VARIABLE REGION STRUCTURE AND STAPHYLOCOCCAL PROTEIN-A BINDING-SPECIFICITY OF A MOUSE MONOCLONAL IGM ANTI-LAMININ-RECEPTOR ANTIBODY

Staphylococcal protein A is a cell wall-attached polypeptide that acts as a B-lymphocyte superantigen. This activation correlates with speci fic V-H gene segment usage in the B-cell receptor. B-cell receptor ass embled from members of the V(H)3 family in humans, or S107 family in m ice, has an intrinsic affinity for protein A. Human V(H)3-derived anti bodies bind to domain D of protein A. We have characterized a mouse Ig M monoclonal antibody that binds protein A. The sequencing of the vari able region suggests an almost germline-encoded V-H derived from S107 family and a V kappa 8-derived V-L. The binding specificity of the mon oclonal antibody was tested with various recombinant constructions der ived from protein A. We show that, unlike human V(H)3-derived antibody , mouse S107-derived immunoglobulin binds to the B domain of the bacte rial superantigen.