Masellis-Smith A, Belch A R, Mant M J, Pilarski L M
Department of Oncology, University of Alberta, Edmonton, Canada.
Cancer Res. 1997 Mar 1;57(5):930-6.
We have earlier described the presence of phenotypically unusual monoclonal B cells within the peripheral blood of multiple myeloma (MM) patients. To determine the biological properties of these B cells as compared to B cells from normal donors, we investigated the potential of CD19+ MM blood B cells to adhere to endothelial cell and bone marrow (BM)-fibroblast monolayers. We find that 30-60% of freshly isolated CD19+ MM blood B cells adhere to endothelial cell monolayers, and 50-80% adhere to BM fibroblast monolayers. The adhesion of MM blood B cells to either monolayer was not increased by in vitro activation, suggesting that these cells were activated in vivo. In contrast, fewer than 10% of CD19+ B cells from peripheral blood of normal donors adhered. Function-blocking monoclonal antibodies (mAbs) were used to determine which adhesion receptors were involved in CD19+ MM blood B cell interaction with BM fibroblasts. mAbs against very late antigen 4, the beta7-integrin subunit, and CD44, but not mAbs against very late antigen 5 and beta1, inhibited adhesion 61, 50, and 30%, respectively. The lack of inhibition with mAbs against beta1 implicates alpha4beta7 but not alpha4beta1 in adhesion of CD19+ MM blood B cells. To determine the alpha4beta7 ligand that mediated MM blood B cell adhesion, mAbs against vascular cellular adhesion molecule 1 and fibronectin, as well as CS1 and RGD peptides, were used as inhibitors. These were unable to reduce the adhesion of CD19+ MM blood B cells to BM fibroblasts, suggesting that fibronectin and vascular cellular adhesion molecule 1 are not involved in adhesion. Also, adhesion of MM blood B cells to mucosal addressin cell adhesion molecule 1-transfected Chinese hamster ovary cells was not enhanced compared to control-transfected Chinese hamster ovary cells, suggesting that mucosal addressin cell adhesion molecule 1 was not promoting adhesion of these cells. These data implicate CD44:HA interactions, as well as alpha4beta7 and an as yet unidentified ligand in the adhesion of in vivo activated MM blood B cell adhesion to BM fibroblasts. The adhesion properties of MM CD19+ B cells distinguishes them from normal B cells. Although the malignant status of these cells is as yet undefined, their adhesion properties implicate MM blood B cells in migratory spread of the disease.
我们之前曾描述过在多发性骨髓瘤（MM）患者外周血中存在表型异常的单克隆B细胞。为了确定这些B细胞与正常供体B细胞相比的生物学特性，我们研究了CD19⁺MM血B细胞黏附于内皮细胞和骨髓（BM）成纤维细胞单层的潜力。我们发现，30%至60%的新鲜分离的CD19⁺MM血B细胞黏附于内皮细胞单层，50%至80%黏附于BM成纤维细胞单层。MM血B细胞与任一单层的黏附在体外激活后并未增加，这表明这些细胞在体内已被激活。相比之下，正常供体外周血中CD19⁺B细胞的黏附率不到10%。使用功能阻断单克隆抗体（mAb）来确定哪些黏附受体参与了CD19⁺MM血B细胞与BM成纤维细胞的相互作用。抗极晚期抗原4、β7整合素亚基和CD44的mAb分别抑制了61%、50%和30%的黏附，但抗极晚期抗原5和β1的mAb则没有抑制作用。抗β1的mAb缺乏抑制作用表明，α4β7而非α4β1参与了CD19⁺MM血B细胞的黏附。为了确定介导MM血B细胞黏附的α4β7配体，使用了抗血管细胞黏附分子1和纤连蛋白的mAb以及CS1和RGD肽作为抑制剂。这些均无法降低CD19⁺MM血B细胞与BM成纤维细胞的黏附，这表明纤连蛋白和血管细胞黏附分子1不参与黏附。此外，与对照转染的中国仓鼠卵巢细胞相比，MM血B细胞与黏膜地址素细胞黏附分子1转染的中国仓鼠卵巢细胞的黏附并未增强，这表明黏膜地址素细胞黏附分子1并未促进这些细胞的黏附。这些数据表明，CD44:透明质酸相互作用以及α4β7和一种尚未确定的配体参与了体内激活的MM血B细胞与BM成纤维细胞的黏附。MM CD19⁺B细胞的黏附特性使其有别于正常B细胞。尽管这些细胞的恶性状态尚未明确，但它们的黏附特性表明MM血B细胞参与了疾病的迁移扩散。
