Wayne S. Lapp

Learn 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)
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)
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)
To investigate the role of natural killer (NK) cells in the induction and pathogenesis of graft-versus-host (GVH) disease, +/beige (+/bg; normal NK cell activity) and beige/beige (bg/bg; deficient NK cell activity) parental C57BL/6 (B6) lymphoid cells were used to induce GVH reactions in either B6 X C3H/Hej +/bg (+/bgF1) or B6 X C3H/HeJF1 bg/bg (bg/bg F1)(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)
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)
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)
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)
This study presents the sequential morphologic regeneration of graft-vs.-host (GVH)-induced dysplastic thymuses in long-term survivors of GVH reactions. GVH reactions were induced in adult C57BL/6xAF1 (B6AF1) hybrids by injecting 20 x 10(6) A strain parental lymphoid cells (PLC). Starting on day 30 after GVH induction, five to ten animals were randomly(More)
In early embryo loss, the activation of maternal immune effector mechanisms play a critical role in determining the success or failure of a pregnancy. We have previously shown that increased nitric oxide production by decidual macrophages is involved in early embryo loss occurring at day 12 of gestation. In this study, using reverse transcription-PCR and(More)