Production of Peptide of Retroviral Origin in Sera of Patients with Chronic Myeloid Leukemia at Acute Phase.

In the present study we investigated production of the peptide of retroviral origin in patients with various types of leukemia. For this purpose the high affinity rabbit antibodies were generated against the synthetic peptide representing the "immunosuppressive motif" within the envelope protein of human endogenous retrovirus type C. The presence of this peptide was identified only in sera of the patients with chronic myelo- and/or promonocytic leukemia at acute phase. Furthermore, the appearance of this protein correlated with agranulocytosis. SDS-PAGE profile revealed the serum protein recognized by Ab that had MW of 88 kDa. However, in bone marrow cells, the same Ab bound 66 kDa peptide, and low molecular weight peptide, INF-agr;, as well. It was determined that 88 kDa protein was a highly glycosylated version of 66 kDa protein. Staining blood cells and bone marrow cells with FITC-labelled specific monoclonal antibodies demonstrated that CD34(+) cells produced this peptide. The appearance of this peptide in sera of patients with myeloid leukemia was considered as unfavorable prognosis since it was followed with lethality in 50% of cases. Thus, besides potential involvement of endogenous retroviral products in carcinogenesis, they may be considered as a factor of immunosuppression.