Fc-Specific Suppressor T Cells
BALB/c mice bearing IgA-secreting plasmacytomas exhibit large numbers of Thy-1+, Ly-2+ lymphocytes with surface membrane receptors specific for IgA (Ta cells) (1). These lymphocytes have several characteristics of immunoregulatory T cells (2) and develop in response to the high circulating levels of polymeric IgA as evidenced by: a) their failure to develop in mice bearing IgA non-secreting variant plasmacytomas (1) and (b) their occurrence in normal mice infused daily with high concentrations of polymeric IgA (3). When suppressor Ta cells were transferred to orallyimmunized mice the recipient mice exhibited a marked suppression of the IgA component, but not the IgM or IgG components, of an immune response to an orally administered antigen (4). These findings identify an immunoregulatory circuit in which IgA secreting cells are simultaneously effector cells and regulatory cells. Secreted IgA antibody, in addition to its antigen-specific effector function, can provide an inductive signal for the IgA-binding suppressor T cells which in turn can inhibit further IgA secretion. Enhanced expression of IgA receptors on suppressor T cells requires polymeric forms of IgA which suggests that IgA-Fc receptor cross-linking is a necessary step in the induction process. Under physiological conditions it may be that receptor crosslinking is mediated by the polyvalent arrays of Fc determinants that occur in immune complexes.
KeywordsNylon Wool Receptor Crosslinking Surface Membrane Receptor Heavy Chain Class Immunoregulatory Signal
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- 3.Hoover, R.G., Dieckgraefe, B.K. and Lynch, R.G., J. Immunol. 127, 1560, 1982.Google Scholar