![]() ![]() Gaw, 513 Parnassus Ave, HSE16, San Francisco, California 94143, USA. Edwards School of Medicine, Huntington, West Virginia, USA.ġ4Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, USA.ġ5Department of Obstetrics and Gynecology, UCLA, Los Angeles, California, USA.ġ6Department of Obstetrics, Gynecology & Reproductive Sciences,ġ8Department of Microbiology and Immunology, UCSF, San Francisco, California, USA.Īddress correspondence to: Stephanie L. These findings, and the fact that the oligoclonal IgA and IgM repertoires in a noninductive site of the mucosal immune system (parotid gland) become polyclonal in piglets reared germfree, suggest that initial expansion of the switched cells in the B cell compartment of fetal and neonatal piglets is not driven by environmental Ag.1Gladstone Institute of Virology, Gladstone Institutes, San Francisco, California, USA.ĢMichael Hulton Center for HIV Cure Research at Gladstone, San Francisco, California, USA.ĤCenter for Reproductive Sciences, Department of Obstetrics, Gynecology & Reproductive Sciences, UCSF, San Francisco, California, USA.ĦDivision of Pediatric Infectious Diseases and Global Health,ħDepartment of Bioengineering and Therapeutic Sciences,ĨDepartment of Family Health Care Nursing, andĩDepartment of Laboratory Medicine, UCSF, San Francisco, California, USA.ġ0Department of Pediatrics, Division of Neonatology, Santa Clara Valley Medical Center, San Jose, California, USA.ġ1Stanford-O’Connor Family Medicine Residency Program, Division of Family Medicine, Stanford University, Palo Alto, California, USA.ġ2Department of Pediatrics, Division of Neonatology, andġ3Department of Obstetrics and Gynecology, Marshall University Joan C. Thus, switch recombination in fetal life does not appear to be driven by environmental Ag and is only weakly coupled to VDJ diversification. However, VDJs expressed with switched isotypes were more diversified than those expressed with IgM. The complementarity-determining region 3 spectratypes of thymic IgA and IgG transcripts at 70 and 90 days, respectively, were as polyclonal as that of IgM, indicating a broad repertoire of switched B cells although the VDJs transcribed with these switched isotypes in normal fetuses were not diversified in comparison to those from animals exposed to environmental Ags such as age-matched, virus-infected fetuses, colonized isolator piglets, and conventional adults. Data on transcription, secretion, and serum isotype profiles suggest that although all fetal IgA and IgM may result from de novo synthesis, some IgG may result from low-level selective transport. Although transcripts for IgM could be recovered at DG 50 (114 DG is full gestation) in all major fetal lymphoid tissues, those for IgG and IgA first became prominent at 60 DG in thymus, and transcription and spontaneous secretion became especially pronounced in this organ in older fetuses. Analysis of Ig levels and Ig isotype profiles in >150 normal and virus-infected fetuses from 38-110 days of gestation (DG) suggested that IgG, IgA, and IgM were most likely the result of de novo fetal synthesis. The epitheliochorial placenta of swine is considered a barrier to Ag and selective transport of IgG, so this species should be an excellent model with which to determine whether switch recombination is Ag dependent. ![]()
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