Synthesis of a Viral Protein with Molecular Weight of 30,000 (p30) by Leukemic Cells and Antibodies Cross-Reacting with Simian Sarcoma Virus p30 in Serum of a Chronic Myeloid Leukemia Patient

Abstract

We studied a patient with a Philadelphia chromosome-positive chronic myeloid leukemia, who died in relapse after multiple transfusions and grafting with bone marrow from his monozygotic twin brother (referred to as “donor” in this paper). We present data indicating that this patient may have had a retrovirus infection and that this virus is related to the group of exogenous primate type C retroviruses.

Antibodies to simian sarcoma virus (SSV) M.W. 30,000 protein (p30) but not endogenous feline virus RD-114 could be found in patient but not donor serum. Patient but not donor cells were able to actively synthesize a p30 protein that could be precipitated with patient serum and rabbit anti-SSV p30 but not with donor serum or rabbit anti-RD-114 p30. Patient p30 resembles SSV p30 but not RD-114 p30 in peptide mapping by limited proteolysis and subsequent slab gel electrophoresis. Patient but not donor cells were able to actively synthesize a M.W. 78,000 protein that could be precipitated with goat anti-SSV. An enzyme with properties of reverse transcriptase was increased 30-fold in patient cells when compared with donor and other control cells.

Related to the presence of widespread infectious agents may be the finding that, in the course of the patient's disease, donor serum showed increasing amounts of possibly immunoregulatory (Cancer Research, submitted for publication) antibodies, reactive with autologous and, more effectively, with patientderived cell membrane M.W. 80,000 protein (a possible idiotypic receptor structure) and M.W. 94,000 protein (a T-cell alloantigen).