Effect of human recombinant IL-2 on murine macrophage precursors. Involvement of a receptor distinct from the p55 (Tac) protein.
Homogeneous populations of bone marrow-derived murine macrophage precursors are able to respond to human rIL-2. A prolonged exposure to the lymphokine results in proliferation and in the final differentiation of macrophage precursors to mature macrophages, as shown by follow-up of the antigenic profile by means of cytofluorograph analysis. The frequency of the IL-2-responding cells was 1/48 as determined by limiting dilution analysis, and no cell death was evidenced in soft agar cultures. An analysis of the IL-2-binding sites conducted on bone marrow-derived macrophage precursors revealed the presence of 4000 binding sites with intermediate affinity (Kd approximately 3 x 10(-9)). Bone marrow-derived macrophage precursors did not react, even after prolonged culture in IL-2-conditioned media, with mAb recognizing the binding site (AMT-13, 3C7) or a binding site-associate molecule (7D4) of a Mr 50,000 to 60,000 component of the IL-2R expressed by the IL-2-dependent T cell line CTLL-2. Cross-linking studies showed the presence of a single binding protein, with an apparent Mr of 70,000. Macrophage precursors also proved able to internalize human rIL-2 within the first 20 min of incubation at 37 degrees C. The implications of these findings are discussed.
Baccarini
M
M
Department of Immunobiology, Fraunhofer-Institut für Toxikologie und Aerosolforschung, Hannover, FRG.
Schwinzer
R
R
Lohmann-Matthes
M L
ML
D000818:Animals; D000911:Antibodies, Monoclonal; D001853:Bone Marrow; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003432:Cross-Linking Reagents; D003470:Culture Media; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015375:Receptors, Interleukin-2 / Q000276:immunology; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology*; D013194:Staining and Labeling; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D003470:Culture Media; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins