High Frequency of Virus-Specific B Lymphocytes in Germinal Centers of Simian-Human Immunodeficiency Virus-Infected Rhesus Monkeys

Abstract

The etiology of the lymphadenopathy and follicular hyperplasia associated with human immunodeficiency virus type 1 (HIV-1) infection has remained unclear. To determine whether the B-lymphocyte expansions characteristic of this syndrome represent polyclonal and virus-specific processes, the antigen specificity of B cells in lymphoid tissues of monkeys infected with simian-human immunodeficiency virus (SHIV) chimeras was assessed using an inverse immunohistochemical assay with biotinylated HIV-1 envelope gp120 (Env) as an antigen probe. Env-binding B cells were found aggregated in lymph node and splenic germinal centers (GCs). Most Env-binding GCs also contained an unstained population of B cells, suggesting the GCs were formed by a polyclonal (oligoclonal) process. By day 42 following infection, Env-binding B cells were present in 19% of all lymph node GCs. Env-binding cells were present in 25% of GCs even during chronic infection. This extraordinarily high frequency of Env-specific B lymphocytes suggests that the expansion of virus-specific B cells may largely account for the follicular hyperplasia in AIDS virus-infected individuals.

Germinal Center Function in the Spleen during Simian HIV Infection in Rhesus Monkeys

“…In previous studies of SHIV-infected rhesus monkeys, we have shown that lymphoid GCs formed during primary and chronic immunodeficiency virus infection include a high frequency of Envspecific B cells (42). In the present report, we extend those studies with an analysis of Ig sequences from Env-binding GCs.…”

“…Subject Mm18284 was infected with SHIV-KB9ct, and subject Mm19941 was infected with SHIV-KB9(Ϫ305). Some immunologic and virologic data from these monkeys have been previously reported (42,45,47). Infection of both animals was confirmed by serologic and virologic assays (45,47).…”

“…at 3 mo (Mm19941) and 9 mo (Mm18284) after SHIV infection. These time point were chosen to assess GC functions during the early stages of chronic infection, at a time when Env-specific GCs are plentiful (42). Pieces of spleen were frozen in Tissue-Tek cryoembedding medium (Fisher Scientific) immediately upon removal, and stored at Ϫ80 o C until use.…”

“…Unreacted biotin was removed by filtration over a ChromaSpin LC-30 column (BD Clontech). Preservation of conformation-dependent epitopes in the biotinylated Env was documented as described (42).…”

Mamu-A*01 Allele-Mediated Attenuation of Disease Progression in Simian-Human Immunodeficiency Virus Infection

“…GCs have been shown to be occupied by virus-specific and nonspecific B cells in SHIV 89.6P infection (20). Thus, the severe loss of proliferating B cells in GCs observed in the Mamu-A‫10ء‬ Ϫ monkeys may have caused the substantial loss of general B-cell immunity that has been documented for HIV-1 and SIV infection (6,22).…”