Wayne S. Lapp

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The deregulation of the immune response is a critical component in inflammatory disease. Recent in vitro data show that T-cell protein tyrosine phosphatase (TC-PTP) is a negative regulator of cytokine signaling. Furthermore, tc-ptp(-/-) mice display immune defects and die within 5 weeks of birth. We report here that tc-ptp(-/-) mice develop progressive(More)
In this report we have investigated macrophage (M phi) activity and tumor necrosis factor alpha (TNF-alpha) production during graft-vs.-host disease (GVHD). TNF-alpha production by M phi requires two signals: priming of M phi by interferon followed by triggering of TNF-alpha production and release by lipopolysaccharide (LPS). The state of M phi activation(More)
The GvH reaction resulting from the injection of parental strain cells into adult F1 hybrids suppresses both cell-mediated and humoral immune responses and is dependent on the donor-host combination and the number of parental cells used to induce the GvH reaction. The early suppression is due, at least in part, to the increased number of macrophages and the(More)
We present evidence that tumor necrosis factor alpha (TNF-alpha) is transiently expressed at specific times during embryogenesis in precisely defined areas of the nervous system in two different classes of vertebrates. In murine embryos, TNF-alpha was detected in the brain, neural tube and peripheral mixed spinal nerves. In the chick embryo, TNF-alpha was(More)
In recent years, the T-cell protein tyrosine phosphatase (TC-PTP) has become an important member of the protein-tyrosine phosphatase (PTP) family in two aspects. Firstly, TC-PTP has been reported to act on downstream signalling events initiated by the epidermal growth receptor, suggesting that it may act as an important modulator of receptor tyrosine(More)
The T cell protein tyrosine phosphatase (TC-PTP) is one of the most abundant mammalian tyrosine phosphatases in hematopoietic cells; however, its role in hematopoietic cell function remains unknown. In this report, we investigated the physiological function(s) of TC-PTP by generating TC-PTP-deficient mutant mice. The three genotypes (+/+, +/-, -/-) showed(More)
Certain strains of mice display an increased frequency of fetal resorption, but little is known about the effector mechanisms involved. We have examined the events associated with lipopolysaccharide (LPS)-induced fetal resorption in mice. Administration of 25 micrograms LPS on Day 12 of gestation resulted in the appearance of tumour necrosis factor-alpha(More)
Mild, moderate, and severe graft-versus-host (GVH) reactions were induced in four series of experiments in 71 CBA X A and C57BL/6 X A F1 hybrid mice. At regular intervals post-GVH reaction induction (Days 4-42), the animals were sacrificed, autopsied, and histologically studied. Visceral alterations of GVH reaction were recorded in the spleen, lymph nodes,(More)
The injection of parental strain cells into adrenalectomized (CBA x A)F1 mice induced a graft-versus-host (GVH) reaction which was morphologically characterized by thymus epithelial cell injury but not stress-related thymic involution. Thymocytes from mice undergoing a GVH reaction were studied for their ability to reconstitute allograft reactivity in(More)