ABSTRACT
Abstract ................................................................................................. 160 7.1 Introduction .................................................................................. 160 7.2 The Piglet Model for Developmental Immunology ..................... 161 7.3 B Cell Lymphogenesis and Immunoglobulin Levels ................... 164 7.3.1 B Cell Lymphogenesis and Preimmune Repertoire
Development .................................................................... 164 7.3.2 Immunoglobulin Concentrations in Sera and Secretions.... 166 7.4 The Constituency and Organization of the Porcine Ig Loci ........ 168 7.4.1 The Porcine Variable Heavy Chain Locus ....................... 168 7.4.2 The Porcine Constant Heavy Chain Locus and IgG
Subclass Heterogeneity .................................................... 169 7.4.3 The Porcine Light Chain Loci.......................................... 171 7.5 Genetic Variation Among Porcine Ig Genes ................................ 173 7.6 The Expressed Pre-Immune Antibody Repertoire ....................... 176 7.6.1 The Preimmune Repertoire .............................................. 176 7.6.2 Diversification of the Preimmune Repertoire
after Environmental Exposure ......................................... 178 7.7 Conclusion ................................................................................... 180 Acknowledgement ................................................................................ 182 Keywords .............................................................................................. 182 References ............................................................................................. 182
ABSTRACT
Developing the piglet as a model for developmental immunology required characterization of the porcine immunoglobulins (Igs) and the genes encoding them. Swine have genes encoding the same five classes of Igs as most other mammals including six IgG subclasses. Allelic variants for IgA and IgG subclasses are also recognized. The IGHC genes are arranged as in other mammals, preceded by switch regions including a short one for IgD. Whether IgD in swine is expressed as a B cell receptor (BCR) like IgM, is unknown. Sequences for ~30 IGHV genes have been reported but only the 15 most 3′ IGHV genes in one haplotype have been mapped. Three of the IGHV genes account for ~60% of the preimmune heavy chain repertoire and this changes little after antigen exposure. Swine have only two functional DH (IGHD) segments and one IGHJ so disruption of the latter generates B cell knock-out pigs. There are nine functional IGLV genes and nine functional IGLK genes yet two IGLK and three IGLV genes comprise 70-80 of the preimmune light chain repertoire. Unlike mice, lambda rearranges >30 days before kappa and the question of whether there is a preBCR is unresolved.
