Transient activation of the interleukin-2 (IL-2) gene after antigen recognition by T lymphocytes is crucial for subsequent T cell proliferation and differentiation. Several IL-2 gene regulatory elements and binding factors necessary for activation of the IL-2 gene have been defined. However, little is known about negative regulation of IL-2 expression, which is likely to be important in the rapid shut-off of IL-2 transcription. A nucleotide sequence element (NRE-A) that negatively regulates IL-2 expression has been identified within the IL-2 gene. T cell nuclear extracts contained an NRE-A binding activity. A complementary DNA was isolated that encodes a zinc finger-containing protein that suppressed IL-2 gene expression. The observation of negative regulation of the immunoglobulin heavy chain gene enhancer by an element similar to NRE-A suggests that related proteins may regulate multiple immune response genes.

High-risk maternal populations, which may provide access to ethnic minorities targeted for some UCB banks, may contain low percentages of eligible donors. Further refinement of donor criteria will be important in the evolution of UCB banking and transplantation.

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The uptake of deoxyglucose was compared in BHK cells and in DMN4B cells, a conditionally transformed line of BHK cells which exhibits transformed behavior a t 38.5' but not at 32'. At 32', DMN4B cells took up deoxyglucose more slowly than BHK cells, reflecting a higher Km for uptake of this sugar. When both cell lines were grown at 38.5', the Km for DMN4B cells was reduced to a level only slightly greater than for BHK cells, and deoxyglucose uptake became similar in the two cell lines. Growth in glucose-free medium for 22 hours stimulated deoxyglucose uptake in both BHK and DMN4B cells; under these conditions, uptake was equal in the two cells lines, both at 32' and 38.5'. Glycolysis, as measured by lactic acid production, was slower in DMN4B than BHK cells, but in contrast to deoxyglucose uptake, this difference was observed a t 38.5' rather than 32' . The observation that the subnormal deoxyglucose uptake of DMN4B cells in the untransformed state (32') can be normalized by growth a t 38.5', a temperature permissive for transformation, suggests that membrane changes facilitating sugar uptake, which have been found in other transformed cells, are associated with transformation in DMN4B cells as well. However, the failure of uptake to exceed normal in these cells indicates that their transformed behavior is not attributable to excessive sugar uptake per se.