The CD9 tetraspanin is not required for the development of peripheral B cells or for humoral immunity.
The CD9 tetraspanin is known to be expressed at high levels on marginal zone (MZ) B cells, B-1 B cells, and plasma cells, and its expression is believed to be dependent on signals derived via Btk. In CD9 null mice, however, the development and survival of MZ B cells, B-1 B cells, and plasma cells all appear to be unaffected, and humoral immune responses to T-dependent and T-independent Ags are similar to those seen in wild-type littermate controls. In wild-type mice, CD9 levels may serve to distinguish between the presumed MZ precursor B cell population in the spleen and other IgD-expressing transitional B cells that express lower levels of CD21 and CD1d. These results suggest that CD9 is dispensable for B cell development and humoral immunity, but that this protein may serve as an additional marker for the presumed MZ precursor population of splenic B cells.
Cariappa
Annaiah
A
Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA 02129, USA.
Shoham
Tsipi
T
Liu
Haoyuan
H
Levy
Shoshana
S
Boucheix
Claude
C
Pillai
Shiv
S
D000818:Animals; D000917:Antibody Formation; D015703:Antigens, CD / Q000502:physiology*; D001402:B-Lymphocytes / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D060245:Tetraspanin 29
D015703:Antigens, CD; C554870:Cd9 protein, mouse; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29