Patterns of T cell receptor gamma gene rearrangement and expression in B and T lymphoid malignancies

The frequency and pattern of T gamma gene rearrangement and expression was investigated in hematopoietic neoplasms including T and B lymphoid and myeloid malignancies. 39 of 39 T lymphoid neoplasms, including fresh cases and cell lines, were found to display clonal T gamma gene rearrangements. There was heterogeneity with respect to utilization of the two T gamma constant region genes, T gamma C1 and T gamma C2. In 31 cases (80%) T gamma C1 was deleted and T gamma C2 was rearranged, while in the remaining 8 cases (20%) T gamma C1 was rearranged. T gamma gene rearrangements were found in non-T cells, but were restricted to 6/17 (35%) immature B cell neoplasms. All 24 mature B cell and 14 myeloid neoplasms retained the T gamma germ line pattern. T gamma mRNA was found in all T cells tested. However, the majority (16/17) of T cells most likely do not express a T gamma protein since a T alpha/beta heterodimer detected by reactivity with the MoAb WT31 is present on the cell surface together with T3. These data suggest that T gamma gene rearrangements are universal in T cells and frequent in immature B cell neoplastic populations. However, expression of the T gamma protein is extremely infrequent, indicating that T cell neoplasms are very rarely derived from the recently identified T3+T gamma +T alpha/beta- peripheral T cell population.