ANTI-IMMUNOGLOBULIN STIMULATION OF MURINE LYMPHOCYTES .2. IDENTIFICATION OF CELL-SURFACE TARGET MOLECULES AND REQUIREMENTS FOR CROSS-LINKAGE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 117  (5) , 1527-1531
Abstract
Splenic B [bone marrow-derived] cells from normal mice, 7 mo. of age or older, can be stimulated to proliferate in vitro with soluble anti-immunoglobulin (Ig) reagents. To investigate whether the integrity of the anti-Ig molecule is necessary for stimulation, and to determine whether cross-linkage of cell surface Ig is required, experiments were done by using F (ab'')2 fragments and Fab monomers prepared from anti-mouse IgM serum. To determine whether antibodies directed against H chains would induce cell proliferation, class-specific antisera were prepared and tested. Cell proliferation was induced by F (ab'')2 fragments, but not by Fab monomers. Cell proliferation was obtained with monospecific antiserum directed against .mu. H chains but not with antisera directed against .alpha.- or .gamma.- chains. Thus, cross-linkage of .mu. H chains on the B cell surface is required for soluble anti-Ig-induced proliferation. The nature of the age-associated response was investigated by comparing membrane Ig density and class on spleen cells from old and young (2-3 mo.) mice; no differences in surface Ig were found which would explain the age-associated response to anti-Ig reagents.