The generation and characterization of human monocyte hybridomas

Progressive impairment of monocytic function in HIV-1-infected human macrophage hybridomas

Using human macrophage hybridomas infected with HIV-1, we investigated monocyte function over a 5-week period after HIV-1 infection. Two clones, 63 and 30, were infected with HIV-1IIIB. Infection was documented by RT activity (15 x 10(6) cpm/ml), intracytoplasmic staining with an anti-p24 antibody, in situ hybridization with an HIV-1-specific riboprobe, and electron microscopy showing intracytoplasmic virus. Two weeks after infection, clones 63 and 30 lost expression of all class II antigens (DR, 81.7 vs. 0%; DQ, 15.6 vs. 0%; and DP, 76.9 vs. 0%) while retaining expression of class I (87.4 vs. 84.1%), LFA-1 (82.4 vs. 83.1%), and LFA-3 (79.1 vs. 74.7%) antigens when compared to uninfected cells. When tested for functional integrity, infected but not uninfected clone 63 cells failed to stimulate a tetanus-specific MHC-restricted T cell proliferative response 2 weeks after infection. Cytokine secretion and antigen processing were also perturbed as production of IL-1 was abolished 2 weeks after infection (although IL-6 secretion was augmented) and infected clone 63 cells failed to process exogenous antigen. Last, the viability of T cells cocultured with infected clone 63 was dramatically decreased 35 days after infection (85 vs. 15%). There was no evidence of transmission of HIV-1 to T cells, suggesting a toxic effect of infected clone 63. Taken together, these data suggest that altered macrophage function in our system occurs at multiple levels, which may account for the early immunological defects described in HIV-1 infection.

Persistent infection of human adenovirus type 5 in human monocyte cell lines

Adenovirus infection of human monocyte hybridoma cell lines and the fusion partner U937 was investigated. Adenovirus adsorbed poorly to these cells as well as primary human alveolar macrophages. The virus-binding experiments showed a 100-fold reduction in apparent viral binding to these cells compared to the permissive HeLa cells. Adsorption of adenovirus to these cells could be enhanced by preincubation of adenovirus with its antiserum. Following entry into the cells amplification of adenovirus DNA was detected starting at 2 days postinfection but few mature virus particles were produced. The infected cultures survived the infection and continued to grow for more than a year. In these chronically infected cultures, linear adenovirus DNA persisted up to 200 copies per cell and a small amount of mature virus was produced. Infectious center assay and cell cloning experiments showed that the majority of the cells in the chronically infected cultures harbor adenovirus genome. These results indicate that restriction of replication of human adenovirus type 5 at the late phase results in persistent infection of U937 and the human monocyte hybridoma cell lines.