Immunocytometric analyses of surface B29 and Ig μ heavy chain expression on normal and CLL patient B-cell samples. Surface B29 and μ chain expression was determined by dual staining on peripheral blood mononuclear B cells from a normal individual ([A], designated ++) and from 3 representative CLL patients distinguished on their expression of surface B29 and μ proteins. B-CLL cells from patient 44 ([B], designated ++) displayed apparently normal surface B29 and μ levels. B-CLL cells from patient 19 ([C], scored +) exhibited low levels of both proteins. B-CLL cells from patient 21 ([D], designated −) were scored negative for surface B29 and μ expression.