SEVERE INVITRO INHIBITION OF ERYTHROPOIESIS AND TRANSIENT STIMULATION OF GRANULOPOIESIS AFTER BONE-MARROW INFECTION WITH 8 DIFFERENT HIV-2 ISOLATES

Objective: To correlate severe anaemia and frequent neutropenia in HIV-2-infected patients with an inhibitory effect on bone-marrow progenitors common to several HIV-2 isolates. Design: The effects of eight HIV-2 isolates on early (BFU-E) and late (CFU-E) erythroid progenitors and on granulomonocytic (CFU-CM) progenitors, produced in long-term bone-marrow cultures (LTBMC), were studied. Methods: Absolute numbers of BFU-E, CFU-E and CFU-GM per culture flask were calculated weekly for each HIV-2-infected LTBMC using semi-solid clonogenic assays, and compared with those obtained in-mock-infected LTBMC. Levels of significance for comparisons were determined by an analysis of variance (ANOVA). Results: Pooled data from 24 series of LTBMC (three series for each HIV-2 isolate) revealed 80 and 100% inhibition of BFU-E and CFU-E on days 6 and 12 of LTBMC, respectively, while transient stimulation of CFU-GM was observed between days 14 and 20 of LTBMC, followed by total inhibition on day 30. Conclusions: These results confirm a direct inhibitory effect of HIV-2 on in vitro haematopoiesis. The similar pattern of erythroid progenitor inhibition obtained from seven out of eight isolates suggests that the inhibitory effect on erythropoiesis is a feature common to a large number of HIV-2 isolates, which correlates with clinical findings.