The relationship between surface immunoglobulin isotype and immune function of murine b lymphocytes: I. Surface immunoglobulin isotypes on primed b cells in the spleen*

We investigated the ability of IgM-, IgD-, and IgG-bearing cells from the spleens of (BALB/c × C57BL/Ka)F₁ mice primed to dinitrophenyl-bovine serum albumin (DNP-BSA) to restore the adoptive secondary anti-BSA and anti-DNP antibody responses. A rabbit anti-mouse IgD antiserum was prepared and the specificity documented by radioimmunoprecipitation, and cell surface staining. Purified populations of IgM-, IgD-, and IgG-bearing cells were prepared by immunofluorescent staining with isotype-specific reagents, and sorting on the fluorescence activated cell sorter. Bright or dull cells were transferred to irradiated syngeneic recipients which were challenged with DNP-BSA in saline. Unfractionated spleen cells restored an adoptive secondary serum antibody response which was all IgG (2-mercaptoethanol resistant). Purified IgM- or IgDbearing cells restored both the secondary IgM and IgG antibody response. IgGbearing cells restored only the IgG response. In addition, the IgG-bearing cells appear to suppress the adoptive secondary IgM response, since depletion of IgGbearing cells from transferred spleen cells results in a marked increase in the adoptive IgM response.