Patterns of costimulation of T cell clones by cross-linking CD3, CD4/CD8, and class I MHC molecules

J Immunol. 1989 Jun 15;142(12):4201-12.


The ability of mAb to class I MHC molecules, CD3, or CD4/CD8 to stimulate human T cell clones alone or in combination was examined. Cross-linking each of these surface Ag with appropriate mAb and goat anti-mouse Ig (GaMIg) resulted in a unique pattern of increase in intracellular free calcium ([Ca2+]i) and different degrees of functional activation. Cross-linking class I MHC molecules provided the most effective stimulus of IL-2 production and proliferation. Cross-linking more than one surface Ag induced a compound calcium signal with characteristics of each individual response. Cross-linking CD3 + HLA-A,B,C caused a rapid and prolonged increase in [Ca2+]i and synergistically increased IL-2 production and proliferation of all clones. Cross-linking CD3 + CD4/CD8 also generated a compound calcium signal and increased IL-2 production and DNA synthesis. Purposeful inclusion of CD3 was not required for costimulation as cross-linking HLA-A,B,C + CD4/CD8 also increased [Ca2+]i, IL-2 production, and proliferation. Cross-linking three surface Ag, CD3 + HLA-A,B,C + CD4/CD8, resulted in the greatest initial and sustained [Ca2+]i, IL-2 production, and DNA synthesis. Although there was a tendency for the various stimuli to increase both [Ca2+]i and functional responsiveness, neither the magnitude nor duration of the increased [Ca2+]i correlated with the amount of IL-2 produced or the ultimate proliferative response. To determine whether costimulation required that the various surface molecules were cross-linked together, experiments were carried out using isotype specific secondary antibodies. Augmentation of [Ca2+]i and costimulation of functional responses were noted when class I MHC molecules were cross-linked and CD3 was bound, but not cross-linked. Similarly, costimulation through CD3 and CD4/CD8 was observed when CD4/CD8 was cross-linked and the CD3 complex was engaged by an anti-CD3 mAb which was not further cross-linked. In contrast, costimulation by class I MHC molecules and CD4/CD8 was only observed when these molecules were cross-linked together. These data demonstrate that cross-linking class I MHC determinants or CD4/CD8 provides a direct signal to T cell clones that can be enhanced when CD3 is independently engaged. The results also indicate that T cell clones can be stimulated without engaging CD3 by the combination of signals delivered via class I MHC molecules and CD4/CD8, but only when these determinants were cross-linked together. These studies have demonstrated that these cell surface molecules differ in their capacity to deliver activation signals to T cell clones and also exhibit unique patterns of positive cooperativity in signaling potential.

Publication types

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

MeSH terms

  • Adjuvants, Immunologic / physiology
  • Animals
  • Antibodies, Monoclonal / physiology
  • Antigens, Differentiation, T-Lymphocyte / immunology
  • Antigens, Differentiation, T-Lymphocyte / metabolism*
  • CD3 Complex
  • Calcium / metabolism
  • Clone Cells / immunology
  • Clone Cells / metabolism
  • Cross-Linking Reagents*
  • Epitopes / immunology
  • HLA-A Antigens / immunology
  • HLA-A Antigens / metabolism
  • HLA-B Antigens / immunology
  • HLA-B Antigens / metabolism
  • HLA-C Antigens / immunology
  • HLA-C Antigens / metabolism
  • Histocompatibility Antigens Class I / immunology
  • Histocompatibility Antigens Class I / metabolism*
  • Humans
  • Interleukin-2 / biosynthesis
  • Lymphocyte Activation*
  • Mice
  • Receptors, Antigen, T-Cell / immunology
  • Receptors, Antigen, T-Cell / metabolism*
  • Signal Transduction
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism*


  • Adjuvants, Immunologic
  • Antibodies, Monoclonal
  • Antigens, Differentiation, T-Lymphocyte
  • CD3 Complex
  • Cross-Linking Reagents
  • Epitopes
  • HLA-A Antigens
  • HLA-B Antigens
  • HLA-C Antigens
  • Histocompatibility Antigens Class I
  • Interleukin-2
  • Receptors, Antigen, T-Cell
  • Calcium