Flow cytometric analysis of lymphocyte subsets were evaluated in 391 healthy Asian subjects ranging in age from birth to 40 years. Lymphocyte subsets were analysed using specific monoclonal antibodies: CD20 (B cells), CD3 and CD2 (T cells), CD16 and CD56+ (NK cells), CD4/CD3+ (helper‐inducer T cells), CD8/CD3+ (suppressor/cytotoxic T cells), HLA‐DR expression on CD3 and CD25 (Tac) on CD3. The total white cell count, absolute lymphocyte counts, and B cell percentages peaked in infancy and declined steadily with age. Absolute counts of each subset, which were derived from absolute lymphocyte counts, also followed this trend. Increases with age were seen in the NK, T cell (CD2, CD3), and CD8 percentages. Males tended to have higher NK and CD8 percentages than females, and, conversely, females had higher CD3 and CD4 percentages than males. Comparison of our results with studies involving Caucasian subjects indicated higher NK percentages in our Asian population and lower CD4 absolute counts in the males of our population. These results indicate the presence of age, sex, and probable racial differences in lymphocyte subset expression. Our results may serve as reference standards for the Asian population. © 1996 Wiley‐Liss, Inc.

The amyloid precursor protein (APP) of Alzheimer's disease is a transmembrane protein that is cleaved within its extracellular domain, liberating a soluble N-terminal fragment (sAPP alpha). Putative mediators of this process include three members of the ADAM (a disintegrin and metalloprotease) family, ADAM9, ADAM10 and ADAM17/TACE (tumour necrosis factor-alpha converting enzyme). Tumour necrosis factor-alpha protease inhibitor (TAPI-1), an inhibitor of ADAMs, reduced constitutive and muscarinic receptor-stimulated sAPP alpha release in HEK-293 cells stably expressing M3 muscarinic receptors. However, the former was less sensitive to TAPI-1 (IC(50)=8.09 microM) than the latter (IC(50)=3.61 microM), suggesting that these processes may be mediated by different metalloproteases. Constitutive sAPP alpha release was increased several-fold in cells transiently transfected with TACE, and this increase was proportional to TACE expression. In contrast, muscarinic-receptor-activated sAPP alpha release was not altered in TACE transfectants. TACE-dependent constitutive release of co-transfected APP(695) was inhibited by TAPI-1 with an IC(50) of 0.92 microm, a value significantly lower than the IC(50)s for inhibition of either constitutive or receptor-regulated sAPP alpha shedding mediated by endogenous secretases. The results indicate that TACE is capable of catalysing constitutive alpha-secretory cleavage of APP, but it is likely that additional members of the ADAM family mediate endogenous constitutive and receptor-coupled release of sAPP alpha in HEK-293 cells.

Earlier studies have demonstrated a strong association of steroid-responsive nephrotic syndrome (SRNS), atopy, and elevated serum IgE levels. Interleukin (IL-13) gene expression is significantly increased in children with SRNS in relapse. As interferon (IFN)-gamma, IL-13, and IL-4 have regulatory effects on IgE synthesis, we examined the relationship between intracellular cytokine production and serum IgE levels in children with SRNS, in order to further define the reported association with atopy. The median serum IgE levels in nephrotic patients in relapse with (492 U/ml) or without atopy (561 U/ml) were significantly higher than those in remission (221 U/ml, P<0.002 or 90 U/ml, P<0.001, respectively) and non-atopic controls (177 U/ml) (P<0.001). The percentage of CD3+ IL-13-producing cells was significantly higher in nephrotic children in relapse, and correlated with the serum IgE levels during the active phase of the disease (r=0.90, P<0.001). These data suggest that the elevated serum IgE levels during relapses of SRNS were the result of upregulation of IL-13. This probably reflects some common immune activation following various stimuli, rather than a direct association with atopy.

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Wound fluid collected from chronic venous leg ulcers (chronic wound fluid (CWF)) has been shown to inhibit the growth of dermal fibroblasts by interfering with cell-cycle progression from G1 into S phase. Specifically, CWF was shown to downregulate the levels of hyperphosphorylated retinoblastoma tumor-suppressor gene (Rb) and cyclin D1, known to be critical for entering the S phase of the cell cycle. To further elucidate the effects of CWF, a Ras-mediated signaling pathway involving the mitogen-activated protein kinase kinase (MEK), known to modulate the expression of these cell-cycle-regulatory proteins, was examined. Transient transfection of dermal fibroblasts with constitutively active Ras abrogated the growth suppressive effects of CWF on hyperphosphorylated Rb (ppRb) and cyclin D1. In contrast, an MEK inhibitor PD 98059 mimicked the effects of CWF on these cell-cycle-regulatory proteins. Concurrent treatment with PD 98059 and CWF produced additive effects. Taken together, these results suggest that CWF inhibits the growth of dermal fibroblasts at least in part by decreasing the level of active Ras, resulting in decreased levels of ppRb and cyclin D1. Therefore, a Ras-dependent signaling pathway may mediate the growth inhibitory effect of CWF, and reconstitution of Ras activity may overcome this growth inhibitory effect.

The amyloid precursor protein (APP) of Alzheimer's disease is a transmembrane protein that is cleaved within its extracellular domain, liberating a soluble N-terminal fragment (sAPPα). Putative mediators of this process include three members of the ADAM (a disintegrin and metalloprotease) family, ADAM9, ADAM10 and ADAM17/TACE (tumour necrosis factor-α converting enzyme). Tumour necrosis factor-α protease inhibitor (TAPI-1), an inhibitor of ADAMs, reduced constitutive and muscarinic receptor-stimulated sAPPα release in HEK-293 cells stably expressing M3 muscarinic receptors. However, the former was less sensitive to TAPI-1 (IC50 = 8.09μM) than the latter (IC50 = 3.61μM), suggesting that these processes may be mediated by different metalloproteases. Constitutive sAPPα release was increased several-fold in cells transiently transfected with TACE, and this increase was proportional to TACE expression. In contrast, muscarinic-receptor-activated sAPPα release was not altered in TACE transfectants. TACE-dependent constitutive release of co-transfected APP695 was inhibited by TAPI-1 with an IC50 of 0.92μM, a value significantly lower than the IC50s for inhibition of either constitutive or receptor-regulated sAPPα shedding mediated by endogenous secretases. The results indicate that TACE is capable of catalysing constitutive α-secretory cleavage of APP, but it is likely that additional members of the ADAM family mediate endogenous constitutive and receptor-coupled release of sAPPα in HEK-293cells.

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