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 nonresponders 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.
ASJC Scopus subject areas
- Immunology and Allergy