Perforin is not co-expressed with granzyme A within... : AIDS (original) (raw)

Basic Science: Original Paper

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

Andersson, Jan; Behbahani, Homira; Lieberman, Judy; Connick, Elizabeth; Landay, Alan; Patterson, Bruce; Sönnerborg, Anders; Loré, Karin; Uccinif, Stefania; Fehniger, Thomas E.

From the aDepartment of Infectious Diseases, Karolinska Institutet, Huddinge University Hospital, Stockholm, Sweden, the bCenter for Blood Research, Harvard Medical School, Boston, Massachusetts, USA, the cDivision of Infectious Diseases, University of Colorado Health Sciences Center, Denver, Colorado, USA, the dDepartment of Immunology/Microbiology, Rush-Presbyterian-St Luke‚s Medical Center and the eDivision of Obstectrics, Gynecology and Medicine, Northwestern University Medical School, Chicago, Illinois, USA and the fDepartment of Experimental Medicine and Pathology, University of Rome La Sapienza, Rome, Italy.

Sponsorship: This work was supported by the National Cancer Institute (grant 2490), the Swedish Medical Research Council (grant 10850), the Bert von Kantzow Foundation and the National Institues for Health (grant AI41536-01).

Requests for reprints to: Dr Jan Andersson, Division of Infectious Diseases, I-63, Huddinge University Hospital, S-141 86 Huddinge, Sweden.

Received: 22 December 1998; revised: 26 April 1999; accepted: 4 May 1999.

Abstract

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.