title: The peripheral lymphoid compartment is disrupted in flaky skin mice.
abstract: Flaky skin (fsn) is an autosomal recessive mutation on mouse chromosome 17 that causes severe anaemia, forestomach papillomatosis and a papulosquamous skin disease that resembles psoriasis in humans. In the present paper, it is reported that fsn causes peripheral lymphadenopathy, CD4/CD8 imbalance and hyperresponsiveness to T cell growth factors. Peripheral lymph nodes (PLN) of adult mutant (fsn/fsn) mice were found to contain almost 10-fold more leucocytes than PLN from phenotypically normal littermates (+/fsn or +/+, hereafter referred to as +/?). Analysis of PLN cells using mAbs and flow cytometry revealed that this predominantly lymphoid hyperplasia was characterized by approximately equivalent increases in the numbers of CD3+ T cells and CD19+ B cells. However, expansion within the T cell compartment was non-random, because fsn/fsn PLN had a considerably reduced ratio of CD4+ to CD8+ T cells (1.08 +/- 0.37) compared to +/? PLN (2.47 +/- 0.44, P < 0.0001). In vitro assays of cellular proliferation in response to T and B cell growth factors showed that fsn/fsn PLN cells were hyperresponsive to IL-2, IL-4 and IL-7 when compared with PLN cells from +/? mice. Studies using mesenteric lymph node and peripheral blood cells showed that hyperresponsive cells are widely distributed in fsn/fsn mice. Experiments in newborn mice showed that the lymphoid disturbances caused by fsn are established at least as early as 2 weeks of age, a time that precedes the onset of the earliest clinical skin lesions. These data implicate a role for the fsn gene product in regulating the size and content of the peripheral lymphoid compartment.
authors.affiliation: Genesis Research and Development Corporation Limited, Auckland, New Zealand. n.abernethy@genesis.co.nz
authors.forename: N J
authors.initials: NJ
authors.lastname: Abernethy
authors.forename: C
authors.initials: C
authors.lastname: Hagan
authors.forename: P L
authors.initials: PL
authors.lastname: Tan
authors.forename: N M
authors.initials: NM
authors.lastname: Birchall
authors.forename: J D
authors.initials: JD
authors.lastname: Watson
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001402:B-Lymphocytes / Q000276:immunology; D016516:CD4-CD8 Ratio; D004195:Disease Models, Animal; D005260:Female; D005808:Genes, Recessive; D006801:Humans; D066298:In Vitro Techniques; D008206:Lymphatic Diseases / Q000235:genetics / Q000276:immunology / Q000473:pathology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008817:Mice, Mutant Strains; D010641:Phenotype; D011565:Psoriasis / Q000235:genetics* / Q000276:immunology / Q000473:pathology