| 描述 | The JY/93 monoclonal antibody specifically recognizes Lyb-2.2 and Lyb-2.3 (CD72 b and c alloantigens, respectively). CD72 is a 45-kDa type-II membrane protein containing a C-type lectin-like domain, an ITIM and ITIM-like sequence in the cytoplasmic tail. Recently, CD72 has been shown to negatively regulate B-cell receptor signaling. Analysis of CD72-deficient mice supports these results and shows that CD72 is involved in B-cell development. CD72-stimulated B cells show a transient association of CD19 with CD72, as well as an increase in Tyr-phosphorylation of CD19. CD72 is reported to be a ligand for CD5,5 although this is controversial. The CD72 alloantigens Lyb-2.1 (originally identified as Ly-m19.2), Lyb-2.2 (originally identified as Ly-32.2), Lyb-2.3, and Lyb-2.4 are encoded by the Cd72[a], Cd72[b], Cd72[c] , and Cd72[d] alleles, respectively. Lyb-2.2 (CD72b) is expressed on B lymphocytes, a subset of peripheral T cells, activated thymocytes, and activated T lymphocytes in A, BALB/c, CBA/H, CBA/N, C3H/He, C57BL, NZB, NZW, PL, and 129 strains. Moreover, expression of CD72b on T cells is dominant in F1 hybrid mice, and its level of expression increases upon activation. Lyb-2.3 (CD72c) is expressed on B cells of AKR, CE, SJL, and other mouse strains. Although staining of a small percentage of splenic T cells has been detected in CD72c mice, northern blot analysis has shown no expression of CD72c in T lymphocytes of these mice. JY/93 mAb does not stain cells from CD72a mice ( e.g ., CBA/J, DBA/2, SWR), and it does not stain resting thymocytes, splenic CD11b-positive cells, or NK cells. Five serological specificities of CD72 alloantigens have been described and the nomenclature CD72.1, CD72.2, CD72.3, CD72.4, and CD72.5 proposed. |
