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  • Title: Characterization of human helper and suppressor factors with special reference to HLA-DR determinants.
    Author: Lehner T.
    Journal: Immunology; 1983 Apr; 48(4):695-702. PubMed ID: 6187668.
    Abstract:
    Human helper and suppressor cells can be induced entirely in vitro, by culturing lymphocytes with a small or large dose of antigen for 4 days in a Marbrook—Diener system. The corresponding helper or suppressor factor (vitro) can then be released by a second pulse of antigen for 1 day. However, if sensitization has taken place in vivo by a naturally encountered antigen, then helper or suppressor factor (vivo/vitro) can be released by a single pulse of antigen for 1 day from putative in vivo-induced helper or suppressor cells. Helper factorvitro was compared with helper factorvivo/vitro, stimulated by a streptococcal protein antigen derived from Streptococcus mutans. The results of affinity chromatography suggest that both helper factors have an antigen-specific binding site and bind to monoclonal antibodies directed against HLA-DR, MT, β2M and μ chain and a `constant' part on helper factor (HF) determinants. The HFvivo/vitro unlike HFvitro may reflect in vivo-sensitization and thus assay putative in vivo-sensitized antigen specific helper cells. Similarly, suppressor factor vivo/vitro might be a measure of in vivo-induced suppressor cells. Like HF, suppressor factor (SF) has an antigen-specific binding site, HLA-DR, MT and β2M determinants and a `constant' portion of SF. The DR determinants were further characterized by immunoadsorption, using monoclonal antibodies to the α- and β-chain of DR antigen. The results suggest that helper and suppressor factorvivo/vitro express similar Ia determinants. Both expressed an α-chain determinant, recognized by one of the two anti-α-chain antibodies (TAL/1B5), and a β-chain non-polymorphic determinant recognized by one of the four anti-β chain antibodies used (DA6.231). However, both HF and SF derived from DRw6- but not from DR4-typed lymphocytes expressed MT1 (DRw6,1,2) or MT2 (DRw6,3,5,8) determinants. As DR and MT determinants can be expressed on the same molecule, it is possible that both are involved in helper and suppressor activities.
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