Regions of allelic loss on chromosomes in many tumors of human and some experimental animals are generally considered to harbor tumor-suppressor genes involved in tumorigenesis. Allelotype analyses have greatly improved our under-standing of the molecular mechanism of radiation lymphomagenesis. Previously, we and others found frequent loss of heterozygosity (LOH) on chromosomes 4, 11, 12, 16 and 19 in radiation-induced lymphomas from several F1, hybrid mice. To examine possible contributions of individual tumor-suppressor genes to tumorigenesis in p53 heterozygous deficiency, we investigated the genome-wide distribution and status of LOH in radiation-induced lymphomas from F1 mice with different p53 status. In this study, we found frequent LOH (more than 20%) on chromosomes 4 and 12 and on chromosomes 11, 12, 16 and 19 in radiation-induced lymphomas from (STS/A×MSM/Ms)F1 mice and (STS/A×MSM/Ms)F1-p53KO/+ mice, respectively. Low incidences of LOH (10-20%) were also observed on chromosomes 11 in mice with wild-type p53, and chromosomes 1, 2, 9, 17 and X in p53 heterozygous-deficient mice. The frequency of LOH on chromosomes 9 and 11 increased in the (STS/A×MSM/Ms)F1-p53KO/+ mice. Preferential losses of the STS-derived allele on chromosome 9 and wild-type p53 allele on chromosome 11 were also found in the p53 heterozygous-deficient mice. Thus, the putative tumor-suppressor gene regions responsible for lymphomagenesis might considerably differ due to the p53 status.

Phellinus linteus (PL), one of the immune-regulatory substances, is recognized to play the role in the metabolic process on inflammation and immunity. It has been traditionally used in the oriental medicine to treat inflammatory related disease. The purpose of this study was to evaluate the effects of water extracts of PL on the mesenteric lymph node lymphocytes immune function in the ICR male mice. Control mice received vehicle only. The PL treated mice were administered the respective extract by oral gavages for 4 weeks. IgE concentrations in serum and MLN lymphocytes were significantly lower in PL treated mice than in control mice. PL increased the proportion of CD4+ and CD8+ T cells in MLN lymphocytes. PL significantly decreased Th2 cytokine concentrations and mRNA expression levels in cytokine secretions. Therefore, water extracts of PL modulate inflammatory parameters through regulation of immunoglobulin production resulting from decreased Th2 cytokine secretion and mRNA expression levels and reduce pro-inflammatory cytokine secretion and mRNA expression in MLN lymphocytes.