Lesley J, Hyman R
Department of Cancer Biology, Salk Institute, San Diego, CA 92186-5800.
Eur J Immunol. 1992 Oct;22(10):2719-23. doi: 10.1002/eji.1830221036.
The hyaluronic acid (HA)-binding function of CD44 expressed on the cell surface of normal hematopoietic cells has been studied by assaying binding of fluoresceinated hyaluronic acid (F1-HA) and adhesion to immobilized HA. As has been observed previously, normal hematopoietic cells from bone marrow and spleen do not constitutively bind HA. A CD44-specific monoclonal antibody, IRAWB 14, which has been shown to rapidly induce HA binding in some CD44+ cell lines, was used to activate the HA-binding function of CD44 in these normal cells. Only splenic T cells were activated by the IRAWB 14 antibody to bind F1-HA. Upon activation, F1-HA binding correlated with the level of CD44 expression. Activation of HA binding allowed splenic T cells to adhere to HA immobilized on plastic and to an endothelial cell line in an HA-dependent manner. BALB/c and AKR/J splenic T cells differ in their level of CD44 expression, and this correlated with differences in their ability to bind HA upon antibody activation. The minor subpopulation of MEL-14- T cells were among the brightest F1-HA-staining cells. We propose, on the basis of these and other results, that there are three states of CD44 function with respect to HA binding: (a) a non-activatable, resting state, which cannot be rapidly activated to bind HA, as seen in most hematopoietic cells; (b) an activatable state, which can be rapidly converted to HA-binding function, in this case by the IRAWB 14 antibody, illustrated by T cells as shown here; and (c) a constitutively active state, which can bind HA without antibody activation, seen in some cell lines.
通过检测荧光素标记的透明质酸（F1-HA）的结合以及与固定化透明质酸的黏附，研究了正常造血细胞表面表达的CD44的透明质酸（HA）结合功能。如先前观察到的，来自骨髓和脾脏的正常造血细胞不会组成性地结合HA。一种CD44特异性单克隆抗体IRAWB 14已被证明能在某些CD44 +细胞系中快速诱导HA结合，该抗体被用于激活这些正常细胞中CD44的HA结合功能。只有脾脏T细胞被IRAWB 14抗体激活以结合F1-HA。激活后，F1-HA结合与CD44表达水平相关。HA结合的激活使脾脏T细胞能够以HA依赖的方式黏附到固定在塑料上的HA以及内皮细胞系上。BALB/c和AKR/J脾脏T细胞在CD44表达水平上存在差异，这与它们在抗体激活后结合HA的能力差异相关。MEL-14 - T细胞的少数亚群是F1-HA染色最亮的细胞之一。基于这些及其他结果，我们提出，就HA结合而言，CD44功能存在三种状态：（a）不可激活的静止状态，如大多数造血细胞所见，不能被快速激活以结合HA；（b）可激活状态，可通过IRAWB 14抗体快速转化为HA结合功能，此处以T细胞为例；（c）组成性激活状态，无需抗体激活即可结合HA，在某些细胞系中可见。
