibody was observed with CD4- B cells.

CONCLUSION: HIV infection of normal B cells occurs in vitro through two major pathways: the CD4 antigen and the CR1/CR2 complex. These two pathways are independent since a complete inhibition of virus entry requires both CD4 and CD21/CD35 blockade on CD4dim tonsillar B lymphocytes whereas only the latter is critical on CD4 negative tonsillar B cells.

Keywords: AEGIS, HIV, Receptors, Complement 3d, B-Lymphocytes, Antigens, CD4, Receptors, Complement 3b, HIV-1, Complement, Antigens, CD, Receptors, HIV, Receptors, Complement, HIV Infections, Tonsil, HIV Core Protein p24, HIV Envelope Protein gp120, HIV Antibodies, Virus Replication, Antibodies, Monoclonal, Flow Cytometry, Case-Control Studies, CD9 antigen, In Vitro, virology, ICA11

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MoA1009