During the acute phase following antigen challenge, serum IgA (0.073 ± 0.005 vs. 0.044 ± 0.005 g/L) (P < 0.05) and IgG (0.54 ± 0.082 vs. 0.28 ± 0.049 g) (P < 0.01) levels significantly increased in HSP rats compared with controls. The gene discussed is CD79A; the disease is hereditary spastic paraplegia.