Payne N R, Horwitz M A
Department of Pediatrics, UCLA School of Medicine 90024.
J Exp Med. 1987 Nov 1;166(5):1377-89. doi: 10.1084/jem.166.5.1377.
We have examined receptors mediating phagocytosis of the intracellular bacterial pathogen, Legionella pneumophila. Three mAbs against the type 3 complement receptor (CR3), which recognizes C3bi, inhibit adherence of L. pneumophila to monocytes by 64 +/- 8% to 74 +/- 11%. An mAb against the type 1 complement receptor (CR1), which recognizes C3b, inhibits adherence by 68 +/- 1%. mAbs against other monocyte surface antigens do not significantly influence adherence. Monocytes plated on substrates of L. pneumophila membranes modulate their CR1 and CR3 receptors but not Fc receptors; such monocytes bind 70% fewer C3b-coated erythrocytes and 53% fewer C3bi-coated erythrocytes than control monocytes. Adherence of L. pneumophila to monocytes in nonimmune sera is dependent on heat-labile serum opsonins; adherence is markedly reduced in heat-inactivated serum (84% reduction) or buffer alone (97% reduction) compared with fresh serum. mAbs against CR1 and CR3 receptors also inhibit L. pneumophila intracellular multiplication and protect monocyte monolayers from destruction by this bacterium. This study demonstrates that human monocyte complement receptors, CR1 and CR3, mediate phagocytosis of L. pneumophila. These receptors may play a general role in mediating phagocytosis of intracellular pathogens.
我们已经研究了介导细胞内细菌性病原体嗜肺军团菌吞噬作用的受体。三种针对识别C3bi的3型补体受体（CR3）的单克隆抗体，可使嗜肺军团菌对单核细胞的黏附抑制64±8%至74±11%。一种针对识别C3b的1型补体受体（CR1）的单克隆抗体，可使黏附抑制68±1%。针对其他单核细胞表面抗原的单克隆抗体对黏附没有显著影响。接种在嗜肺军团菌膜底物上的单核细胞会调节其CR1和CR3受体，但不会调节Fc受体；与对照单核细胞相比，这类单核细胞结合的C3b包被红细胞减少70%，结合的C3bi包被红细胞减少53%。在非免疫血清中，嗜肺军团菌对单核细胞的黏附依赖于热不稳定的血清调理素；与新鲜血清相比，在热灭活血清（减少84%）或单独缓冲液（减少97%）中，黏附明显减少。针对CR1和CR3受体的单克隆抗体也能抑制嗜肺军团菌在细胞内的增殖，并保护单核细胞单层免受该细菌的破坏。这项研究表明，人类单核细胞补体受体CR1和CR3介导嗜肺军团菌的吞噬作用。这些受体可能在介导细胞内病原体的吞噬作用中发挥普遍作用。
