Characterization of the murine antigenic determinant, designated L3T4a, recognized by monoclonal antibody GK1.5: expression of L3T4a by functional T cell clones appears to correlate primarily with class II MHC antigen-reactivity

Immunol Rev. 1983:74:29-56. doi: 10.1111/j.1600-065x.1983.tb01083.x.


We describe here the properties of mAb GK1.5, which recognizes a cell surface molecule designated L3T4; the determinant on L3T4 recognized by mAb GK1.5 is designated L3T4a. We present evidence here that: i) the expression of L3T4a by murine T cell clones correlates primarily with class II MHC antigen-reactivity; ii) mAb GK1.5 blocks all class II MHC antigen-specific functions (cytolysis, proliferation, release of lymphokines) by murine class II MHC antigen-reactive T cell clones, although there appears to be clonal heterogeneity in the degree to which these functions are blocked by mAb GK1.5; iii) mAb GK1.5 blocks class II MHC antigen-specific release of IL-2 from cloned T cell hybridomas by blocking class II MHC antigen-specific binding; and iv) L3T4 is very similar to the human Leu3/T4 antigen. The properties of mAb GK1.5 (complement fixation, reactivity with all mouse strains tested, profound blocking of all class II MHC antigen-specific functions by murine T cells, usefulness for FACS analyses, and usefulness for immuno-precipitation/SDS-PAGE analyses) make it suitable for investigating both the role of class II MHC antigen-reactive T cells in various immunological phenomena and the mechanistic basis, at the molecular level, of class II MHC antigen-reactivity by murine T cells.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Monoclonal / biosynthesis
  • Antibodies, Monoclonal / immunology*
  • Antibodies, Monoclonal / physiology
  • Antigen-Antibody Reactions
  • Antigens, Ly / immunology*
  • Binding, Competitive
  • Cytotoxicity, Immunologic
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes / analysis
  • Epitopes / immunology*
  • Flow Cytometry
  • Histocompatibility Antigens / classification
  • Histocompatibility Antigens / genetics
  • Histocompatibility Antigens / immunology
  • Humans
  • Hybridomas / immunology
  • Lymphocyte Activation
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Inbred CBA
  • Rats
  • T-Lymphocytes / immunology*


  • Antibodies, Monoclonal
  • Antigens, Ly
  • Epitopes
  • Histocompatibility Antigens