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

Int Conf AIDS 1991 Jun 16-21; 7:95 (abstract no. M.A.1012)
Patterson S, Gross J, Bedford P, Knight SC; Clinical Research Centre, Harrow, Middlesex, UK

OBJECTIVE: To characterize different populations of peripheral blood DC and investigate their susceptibility to HIV infection.

METHODS: The presence of DR, DQ, CD4, CD3, CD19 and CD14 antigens on DC was assessed by immunogold electron microscopy (EM). Susceptibility to in vitro HIV infection was examined by EM and in situ hybridization to detect viral RNA and DNA. The effect of antibody against CD4 (leu 3a) on infection was also studied.

RESULTS: Two distinct morphological types of DC (1 and 2) were observed, both expressed DR and DQ antigens, low levels of CD4 and lacked markers specific for T (CD3), B (CD19), NK (CD16) and macrophage (CD14) cells. A few cells similar to afferent lymph veiled cells were also seen (type 3 DC). The presence of cells with morphologies intermediate between these types suggests that they represent a differentiation pathway from immature type 1 DC to mature type 3 (veiled) DC. Types 2 and 3 but not type 1 DC were susceptible to HIV infection. By in situ hybridization a higher percentage of DC were positive for viral RNA and DNA than for RNA alone. Infection was blocked by the leu 3a anti CD4 monoclonal antibody. DISCUSSION &

CONCLUSIONS: Morphologically distinct DC that may reflect stages of a developmental pathway were identified. Only those DC considered to be more mature by morphological criteria supported HIV growth. The higher numbers of DC positive for HIV DNA than for RNA suggest that some DC may become latently infected or allow only a low level of virus replication. Despite their ability to bind a vast array of antigens, infection of DC by HIV is mainly dependent on attachment to CD4.

Copyright © 1991 - International AIDS Society (IAS). Reproduction of this abstract (other than one copy for personal reference) must be cleared through the IAS.