Hypermutation, diversity and dissemination of human intestinal lamina propria plasma cells

Abstract

In this work we have microdissected lamina propria plasma cells and used polymerase chain reaction and sequencing to investigate immunoglobulin (Ig) gene rearrangements and mutations in human intestine. In addition, specific primers were designed for individual Ig gene rearrangements to analyze the distribution of related B cell and plasma cell clones at different sites along the bowel. Confirming our earlier work, intestinal IgVH genes were highly mutated in plasma cells from older individuals (> 30 years). IgVH genes were significantly less mutated in samples taken from patients aged 11-30 years, and there were fewer mutations again in samples from young children (< 11 years). In age-matched specimens the number of mutations was equivalent in the duodenum and colon. Using complementarity-determining region 3 primers to amplify specific Ig gene rearrangements, evidence was also found for the existence of related lamina propria plasma cells along the small bowel and colon, although these were quite scarce. In addition, analysis of the numbers of related clones in a random sampling from discrete areas of lamina propria indicates that the local population is diverse. These results suggest that the highly mutated IgVH genes in adult intestinal plasma cells are a consequence of chronic antigen exposure with age. Duodenal plasma cells are as highly mutated as colonic plasma cells, despite the fact that the upper bowel has no indigenous microbial flora (the stimulus for intestinal plasma cells). They also show that the plasma cell population is diverse and can be widely disseminated along the bowel.

Characteristics of Human IgA and IgM Genes Used by Plasma Cells in the Salivary Gland Resemble Those Used in Duodenum But Not Those Used in the Spleen

“…This included isotype-switched variants in the salivary gland. Examples of related plasma cells have been seen before in the gastrointestinal tract (10,11,17), where the related cells can either be clustered locally (more commonly seen) or disseminated along the bowel. The salivary gland preparations were taken from opposite sides of the tissue block and were ϳ5-10 mm apart.…”

“…The diversity of cells of B lineage can be investigated by analyzing their Ig heavy chain genes (Ig H ) 3 (10,11). The diversity of human Ig genes is achieved through the processes of gene rearrangement and somatic hypermutation.…”

“…IgA genes generally have higher numbers of mutations than IgG genes, which in turn have a higher number of mutations than IgM genes (16 -18). We have previously found, in humans, that B cells and plasma cells from the duodenum, ileum, and colon carry Ig H genes that have a much higher level of mutation (10,11,17,19). The reasons for the higher level of mutation are not yet known.…”

Applications of immunochemistry in human health: advances in vaccinology and antibody design (IUPAC Technical Report)

“…Glycosylation sites are located in the Fc but also in the Fv region [345,346]. The most common N-glycosylation site in the variable region is CDR2 of the heavy chain, but other potential N-glycosylation sites can be generated by somatic mutations [347]. The presence of glycosylation in the variable region may have either positive of negative effects on the antigen binding, and the difference in the carbohydrate structure could also influence the pharmacokinetics [348,349].…”

Molecular characterization of the cervical and systemic B-cell repertoire

“…[19][20][21] The human immunoglobulin heavy chain complex is located primarily on chromosome 14, 22 and consists of 123-129 V H , [23][24][25] 27 diversity (D H ), 26,27 9 junction (J H ) 28 and 11 constant (C H ) gene segments. 29,30 The V H gene segment can be grouped into seven families (V H 1-7) based on sequence homology among framework regions (FR) 1, 2 and 3 and complementarity determining regions (CDR) 1 and 2.…”