ANTIBODY-RESPONSE OF MURINE B1 CELLS TO HEN EGG-WHITE LYSOZYME

Cell transfer studies were performed to investigate the ability of mur ine peritoneal B1 cells to produce specific IgG antibody against the T -dependent protein antigen, hen eggwhite lysozyme (HEL). Peritoneal ce lls (PeC) from normal BALB/c mice were transferred into newborn, allot ype-congenic, C.B-17 severe combined immunodeficient (SCID) mice alone or together with splenic T cells from HEL-primed C.B-17 mice. After i mmunization with HEL, only those mice that received both PeC and prime d T cells produced HEL-specific IgG of the PeC donor allotype. To iden tify the B cell subset responsible for antibody production, PeC were s orted before transfer into B1 and conventional B (B2) cell populations . It was found that transfer of purified B1 cells plus primed T cells resulted in high levels of IgG1 anti-HEL in approximately half of the SCID recipients, while mice receiving B2 cells produced little detecta ble antibody. The responses consisted primarily of IgG1 kappa anti-HEL , with no significant IgM or lambda-bearing components. Seventeen HEL- specific hybridomas of BALB/c origin, i.e., derived from the B1 cell d onor, were obtained from reconstituted SCID mice after various periods of immunization and analyzed for fine specificity using a panel of av ian lysozymes. All but one of the B1 cell-derived mAbs recognized an H EL epitope not present on the closely related bobwhite quail lysozyme (differing from HEL at only 4 of 129 amino acid positions). While IEF analyses demonstrated the presence of extensive clonotypic diversity, the epitope specificity pattern, which is rare among B2-cell-derived a ntibodies, suggests that the B1 cell recognition repertoire for HEL is severely limited. (C) 1995 Academic Press, Inc.