We have presented evidence in this review for the following: (a) Macrophages are likely the first cell infected by HIV. Recovery of HIV from macrophages has been documented in the early stages of infection in which virus isolation in T cells is unsuccessful and detectable levels of antibodies against HIV are absent. (b) Macrophages are major reservoirs for HIV during all stages of infection. Unlike the lytic infection of T cells, HIV-infected macrophages show little or no virus-induced cytopathic effects. HIV-infected macrophages persist in tissue for extended periods of time (months) with large numbers of infectious particles contained within intracytoplasmic vacuoles. (c) Macrophages are a vector for the spread of infection to different tissues within the patient and between individuals. Several studies suggest a "Trojan horse" role for HIV-infected macrophages in the dissemination of infectious particles. The predominant cell in most bodily fluids (alveolar fluid, colostrum, semen, vaginal secretions) is the macrophage. In semen, for example, the numbers of macrophages exceed those of lymphocytes by more than 20-fold. (d) Macrophages are major regulatory cells that control the pace and intensity of disease progression in HIV infection. Macrophage secretory products are implicated in the pathogenesis of CNS disease and in control of viral latency in HIV-infected T cells. This litany of events in which macrophages participate in HIV-infection in humans parallels similar observations in such animal lentivirus infections as visna-maedi or caprine arthritis-encephalitis viruses. HIV interacts with monocytes differently than with T cells. Understanding this interaction may more clearly define both the pathogenesis of HIV disease and strategies for therapeutic intervention.
The efficacy of an oral 8-aminoquinoline (8-[[6-(diethylamino)hexyl]amino]-6-methoxy-4-methylquinoline) (WR6026) in the treatment of 16 patients with kala azar was evaluated. The first 8 patients received therapy for 2 weeks at a dosage of 0.75-1.00 mg/(kg.d); 1 patient was cured, and in regard to the other 7, a 1-logarithm decrease in the number of splenic parasites and clinical improvement were noted. The next 8 patients received therapy for 4 weeks at the same daily dosage (1 mg/[kg.d]); 4 were cured, and for the other 4, 1- to 2-log decreases in the number of parasites and clinical improvement (in regard to weight, liver and spleen size, hemoglobin level, and leukocyte count) were noted. The therapy was associated with minimal toxicity; adverse effects included gastrointestinal distress, headache, and methemoglobinemia. The fact that one-half of the patients were cured indicates that future trials with longer regimens and higher dosages are warranted and should include patients for whom existing treatment methods have failed.
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