Muto S, Vĕtvicka V, Ross G D
Department of Microbiology and Immunology, School of Medicine, University of Louisville, Kentucky 40292.
J Clin Immunol. 1993 May;13(3):175-84. doi: 10.1007/BF00919970.
CR3 (CD11b/CD18) functions both as an iC3b-receptor and as an adhesion molecule for cellular ligands such as ICAM-1. Although CR3 has been well characterized on phagocytic cells, much less is known about CR3 on lymphocytes. In this study, the expression of CR3 was examined on resting and stimulated B, T, and natural killer (NK) cells by three-color flow cytometry. Biotinylated anti-CR3 mAb and streptavidin-FITC were used in combination with anti-CD3 mAb conjugated with peridinin chlorophyll-alpha protein (PerCP) and phycoerythrin-labeled mAbs to CD4, CD8, CD19, or CD56. Among resting lymphocytes, CR3 was expressed on nearly all NK cells (CD56+CD3-), 1% of CD4+CD3+ helper T cells, 7% of CD8+CD3+ cytotoxic T cells, and 20% of B cells (CD19+). Among the 5% of T cells (CD3+) expressing CR3, the majority was CD56+. Incubation of PBMC for 30 min with PMA induced a three- to fivefold increase in CR3 expression on NK cells and a twofold increase on T cells but did not change the expression of CR3 on B cells. This effect of PMA was not blocked by the presence of cycloheximide, suggesting the presence of cytoplasmic (granule) stores of CR3 in these lymphoid cells resembling those previously reported in neutrophils and monocytes. When PBMC were incubated with rIFN-alpha, rIL-2, beta-glucan, or high concentrations of LPS, expression of CR3 on NK cells increased significantly, but > or = 4 hr of stimulation was required. Other cytokines (rIFN-gamma, rIL-1, rIL-4, rIL-6, TNF-alpha) and rC5a had no significant effect on CR3 expression. Among NK cells, both the CD56bright and the CD56dim cells expressed CR3, and the expression of CR3 on both of these NK cell subsets was increased in a similar manner by PMA. However, rIL-2 stimulated a greater increase in CR3 expression on CD56bright cells than on CD56dim cells. These studies suggest that CR3 expressed by NK cells or cytotoxic T cells resembles phagocyte CR3 in that cellular activation stimulates increased surface expression of CR3 derived from cytoplasmic reserves of the receptor.
补体受体3（CR3，CD11b/CD18）既作为iC3b受体，又作为细胞配体（如细胞间黏附分子-1，ICAM-1）的黏附分子发挥作用。尽管CR3在吞噬细胞上已得到充分表征，但关于淋巴细胞上的CR3却知之甚少。在本研究中，通过三色流式细胞术检测了静息和活化的B细胞、T细胞及自然杀伤（NK）细胞上CR3的表达情况。生物素化抗CR3单克隆抗体和链霉亲和素-FITC与结合了多甲藻叶绿素蛋白（PerCP）的抗CD3单克隆抗体以及藻红蛋白标记的抗CD4、抗CD8、抗CD19或抗CD56单克隆抗体联合使用。在静息淋巴细胞中，几乎所有NK细胞（CD56⁺CD3⁻）、1%的CD4⁺CD3⁺辅助性T细胞、7%的CD8⁺CD3⁺细胞毒性T细胞以及20%的B细胞（CD19⁺）表达CR3。在表达CR3的5%的T细胞（CD3⁺）中，大多数为CD56⁺。用佛波酯（PMA）孵育外周血单个核细胞（PBMC）30分钟可使NK细胞上CR3的表达增加3至5倍，T细胞上增加2倍，但对B细胞上CR3的表达无影响。PMA的这种作用不受放线菌酮存在的阻断，提示这些淋巴细胞中存在CR3的胞质（颗粒）储存，类似于先前在中性粒细胞和单核细胞中报道的情况。当PBMC与重组干扰素-α（rIFN-α）、重组白细胞介素-2（rIL-2）、β-葡聚糖或高浓度脂多糖（LPS）孵育时，NK细胞上CR3的表达显著增加，但需要≥4小时的刺激。其他细胞因子（rIFN-γ、rIL-1、rIL-4、rIL-6、肿瘤坏死因子-α）和重组C5a对CR3的表达无显著影响。在NK细胞中，CD56bright和CD56dim细胞均表达CR3，PMA以类似方式增加了这两种NK细胞亚群上CR3的表达。然而，rIL-2刺激CD56bright细胞上CR3表达的增加幅度大于CD56dim细胞。这些研究表明，NK细胞或细胞毒性T细胞表达的CR3类似于吞噬细胞CR3，即细胞活化刺激了源自受体胞质储备的CR3表面表达增加。
