The overall goal of this core is to provide genomic typing for immunologically important polymorphic genes and human major histocompatibility antigens. In addition this core will provide reagents and cell lines to be used by the investigators within the projects of this program. All of the research projects within this program project involve components where precise characterization of major histocompatibility antigens (MHC) is of utmost importance. In addition, many of the projects require reagents such as HLA-class I cDNA clones for development of HLA-class I tetrameric product, HLA-class I transfected cells generated with specific HLA alleles and EBV transformed B cell lines that are well characterized for HLA. It is also possible to identify by genomic DNA typing, at least one minor histocompatibility antigen (HA-1) which encodes a HLA-A*0201 restricted polymorphic peptide. It has for many years been hypothesized that NK cells play an important role in the outcome of allogeneic hematopoietic stem cell (HSC) transplantation, but definitive data on these issues are still lacking. The Immunogenetics and Histocompatibility Core Component will provide characterization of KIR phenotypes and/or genotypes for patients and their HSC donors in order to prospectively cumulate such information for inclusion in the analysis of HSC transplant events. The specific functions provided by this core component are: 1. To provide HLA allele level histocompatibility testing of cell lines and volunteer donors who are included in studies within the program project but are not being tested for HLA alleles as part of routine clinical work-up. 2. To provide genomic, low resolution level typing for HLA-class I and class II genes for rapid monitoring of "paternity" of T-cell lines and T-cell clones developed for possible adoptive cell therapy. 3. To identify and isolate full length HLA-class I cDNA clones to be used for development of HLA-class I allele specific antigen presenting cells and for preparation of HLA-class I tetrameric products. 4. To determine the killer cell immunoglobulin-like receptor (KIR) gene phenotype/genotype in patients and their HSC donors. 5. To determine the genotype for the minor histocompat-ibility antigen HA-1 in HLA-A*0201 positive HSC transplant recipients and their donors. The Core will provide essential services in terms of genomic characterization of immunologically important molecules and reagents and cell lines for investigators within the program.