Presence of germline and full-length IgA RNA transcripts among peritoneal B-1 cells.
Next to conventional B cells (or B-2 cells), peritoneal B-1 cells have been shown to contribute significantly to the production of IgA-secreting plasma cells in the gut. Evidence for this was mainly based on studies comprising manipulated animals, including lethally X-irradiated and transgenic mice. To examine the ability of peritoneal B-1 cells from untreated mice to switch actively to IgA in vivo, we performed RT-PCR analysis on FACS-sorted peritoneal B-cell subsets from untreated BALB/c mice in order to examine the presence of germline C alpha mRNA and mature C alpha mRNA transcripts. Germline C alpha and mature C alpha transcripts were readily detectable in peritoneal B-1 cells (defined as IgMbright/IgDdull), but not, or very little, in peritoneal B-2 cells (defined as IgMdull/IgDbright). Moreover, by subdividing the B-1-cell population in CD5+ B-1a cells and CD5- B-1b cells, it was shown that in vivo expression of germline C alpha and mature C alpha transcripts was largely restricted to the B-1b-cell lineage. These results indicate that peritoneal B-1 cells indeed are capable to switch to IgA under normal physiological conditions and hereby further support the view that B-1 cells contribute significantly to the mucosal IgA response, albeit this function appears to be restricted to the B-1b-cell subset.
de Waard
R
R
Department of Histology and Cell Biology, University of Groningen, The Netherlands.
Dammers
P M
PM
Tung
J W
JW
Kantor
A B
AB
Wilshire
J A
JA
Bos
N A
NA
Herzenberg
L A
LA
Kroese
F G
FG
D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D005260:Female; D007070:Immunoglobulin A / Q000235:genetics*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010529:Peritoneal Cavity / Q000166:cytology*; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats
D007070:Immunoglobulin A; D012333:RNA, Messenger