Antibody responses to modified MSA in normal C57BL/6J and T-cell-deficient nude mice. The mice were immunized with the indicated aldehyde-modified MSA, native MSA, or PBS. Serum was collected after the second booster immunization. IgG antibody titres to respective immunogen were measured by ELISA using serum diluted 1:500. MDA, malondialdehyde; NonRed, reduced nonanal; HNE, 4-hydroxynonenal; Nat, native MSA. Values are means from four animals in each group, error bars are SEM.