Differentiation of human B-cell malignant lymphomas is independent of the octamer lymphoid specific binding factor (Oct-2)

Abstract

We have shown previously that the presence and action of immunoglobulin gene promoter specific trans-acting factors correlates with the stages of 'differentiation' of human lymphoid neoplasms. The regulatory sequence described by us was located upstream of the octamer motif which is known to bind lymphoid specific trans-acting factor Oct-2. In the present study we attempted to establish if the Oct-2 factor was present in fresh human tissue of B-cell origin and if the levels of Oct-2 also correlated with the stages of human lymphoid differentiation. We applied DNA mobility shift assay using the same cases which we utilized in our previous work. We compared the levels of Oct-2 with the levels of ubiquitous octamer binding factor Oct-1. Oct-2 was present in all lymphoid cells of B-cell origin (from fresh surgical specimens and in long-term tissue cultured cells) with the exception of a pre-B-cell line NALM-6. The relative abundance of Oct-2 varied, however, and the ratio of Oct-2 to Oct-1 was variable in different types of B cells. This phenomenon did not correlate with the stages of differentiation of human lymphoid neoplasms. There was also no correlation between the expression of Oct-2 and levels of immunoglobulin-specific messenger RNAs. These findings indicate that the control of, immunoglobulin expression in relation to the differentiation of human B-cell neoplasms requires factors other than Oct-2.