The CXCL12/CXCR4 signaling exerts a dominant role in promoting hematopoietic stem and progenitor cell (HSPC) retention and quiescence in bone marrow. Gain-of-function CXCR4 mutations that affect homologous desensitization of the receptor have been reported in the WHIM Syndrome (WS), a rare immunodeficiency characterized by lymphopenia. The mechanisms underpinning this remain obscure. Using a mo...

Lymphopenia-induced proliferation (LIP) is a proliferative program initiated in response to T cell insufficiency caused by acute or chronic immunodepletion. Studies of lymphopenic mice have demonstrated that the cytokine IL-7 and TCR signaling are critical for LIP. We examined how these two factors impact T cell proliferation following transfer into moderately lymphopenic mice. In this study, w...

Normal subjects given 60 mg of prednisone orally at 8:00 a.m. developed a transient lymphopenia at 2:00 p.m. To define the populations of lymphocytes affected the number and type of lymphocytes in the peripheral blood were assayed. "Late" and "early" spontaneous sheep red blood cell rosettes were used as markers for thymus-derived (T) lymphocytes and one of its subpopulations, respectively. Rec...

OBJECTIVE To assess immunologically relevant outcomes in a cohort of rheumatoid arthritis (RA) patients with prolonged therapy-induced lymphopenia. METHODS Morbidity (infection or malignancy) and mortality were assessed in 53 RA patients who were treated with the lymphocytotoxic monoclonal antibody alemtuzumab between 1991 and 1994. Data were obtained by interview, medical record review, and ...

CD4+CD25+Foxp3+ Tregs have an indispensable role in the maintenance of tolerance after allogeneic HSC transplantation (HSCT). Patients with chronic graft-versus-host disease (GVHD) have fewer circulating Tregs, but the mechanisms that lead to this deficiency of Tregs after HSCT are not known. Here, we analyzed reconstitution of Tregs and conventional CD4+ T cells (Tcons) in patients who underwe...

Classical swine fever (CSF) severity is dependent on the virulence of the CSF virus (CSFV) strain. The earliest event detected following CSFV infection is a decrease in lymphocytes number. With some CSFV strains this leads to lymphopenia, the severity varying according to strain virulence. This lymphocyte depletion is attributed to an induction of apoptosis in non-infected bystander cells. We c...

A functional memory T cell pool is critical for resistance to pathogen reinfection. Lymphopenia produces memory-like CD8(+) T cells through homeostatic proliferation, and such "HP-memory" cells can control lethal bacterial infections similarly to conventional, antigen-experienced, memory T cells. These 2 pathways for memory T cell generation are quite distinct. We show here, however, that simil...

Background: The Forkhead box protein N1 (FOXN1) is a key regulator of thymic epithelial development, and its complete deficiency leads to nude-severe combined immunodeficiency (SCID) phenotype. More recently, heterozygous mutations in FOXN1 have been linked with syndrome congenital lymphopenia wide clinical spectrum, most cases being caused by missense mutations. Aim: To broaden the genotypic p...

Percentage and absolute levels of circulating T lymphocytes were measured in 48 patients with bronchial carcinoma. These were compared with control values from nine healthy adults and 19 age-matched patients with benign disorders. A further 20 patients who had been given postoperative immunotherapy after complete resection of bronchial carcinoma were also studied. There was no significant diffe...