Antigen specific IgG+
B cells make up a small percentage of the circulating B cell pool. These cells can be identified by their expression of CD19 and IgG as well as a high affinity to their antigen and represent somatically hypermutated post germinal center IgG memory B cells (Klein, 1998
). The presence of such cells in blood correlates in part with serum antibody titers (Crotty, 2003
; Leyendeckers, 1999
; Nanan, 2001
, (Amanna et al., 2007
To determine whether we could identify HIV-gp140 binding B cells in the circulation of individuals with serum titers of anti-HIV antibodies we studied one such individual and an uninfected control. summarizes the neutralization breadth of the serum from the HIV-infected patient. shows that among CD19+IgG+ B cells in the infected individual we found a distinct population of cells that also bound biotinylated gp140. Further, we were unable to detect a significant number of gp140 binding CD19+IgG+ cells in the circulation of an uninfected control ().
Serum Neutralization of CTR203
Gp140 staining of peripheral blood B cells
We conclude that biotin labeled gp140 trimer can be used to identify gp140 binding B cells in the circulation of HIV infected individuals with serum titers of neutralizing antibodies.