Evidence of B cell clonal expansion in HIV type 1-infected patients

HIV-1 infection results in a gradual decrease in CD4(+) T cell counts and p rogressive immune deficiency. Increased T cell turnover in HIV-1-infected p atients, which can be interpreted as T cell clonal expansion, has been thou ght to be relevant to its pathogenesis. To investigate whether B cell clona l expansion also occurs in HIV-1-infected patients, we examined the express ed V(H)DJ(H) gene sequences of peripheral B cells in HIV-1-infected patient s with hypergammaglobulinemia. Identical V(H)DJ(H) gene rearrangements with additional nucleotide differences in V-H genes were analyzed as a marker o f clonally related B cells. From healthy individuals and HIV-1-uninfected p atients with hypergammaglobulinemia, clonally related B cells were detected in none of 10 (0%) and 2 of 10 (20%), respectively. No clonally related B cells were detected in any of the nine HIV-1-infected patients with detecta ble viral loads and normal Ig levels (0%). In contrast, from 9 of 14 HIV-1- infected patients with hypergammaglobulinemia (64%), clonally related B cel ls were detected. In addition, no HIV-1-infected patients who exhibited nor mal Ig levels after antiretroviral therapy had clonally related B cells. Th ese findings suggest that B cell clonal expansion is present in HIV-1-infec ted patients with hypergammaglobulinemia.