Inhibitory effect on arterial injury-induced neointimal formation by adoptive B-cell transfer in Rag-1 knockout mice

We investigated the effect of B-cell reconstitution in immune-deficient Rag-1 knockout (KO) mice subjected to arterial injury. After 21 days, injury induced a 4- to 5-fold increase in neointimal formation in Rag-1 KO mice fed normal chow compared with wild-type (WT) mice (0.020+/-0.0160 [n=8] versus 0.0049+/-0.0022 [n=8] mm(2), respectively; P<0.05) and in western-type diet-fed Rag-1 KO mice compared with WT mice (0.0312+/-0.0174 [n=7] versus 0.0050+/-0.0028 [n = 6] mm(2), respectively, P<0.05). To investigate the role of B cells in response to injury, Rag-1 KO mice were reconstituted with B cells derived from the spleens of WT mice, with donors and recipients on the same diet. Reconstitution of Rag-1 KO mice with B cells from WT mice (both fed normal chow) reduced neointimal formation compared with the effect in unreconstituted Rag-1 KO mice (0.0076+/-0.0039 [n=9] versus 0.020+/-0.0160 [n=8] mm(2), respectively; P<0.05). Reconstitution of Rag-1 KO mice with B cells from WT mice (both fed a western diet) reduced neointimal formation compared the effect in Rag-1 KO mice (0.0087+/-0.0037 [n=8] versus 0.0312+/-0.0174 [n=7] mm(2). respectively; P<0.05). Injured carotid arteries from reconstituted Rag-1 KO mice had detectable IgM and IgG, indicating viable transfer of B cells. The results suggest that B cells modulate the response to arterial injury.