Abstract
As an initial approach to macrophage (Mϕ) antigen handling, guinea pig Mϕ pulsed with the radiolabeled terpolymer L‐glutamic acid, L‐lysine, L‐tyrosine (GLT) were modified with the cell surface‐specific probe 2,4,6‐trinitrobenzenesulfonic acid either immediately after pulsing (fresh) or 24 h after pulsing (aged); nonidet P‐40 extracts were prepared from these cells and analysis of these extracts with anti‐trinitrophenyl antisera was performed in a quantitative radioimmunoassay. Such experiments indicated that fresh GLT‐pulsed Mϕ contained a pool of intracellular GLT as well as a distinct pool of cell surface GLT. In contrast, aged GLT‐pulsed Mϕ lacked intracellular GLT but expressed GLT on the cell surface. In addition, a pool of cell surface GLT was also detected on Ia−Mϕ and on Mϕ from guinea pigs which were nonres‐ponders to GLT. Thus, this study provides a direct demonstration of the presence of exogenous antigen on the Mϕ cell surface. However, the cell surface expression of GLT does not appear to be an exclusive property expressed by functional Ia+ antigen‐presenting Mϕ.
