Background: Because increased bone marrow lymphopoiesis might contribute to immunologic reconstitution during highly-active antiretroviral therapy (HAART), we examined the effect of HAART on CD34(+) cell subsets in bone marrow from HIV-infected patients.
Materials and methods: In 12 HIV-infected patients, bone marrow and peripheral blood were collected before then 4 and 26 weeks after initiating HAART. Bone marrow in 28 HIV-seronegative controls was also examined. Immunophenotypic analyses of CD34(+) cell subsets in bone marrow were performed by flow cytometry.
Results: Our main findings in bone marrow were: (i) HIV-infected patients had increased proportions of CD34(+)cells expressing T- and B-cell markers before initiating HAART; (ii) in contrast, these patients had decreased proportions of CD34(+) cells expressing myeloid-associated markers; (iii) although HAART induced an increase in peripheral T-cell counts, the percentage of CD34(+)cells expressing T-cell markers tended to decrease during such therapy; (iv) HAART induced a decrease in serum IgG accompanied by a slight decrease in the proportion of CD34(+)cells expressing B-cell markers; (v) in contrast, HAART induced a significant increase in peripheral granulocyte counts, accompanied by a slightly increased proportion of CD34(+) cells expressing myeloid-associated molecules.
Conclusion: Our findings are compatible with an HIV-related block in T-cell differentiation, leading to accumulation of T-cell progenitors in bone marrow, and such a block may be removed by HAART.