sentences:  B cells that respond most avidly to antigen are preferentially allowed to proliferate and mature, a process known as clonal selection.In lymphocytic neoplastic diseases such as multiple myeloma and lymphoma, but also other illnesses, there can be a massive expansion of a single B-cell clone, detectable by measuring the excessively-produced antibodies, measured in a serum protein electrophoresis test or peripheral blood flow cytometry.Such an expansion is said to be "monoclonal", and monoclonal antibodies produced by such a group of B cells can cause illnesses such as amyloidosis and lupus, or can be indicative of an underlying malignancy.