Tobacco Documents Online

TIiI: COUNCIL FOR TOBACCO RESEARCH-U.S.A., INC. TO: Dr. S. C. Sommers and Staff Site Visitors: Drs. Ford and Stone Re: Site visit September 1984 with B. M. Peterlin, M.D., University of California, San Francisco. Grant No. 1593R1 entitled, "Biology and Molecular Biology of the Differentiation of a Human Monocytoid Cell Line" Discussion The aim of this project is the elucidation of biological events in the genesis of the mature macrophage (i.e. one capable of presenting antigen to T cells). The model system studied is the differentiation of the immature monocytoid cell (N-937 cell line) to the mature macrophage which, among other characteristics, now expresses HLA.DR antigens on the cell membrane. Peterlin's working hypothesis is that the gene(s) involved are hypermethylated and so cannot be expressed. Therefore, hypomethylation must be a first step, followed by a second step in which transcription of the now-available gene(s) is promoted. 5-azacytidine (a cytidine analogue) cannot be methylated and cells cultured in the presence of 5-AZA incorporate it into their DNA. Peterlin employs 5-AZA as his first signal. The second signal is supplied by (a) the medium from Con A-activated T cells or (b) interferon- b. Dr. Peterlin is particularly interested in the molecular genetic aspects, and his focus is upon the action of these signals in the transcription and regulation of the HLA-DR gene(s). That is: hypermethylated less methylation IFN-J DR antigen (which can be immunoprecipitated) Methylation patterns of the o~ and P chains for the HLA-DR DNA region are being undertaken, as well as base-sequence analysis before and after each (or both) of the signals. Peterlin hopes to characterize and map the promotion (and enhancing) regions initiated by Y-interferon. Peterlin is working to transfect inactive macrophage with HLA.DR genes and to demonstrate that the product (i.e. the DR antigen) can now be found, by immuno- chemical techniques, on the cell surface, and that such cells are now active in presenting antigen to appropriate T cells. Conclusion A bright young investigator in a complex, but exciting and relevant field. Progress appears to be satisfactory. Would suggest continued CTR support. DF/DS 0