Detection of antibodies to the antigens involving differentiation of myeloid cells in sera from patients with systemic lupus erythematosus

The sera from 66 patients with systemic lupus erythematosus (SLE) were examined by the immunoblotting method to detect antibodies to the antigens on the cultured myeloid cell lines, fresh monocytes and granulocytes, and were compared with the sera from 26 healthy subjects sex- and roughly age-matched to the patients. The sera from SLE patients demonstrated antibodies to many antigens on myeloid cells at high frequencies, compared with healthy subjects. A high reactivity with similar patterns was demonstrated with K562, KG-1 and HL60 cells, while reactivity to U937, monocytes and granulocytes was rather low. In particular, the sera from SLE patients were found to contain the antibody to the antigens with Mr of 60K on K562, KG-1, and HL60 cells, which are known to express a good amount of c-myc products. However, the sera from healthy subjects demonstrated hardly any antibody to the 60K antigen on HL60 cells. After an incubation of HL60 cells with TPA or vitamin D3 to induce their monocytic differentiation, the SLE sera became able to detect the 55K antigen on the differentiated HL60 cells, while the 60K antigen turned to undetectable or only faintly detected. These findings suggested that the 60K antigen on HL60 cells may be related to a gene product involving cell growth or differentiation, such as c-myc protein. Actually, polyclonal antibody to myc-specific peptide could identify the 60K antigen as one of the cellular products of HL60.(ABSTRACT TRUNCATED AT 250 WORDS)