B cells of the largest Ig variable heavy chain gene (VH) family, VH3, are reportedly decreased in patients with late stage HIV-1 disease. This deficit may contribute to their impaired responses to infections and vaccines. We confirmed that the VH3 family was underrepresented in serum IgM proteins, with a 45% decrease in patients with advanced HIV-1 disease. However, the proportion of VH3 within VH(1–6) IgM mRNA from peripheral B cells did not differ from that of control subjects (mean ± SD, 57.1 ± 9.7 vs 61.1 ± 8.7%). Similarly, within VH(1–6) IgD mRNA, which even more closely represents the unstimulated naive repertoire, the relative expression of VH3 mRNA was comparable in the two groups. Moreover, the frequency of individual genes within the VH3 family for IgD, particularly genes which encode putative HIV-1 gp120 binding sites, also was normal in HIV-1-infected patients. However, VH3 family expression for IgG mRNA was significantly decreased (17%) and VH4 IgG was increased (33%) relative to other VH families in advanced HIV-1-infected patients. Thus, the changes in VH family expression were more readily apparent in previously activated IgG “memory” B cell populations and, likely, in cells actively producing IgM rather than in resting naive cells. The presence of a relatively normal naive VH3 IgM and IgD mRNA repertoire in resting cells supports the prospect that with proper stimulation, particularly in conjunction with effective antiviral therapy, vigorous humoral immune responses to infections and vaccines may be elicited in this high-risk population.

Impaired development of local Ab responses may predispose HIV-1-infected patients to an increased rate, severity, and duration of mucosal infections. We characterized the repertoire of Ig-producing cells in the intestinal effector compartment (the lamina propria) of HIV-1-infected (n = 29) and seronegative control (n = 27) subjects. The density of Ig-producing cells per area was similar in both groups. However, the proportions of IgA-producing cells were lower in both the duodenum and colon from HIV-1-infected patients compared with those of control subjects (p < 0.05), with compensatory increases in IgG-producing cells in the colon and IgM-producing cells in the duodenum. Similarly, among Abs in the lumen the proportions of IgA were also decreased and the proportions of IgG were increased among HIV-1-infected patients. On a molecular level, VH gene repertoire analyses by RT-PCR revealed comparable proportions of the VH3 family among duodenal IgA transcripts (50–53%) from both groups. VH3 expression was decreased only for IgM among patients with advanced HIV-1 disease (n = 6) compared with that of control subjects (n = 8) (48 ± 8 vs 62 ± 13%; p < 0.01). Moreover, the frequencies of individual IgM and IgA VH3 genes were comparable in each group, including rates of putative HIV-1 gp120-binding VH3 genes (V3-23, V3-30, V3-30/3-30.5). We conclude that, despite a decrement in local IgA producing cells, the density and molecular VH repertoire of mucosal plasma cells are relatively intact among patients with HIV-1 infection. These data suggest that HIV-1-infected patients use functional regulatory mechanisms to provide sufficient VH diversity and effective induction and differentiation of mucosal B cells.

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