Modulation of alloreactivity by Mac-1+, -2+, and -3+ macrophages from normal and tumor-bearing hosts: flow cytofluorometrically separated macrophages.
Macrophages (M phi) are multifunctional cells that regulate humoral and cellular immune responses. Our studies of tumor-induced M phi-mediated dysfunction used M phi subsets which were defined by their Mac-1, Mac-2, and Mac-3 surface markers. To measure the accessory activity of M phi for T cell alloreactivity, thioglycollate-elicited peritoneal M phi from normal and tumor-bearing hosts (TBH) were labeled with anti-Mac-1, -2, or -3 antibodies and separated by flow cytofluorometry. The separated Mac-1+, -2+, and -3+ M phi were called sorted M phi, while unseparated M phi were designated unsorted M phi. Both M phi types were added to mixed lymphocyte reaction (MLR) cultures at concentrations ranging from a low of 2% M phi to a high of 20% M phi. The low concentration of unsorted normal host M phi caused a 31% suppression of alloreactivity. Suppression reached 68% when high concentrations of unsorted normal host M phi were added to the MLR cultures. Unsorted TBH M phi reduced alloreactivity by 64% and 86% at low and high concentrations, respectively. When separated into subpopulations, normal host Mac-1+ M phi reduced alloreactivity by 48% and 81% when added at low and high concentrations, respectively. TBH Mac-1+ reduced alloreactivity by 31% and 59% at low and high concentrations, respectively. There were no differences in the suppression caused by normal or TBH Mac-2+ M phi, and by normal or TBH Mac-3+ M phi. Indomethacin treatment did not effect the suppression caused by Mac-1+ M phi, suggesting that proataglandin E2 was not involved. Indomethacin treatment did reduce suppression mediated by Mac-2+, -3+, and unsorted M phi. Mac-2+ M phi dramatically enhanced alloreactivity at low concentrations with normal host Mac-2+ M phi providing greater enhancement of alloreactivity than TBH Mac-2+ M phi. The division of M phi into subpopulations on the basis of Mac antigens suggested that Mac-1+ and -3+ M phi played a major role in immunosuppression in the normal host, while Mac-3+ M phi were more active in TBH immunosuppression. Because no one population of sorted TBH M phi was more suppressive than sorted normal host M phi, we suggest that tumor-induced immunosuppression may involve a network of suppressor M phi.
Askew
D
D
Department of Biology, Microbiology, Virginia Polytechnic Institute, State University, Blacksburg.
Burger
C J
CJ
Elgert
K D
KD
D000818:Animals; D000943:Antigens, Differentiation / Q000276:immunology; D005354:Fibrosarcoma / Q000139:chemically induced / Q000276:immunology*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D037502:Galectin 3; D007108:Immune Tolerance; D007213:Indomethacin / Q000494:pharmacology; D007519:Isoantigens; D007959:Lymphocyte Culture Test, Mixed; D016177:Macrophage-1 Antigen / Q000276:immunology; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010529:Peritoneal Cavity / Q000166:cytology; D013154:Spleen / Q000276:immunology; D013864:Thioglycolates
D000943:Antigens, Differentiation; D037502:Galectin 3; D007519:Isoantigens; D016177:Macrophage-1 Antigen; D013864:Thioglycolates; C036763:monocyte-macrophage differentiation antigen; D007213:Indomethacin