Interaction between thymocytes and thymus-derived macrophages. I. Surface components participating in mutual recognition

Incubation of C57BL/6 thymus-derived macrophages (TDMφ) with syngeneic thymocytes resulted in binding of thymocytes to macrophages and rosette formation. Up to 60% of the TDMφ formed rosettes with thymocytes after 6 hr of interaction at 4 °C. Rosette formation of the immature PNA⁺ thymocyte fraction was up to fivefold higher than that of PNA^- and cortisone-resistant thymocytes. Pretreatment of PNA^- thymocytes with neuraminidase enhanced thymocyte binding to macrophages up to sevenfold, whereas a marked reduction of rosette formation was seen following (1) incubation of thymocytes with tunicamycin; (2) incubation of macrophages with 20 mM d-galactose, GLCNaC, or GalNaC; (3) treatment of macrophages or thymocytes with trypsin; (4) treatment of macrophages with anti-1-A^b mAb and its F(ab′)₂ fragment; (5) treatment of thymocytes with anti-Lyt-2.2 mAb; and (6) addition of EDTA and EGTA to the interacted two cell populations.