Activation of HLA-restricted EBV-specific cytotoxic T cells does not require CD4+ (helper) T cells or exogenous cytokines

J Immunol. 1988 Mar 15;140(6):1994-8.

Abstract

MHC-restricted, viral Ag-specific "memory" CTL are thought to play a decisive role in the defense against pathogenic viruses. However, the requirements for activating such CTL remain controversial. In particular, the role of CD4+ helper cells and their soluble products (e.g., IL-2) are uncertain. To approach these questions as they relate to EBV-specific CTL, highly purified CD8+ T cells from healthy EBV-seropositive individuals were cultured with autologous irradiated EBV-transformed B lymphoblastoid cell lines (LCL), in the presence or absence of autologous CD4+ cells or 1 to 10 U/ml purified rIL-2. The results indicate that the induction of CTL requires neither Th cells nor exogenous IL-2. The CTL generated from isolated CD8+ cells were HLA class I restricted as demonstrated by their ability to lyse targets sharing at least one HLA-A or -B Ag with the stimulating autologous LCL. Furthermore, a mAb (W6/32) to a common determinant on HLA class I Ag blocked both the generation and effector phases of killing, whereas an HLA class II directed mAb had no effect. Addition of an IL-2R-specific antibody (anti-Tac) to the culture medium blocked induction of CTL, suggesting that endogenously produced IL-2 plays an obligatory role in this system. Paraformaldehyde fixation of LCL abrogated their ability to function as stimulator cells; however, addition of 2 U/ml exogenous IL-2 to fixed LCL cultured with CD8+ cells allowed for the induction of highly specific CTL. These results indicate that EBV-specific memory CTL can be activated in the absence of CD4+ helper cells or their soluble products, but nonetheless require Ag and IL-2.

Publication types

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

MeSH terms

  • Adult
  • Biological Products / physiology*
  • Cells, Cultured
  • Cytokines
  • HLA Antigens / immunology*
  • Herpesviridae Infections / pathology
  • Herpesvirus 4, Human / immunology*
  • Humans
  • Interleukin-2 / physiology
  • Lymphocyte Activation*
  • Lymphocyte Culture Test, Mixed
  • T-Lymphocytes, Cytotoxic / immunology*
  • T-Lymphocytes, Cytotoxic / pathology
  • T-Lymphocytes, Helper-Inducer / physiology*

Substances

  • Biological Products
  • Cytokines
  • HLA Antigens
  • Interleukin-2