Perforin is not co-expressed with granzyme A within cytotoxic granules in CD8 T lymphocytes present in lymphoid tissue during chronic HIV infection

AIDS. 1999 Jul 30;13(11):1295-303. doi: 10.1097/00002030-199907300-00005.


Background: Residual HIV-1-infected cells are poorly eliminated from lymphoid tissue (LT) reservoirs by effector cytotoxic T lymphocytes (eCTL) despite antiretroviral therapy. Perforin and granzyme A (grA) constitute major effector molecules within eCTL granules that induce apoptosis and lysis of virally infected cells.

Objective: Expression of perforin and grA was studied at the single cell level in LT and blood from 16 patients infected with HIV-1 (stage A1-C) who were not taking antiretroviral therapy.

Method: Immunohistochemical analysis by in situ imaging of cells from blood and LT.

Results: Quantitative in situ imaging showed that perforin-expressing CD8 T cells comprised 0.3-1.5% of total cells within the LT from recent HIV-1 seroconverters, while grA was found in 2.1-7.2% of total cells. However, despite high-level grA upregulation (1.5-4.5% of total cells) compared with that in non-infected individuals (0.4-0.9%), perforin expression remained low (< 0.1% of total cells) (P < 0.02) in LT from patients with chronic HIV-1 infection (stage A2-C). This contrasted with findings in peripheral blood mononuclear cells (PBMC) from the same HIV-1 infected cohort where perforin was detected in 13-31% of all PBMC, which was 10- to 100-fold higher than in lymphoid tissue (P < 0.001); grA was found in 14-32% of total PBMC. Two-colour staining showed that granular expression of perforin and grA was restricted to CD8 T cells in over 90% of total cells in both LT and blood.

Conclusions: These findings indicate that cytotoxic perforin expression is impaired at local sites of HIV replication within lymphoid tissue. Since perforin is required together with grA for granule-mediated cytolysis, the low perforin expression in the LT may limit the ability of eCTL to eliminate HIV-1 infected cells in lymphoid tissue.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • CD4 Lymphocyte Count
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism*
  • Cytoplasmic Granules / metabolism*
  • Granzymes
  • HIV Infections / immunology*
  • HIV-1* / physiology
  • Humans
  • Image Processing, Computer-Assisted
  • Immunohistochemistry
  • Lymph Nodes / immunology
  • Lymphoid Tissue / immunology
  • Membrane Glycoproteins / metabolism*
  • Palatine Tonsil / immunology
  • Perforin
  • Pore Forming Cytotoxic Proteins
  • RNA, Viral / blood
  • Serine Endopeptidases / metabolism*
  • T-Lymphocytes, Cytotoxic / immunology


  • Membrane Glycoproteins
  • Pore Forming Cytotoxic Proteins
  • RNA, Viral
  • Perforin
  • Granzymes
  • Serine Endopeptidases
  • GZMA protein, human