Tohru Yokoi

Expression of CD45R0 (UCHL1) by CD4^+ and CD8^+ T cells as a sign of in vivo activation in infectious mononucleosis

CD4SR0 (UCHL1), a member of leucocyte common antigen family, is expressed largely on previously activated or memory T cells. We examined CD45R0 expression of T cell subpopulations in patients with Epstein‐Barr virus (EBV) induced infectious mononucleosis (IMN) as a sign of in vivo activation. Consistent with the notion that activated CD8+ T cells expand in acute IMN, the majority of CD8+ T cells in patients with acute IMN expressed CD45R0 to the similar extent to HLA‐DR expression. Most CD4+ T cells in these patients also demonstrated marked expression of CD45R0 as well as HLA‐DR antigens, compared with age‐matched controls. Expression of CD45R0 by CD4+ T cells in patients with acute IMN was more notable than their HLA‐DR expression. While predominant CD8+ T cells resulted in decreased percentages of CD4+ T cells, CD4+ T cells expressing CD4SR0 were shown to be significantly elevated in absolute number. The results suggest that both CD4+ and CD8+ T cells may be activated by stimulation with EBV infection. The appearance of two T cell subpopulations expressing CD4SR0 in acute IMN implies their immunoregulatory roles in the control of EBV‐infected cells.

The Capability of Neonatal Leukocytes to Produce IL-6 on Stimulation Assessed by Whole Blood Culture

ABSTRACT: IL-6 is a cytokine with a wide variety of influences on the cells involved in immune and inflammatory responses. Defective production of IL-6 may be partly responsible for the impaired immune defense and inflammatory response often observed in the neonatal period. In our study, we used whole blood culture to examine the capacity of neonatal leukocytes to produce IL-6 in response to various stimuli. IL-6 activity was evaluated by growth promoting assay using an IL-6-dependent murine hybrid-oma clone. IL-6 activity was undetectable in fresh or unstimulated blood obtained from both newborns and adults. In contrast, incubation of whole blood with lipo-polysaccharide or concanavalin A resulted in marked IL-6 activity. After stimulation, IL-6 activity was induced as early as 2 h after culture and increased with time, reaching a plateau at around 12 h. Comparative examinations suggested that the IL-6 activity induced in neonatal blood on stimulation was similar to that seen in stimulated adult blood. Neutralization experiments with anti-IL-6 anti-serum confirmed the presence of IL-6 proteins in the stimulated blood, and induction of cellular IL-6 mRNA was demonstrated in the stimulated blood as well. In addition, immunocytochemical observations suggested that the major IL-6 producing cells in the stimulated blood may be monocytes. The results suggest that the production of IL-6 in response to specified stimuli is normal at birth.

A novel missense mutation in exon 8 of the ornithine transcarbamylase gene in two unrelated male patients with mild ornithine transcarbamylase deficiency

SummaryWe studied two unrelated male probands with mild ornithine transcarbamylase (OTC) (E.G.2.1.3.3) deficiency presenting a similar clinical course. Previous analyses of their liver OTCs also revealed similar properties. To identify the underlying molecular defects, we first cloned the entire coding region of the OTC gene from one proband and found a single base-substitution (C to T) leading to the substitution of tryptophan for arginine at amino acid position 277. Using a genomic amplification technique followed by allele specific oligonucleotide hybridization, we identified the same point mutation in the OTC gene of the other proband. We observed the presence of the mutation among family members in at least three generations, and in one asymptomatic hemizygous sibling in each family.

A 3′ splice site consensus sequence mutation in the intron 3 of the α-galactosidase a gene in a patient with Fabry disease

SummaryFabry disease is an X-linked disorder accompanied with accumulation of glycosphingolipids resulting from the deficient activity of the lysosomal hydrolase, α-galactosidase A (α-GalA). In the present study, mRNA for α-GalA in fibroblasts from an 11-year-old Japanese patient with Fabry disease was examined using the reverse transcriptase-polymerase chain reaction (PCR). The shorter message of α-GalA was demonstrated in this patient when compared with the normal control. The complete deletion of exon 4 in the mRNA for α-GalA in the patient was disclosed by analysis of cDNA with restriction enzyme digestion and asymmetrical PCR sequencing. The direct sequencing of the genomic DNA demonstrated a single base substitution (G→A) at the 3′ end of the consensus sequence of intron 3. This mutation destroyed a splice site in the α-GalA, which produced a mutant allele. It was also shown that the mother of the patient had this mutant as well as normal alleles as a heterozygote.

Kawasaki disease with a concomitant primary Epstein‐Barr virus infection

A two year old boy exhibited not only clinical manifestations which suggested a recurrence of Kawasaki disease (KD) but also evidence of a primary infection by Epstein‐Barr virus (EBV) including tonsillitis, splenomegaly and atypical lymphocytosis in the peripheral blood. An inverted CD4/CD8 ratio in lymphocyte subsets suggested the presence of infectious mononucleosis (IM). Epstein‐Barr virus titers (viral capsid antigen‐immunoglobulin G 1:20; Epstein‐Barr virus‐associated nuclear antigen < 1:10) showed an acute EBV infection and the presence of EBV genome in the blood was determined by the polymerase chain reaction technique. In Japan, the peak incidence of KD and IM is in children under 4 years of age. From the investigation of EBV titers, it has been reported that some patients with KD develop an associated, unusual primary EBV infection. Kawasaki disease concurrent with a primary EBV infection as in this case, suggests the possibility of an etiologic agent related to the KD rather than to the EBV infection itself.

Immune status in two brothers with Omenn's syndrome: no discernible chimerism on FACS analysis using a monoclonal antibody specific for a maternally restricted HLA antigen.

Sequential immunologic examinations, including lymph node biopsies, in two brothers with clinical characteristics of Omenns syndrome are presented in this study. Although the number of circulating T cells with mature phenotype (OKT3+, TCR1+) was within normal range, the lymphocyte proliferative response to mitogens was poor. Examinations of the lymph nodes revealed marked lymphoid depletion associated with eosinophilic infiltration and reticular cell proliferation. Over the clinical course of 5 months, circulating T cells also mostly disappeared. Thymic hypoplasia was noted at autopsy. Although intrauterine graft-versus host disease (GVHD) has been hypothesized as being the pathogenetic mechanism in this syndrome, maternal lymphocytes circulating in these patients were not identified either by karyotype and HLA typing or by highly sensitive FACS analysis and immunohistochemical studies using a monoclonal antibody, HLA-A9, specific for a maternally restricted HLA antigen, Aw24. In conclusion, the familial occurrence and the absence of maternal chimerism might be the essential features of Omenns syndrome which should be differentiated from fetal GVHD.