The IPP had previously been implicated as an important site for Ig diversification in sheep and cattle but the early site for Ig diversification in sheep remained in question. Recently, fetal spleen has been shown to be a potential site of B cell development in cattle which is phylogenetically close to sheep (Lucier et al., 1998). In this study, in order to solve the problem of when, where, and how the primary immunoglobulin repertoire of sheep is generated and diversified before the onset of diversification in IPP, various tissues of fetuses at the first trimester were examined for the expression of λ light chain genes and the degree of Vλ diversity. Thus, this study has provided significant evidence for the following conclusions on early Ig Vλ diversification in sheep: (1) Two germline Vλ genes, 5.1 and 5.3 were identified as predominant participants in Ig λ light chain gene rearrangement. (2) A new Jλ gene was found and shown to be utilized in Ig λ light chain gene rearrangement. (3) At 63 days of gestation, there is little diversity seen in the Ig λ light chain repertoire outside the spleen. However, even at this early stage, there is significant diversity of λ light chain within spleen. (4) Fetal spleen is already a reservoir of extensive Ig diversity by the end of the first trimester. (5) Spleen is an earlier site of Vλ diversity than IPP, a bursa-equivalent GALT in sheep. (6) Fetal spleen may provide a partially diversified B cell stock from which a small number of precursor B cells emigrate into the IPP and undergo subsequent clonal expansion and additional diversification within the IPP follicles in sheep. (7) This study shows that multiple sites are involved in the diversification of the Vλ repertoire in sheep.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-3256 |
| Date | 01 January 1999 |
| Creators | Jeong, Youngkee |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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