T Cell Epitope Analysis of Structural Protein of Adenovirus / 대한면역학회지

Thelper (Th) cells play a pivotal role in the regulation of immune responses. Since Th epitopes in adenovirus have not yet been defined, in this study, it was attempted to search for Th epitopes of adenovirus antigens that are restricted by MHC class II (H-2E). Among candidate viral proteins to be screened for Th epitopes, structural protein was selected, since they induced strong IL-2 release from adenovirus immune lyrnph node (LN) cells and the presence of E1 protein, which contains immunodominant cytotoxic T lymphocyte epitopes, did not potentiate the T cell responses. To confirm the presence of Th epitopes in the structural protein, virions were trypsinized and the resulting polypeptides whose molecular weights were lower than 5,000 were fractionated by HPLC. Some of the HPLC fraction turned out to induce LN cell proliferation. Ten synthetic peptides were designed as candidate Th epitopes from the primary amino acid sequences of adenovirus hexon and penton protein which are major constituents of the virion. The selected sequences share the common features of other known H-2E' binding ligands. Among these ten synthetic peptides, peptide of hexon protein amino acid residue 709-721 induced noticeable proliferation of LN cells from preimmune mice, and also able to induce IL-2 secretion from adenovirus-specific T hybridomas, suggesting that the peptide was the most immunodominant Th epitope. Hexon protein 221-233 and hexon protein 676-688 are considered as epitopes also. This study revealed three epitope sequences from adenovirus structural protein that are presented by class II MHC, H-2E.

Generation and Characterization of Alloenic Radiation Bone Marrow Chimera / 대한면역학회지

Allogenic bone marrow chimera has been used to study the differentiation of donor-derived bone marrow cells under the recipient thymic environment, tolerance generaion between recipient and donor cells. We prepared H-2' to H-2 allogenic chimera by transfering bone marrow cells from H-2dmice to r-irradiated H-2k mice, and examined the differentiation ofthe bone marrow cells under allogenic environment. Complete reconstitution with H-2d+ phenotype cells in the thymus of the chimera mice was observed. However, the number of CD4- CD8+ cells dramatically decreased under the recipient thymic environment, CD8+ cells significantly reduced also in spleen and lymph node, compared with that of normal mice. Interestingly, we also observed coexistence of donor-derived cells (H-2k) and recipient derived cells (H-2d) in lymph node and spleen in the chimera. These results suggested that the decrease of CD4-CD8+ cells could be caused by r-irradiation by affecting the recipient thymic environment, and that in this chimera, tolerance between donor-derived cells and recipient-derived cells was maintained.

Intravenous immunoglobulin for prophylaxis of neoneatal sepsis in the premature infants

Newborn premature babies have lwo levels of transplacentally acquired maternal immunoglobulin which is mostly transferred after 32~34 weeks gestaton, therefore they may have IgG deficiencies that increase their susceptibility to bacterial infection. We performed this study to determine whether intravenous immunoglobulin (IVIG) therapy improves mortality or infection occurrance rate. From 1 october 1991 to 31 July 1992, 73premature newborn infants with gestational age< or =34weeks were enrolled: the theatment group, consisting of 43infants who received prophylactic intravenous immunoglobulin therapy (500mg/kg/week) and the control group, consisting of 30infants who did not receive. prophylactic intravenous administration of immunoglobulin to preterm infants with a gestational ageage< or =34week, at a dose of 500mg/kg/week, results in maintenance of a satisfactory serum IgG level throughout the high-risk period for infection. But the incidence rates of proven or very probable sepsis, mortality for sepsis and total mortality in the infants receiving intravenous immunoglobulin were not significant differences when compared with those in the control infants. No adverse effects were noted after immunoglobulin transfusions in our subjects. In conclusion, our study does not show any decrease in bacterial infection rate or in mortality rate, and no study in the literature has shown absolute proof of the prophylactic efficacy of IVIG in premature newborns. Larger studies are necessary to confirm these observations and to determine more effective dosing schedules and the optimal levels of orhanism-spectific antibodies. And specific hyperimmnue of monoclonal antibody preparations may be required to provide reliable sources of effective prophylactic to premature neonate with high risk in bacterial sepsis.

Comparison between preterm and fullterm infants in neonatal sepsis

We retrospectively evaluated datas on 61 cases of neonatal sepsis confirmed by clinical symptoms and blood cultures at the NICU of Gil general hospital From Mar. 1989, to Fed. 1992. The results obtained were as follows: 1) The mean gestational age was 32.7+/-2.6 Weeks in preterm infants, and 39+/-1.5 weels on term infants. The mean birth weight was 1,701.4+/-422.4 g in preterm infants, and 3,232+/-581.7 g in term infants. 2) There were 61 infants with neonatal sepsis identified among 13, 486 live births, resulting in an incidence of 0.45%. The sex ratio of male to female was 1.2:1. The incidencdence was higher in preterm infants (2.21%) than in term infants (0.27%). 3) The most commom presenting symptoms of neonatal sepsis were apnea and bradycardia (53.6%) in preterm infants, jaundice (33.3%) in term infants 4) The concurrent diseases in neonatal sepsis were urinary tract infection (UT)(25%), pneumonia (21%), hyaline membrane disease (21%) in the order of frequency. Hyaline membrane disease (33.3%) was the most frequently associated disease in preterm infants, UTI (41.4%) in term infants 5) Gram positive organisms were isolated in 33 casess (52%), gram negative organisms in 30 cases (48%). The most common ortanism isolated from blood cultures was CONS (28.6%). The more common organisms in preterm infants were CONS (26.7%), Enterococcus (23.3%) and Klebsiella (10%). CONS (30.3%), E. Coli (27.3%) and Staphylococcus aureus (12%) were more frequent in term infants. 6) The significant diagnostic laboratory findings for neonatal sepsis were leukopenia ( or =1+.2 or more of abnormal hematologic values were significantly more frequent in preterm infants (P or =24hrs)(9.0%) in term infants. 8) Early onset neonatal sepsis (72< or =hr of age) was found in 40 cases (65.6%). 9) The overall mortality rate of neonatal sepsis was 26.0%(39,3% in preterm infants, 15.2% in term infants). The mortality rate was significantly high in pseudomonas infection. 10) In low birth weight infants, the susceptibility to neonatal sepsis was greatest in the infants of lowest birth weight (1,00-1,500 gm) and the mortality rate was inversely proportional to birth weight. 11) Sensitivity to antibiotics in gram postitive organisms were chlorampjenicol (37%), Erythromycin (29%), ampicillin (26%) and cephalothin (26%). It clearly showed that newer antibiotics such as vancomycin is neccessary. In cases of gram negative organisms, sensitivity to antibiotics were amikacin (85%), gentamicin (65%), tobramycin (58%) and cephalothin (54%).