Expression of mouse CD43 in the B cell lineage of transgenic mice causes impaired immune responses to T-independent antigens

✍ Scribed by Julie R. Ostberg; Leonard L. Dragone; Melinda A. Borrello; Richard P. Phipps; Richard K. Barth; John G. Frelinger

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 898 KB
• Volume: 27
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830270906

✦ Synopsis

Expression of mouse CD43 in the B cell lineage of transgenic mice causes impaired immune responses to T-independent antigens CD43 (leukosialin), a sialylated glycoprotein expressed on the surface of most hematopoietic cells, has been implicated in cell adhesion and signaling. However, its precise physiological function remains unclear. We used mouse CD43 (mCD43)-immunoglobulin enhancer-transgenic (TG) mice to study the role of mCD43 in vivo. Previous work revealed that mCD43 expression on mature B cells in these mice resulted in immunodeficiency to T-dependent (TD) antigens (Ag), possibly by impairing B-T cell interactions. In the present study we have immunized the TG mice with the T-independent (TI) Ag fluorescein-(Fl) lipopolysaccharide (LPS) (TI type 1 Ag) and F1-Ficoll (TI type 2 Ag). Surprisingly, the mCD43-Ig enhancer expressing mice were impaired in their ability to mount humoral responses to both FI-LPS and F1-Ficoll, and had decreased numbers of cells responding to Ag in vivo. Flow cytometric analysis was performed on peritoneal B-l cells, a population which often plays a major role in humoral responses to TI Ag such as bacterial Ag. This analysis revealed similar B220, IgM and CD5 expression patterns for the TG and nontransgenic (NTG) B-1 cells. In addition, purified peritoneal B-1 cells from TG and NTG mice were able to respond to LPS. Stimulation of splenic B cells in vitro with Fl-LPS and F1-Ficoll revealed that, in contrast to NTG B cell responses, TG B cell responses could not be enhanced by co-culture with T cells. However, soluble T cell factor enhancement of the TG B cell responses was normal. These data suggest that the mCD43 expression on B cells may inhibit cell interactions that are important for enhanced TI Ag responses. The anti-adhesive forces of mucins in general may thus be critical in regulating both TD and TI humoral responses.