Immunodominance among EBV-derived epitopes restricted by HLA-B27 does not correlate with epitope abundance in EBV-transformed B-lymphoblastoid cell lines.

Using synthetic peptides, the HLA-B27-restricted CTL response to EBV in asymptomatic virus carriers has been mapped to four epitope regions in EBV latent cycle Ags. One of these peptide-defined epitopes (RRIYDLIEL) tends to be immunodominant and is recognized in the context of all three B27 subtypes studied, B*2702, B*2704, and B*2705. The other peptide-defined epitopes induce responses only in the context of one subtype, the immunogenic combinations being RRARSLSAERY/B*2702, RRRWRRLTV/B*2704, and FRKAQIQGL/B*2705. We used immunoaffinity chromatography to isolate the naturally presented viral peptides associated with these MHC class I molecules on the surface of EBV-transformed B-LCL. Using CTL reconstitution assays in conjunction with mass spectrometry, we established that the naturally processed and presented peptides are identical with the previously identified synthetic sequences. Despite the subtype-specific immunogenicity of three of the four epitopes, all four epitope peptides were found in association with each of the three different HLA-B27 subtypes. Indeed, those peptides that failed to induce a response in the context of a particular HLA-B27 subtype were frequently presented at greater abundance by that subtype than were the immunogenic peptides. Furthermore, among the peptides that did induce a response, immunodominance did not correlate with epitope abundance; in fact the immunodominant RRIYDLIEL epitope was least abundant, being present at less than one copy per cell. The relationship of this unexpected finding to the persistence of EBV is discussed.

Biochemical identification of a mutated human melanoma antigen recognized by CD4(+) T cells.

CD4(+) T cells play a critical role in generating and maintaining immune responses against pathogens and alloantigens, and evidence suggests an important role for them in antitumor immunity as well. Although major histocompatibility complex class II-restricted human CD4(+) T cells with specific antitumor reactivities have been described, no standard method exists for cloning the recognized tumor-associated antigen (Ag). In this study, biochemical protein purification methods were used in conjunction with novel mass spectrometry sequencing techniques and molecular cloning to isolate a unique melanoma Ag recognized by a CD4(+) tumor-infiltrating lymphocyte (TIL) line. The HLA-DRbeta1*0101-restricted Ag was determined to be a mutated glycolytic enzyme, triosephosphate isomerase (TPI). A C to T mutation identified by cDNA sequencing caused a Thr to Ile conversion in TPI, which could be detected in a tryptic digest of tumor-derived TPI by mass spectrometry. The Thr to Ile conversion created a neoepitope whose T cell stimulatory activity was enhanced at least 5 logs compared with the wild-type peptide. Analysis of T cell recognition of serially truncated peptides suggested that the mutated amino acid residue was a T cell receptor contact. Defining human tumor Ag recognized by T helper cells may provide important clues to designing more effective immunotherapies for cancer.

Psychopathy and conduct problems in children: II. Implications for subtyping children with conduct problems.

OBJECTIVE: To test whether the presence of callous and unemotional (CU) traits designates a unique subgroup of children with conduct problems that corresponds more closely to adult conceptualizations of psychopathy. METHOD: A clinic-referred sample of 120 children between the ages of 6 and 13 years were assessed using parent and teacher ratings of CU traits, as well as parent and teacher report on a structured interview assessing oppositional defiant disorder (ODD) and conduct disorder (CD) symptoms. RESULTS: A cluster analysis of the ratings of CU traits and ODD/ CD symptoms revealed four clusters of children, two of which had high rates of ODD and CD symptoms. One of these conduct problem clusters also exhibited high levels of CU traits (n = 11). These children had a greater number and variety of conduct problems, a stronger history of police contacts, and a stronger parental history of antisocial personality disorder, despite being of higher intelligence than other children with significant conduct problems (n = 29). CONCLUSION: The presence of CU traits with significant conduct problems seems to designate a unique subgroup of antisocial children who show a very severe pattern of antisocial behavior and who correspond more closely to adult conceptualizations of psychopathy.

Heritability of mastitis score in pacific northwest dairy herds.

Dairy Herd Improvement Association records of Holsteins in the Pacific Northwest were used to estimate heritabilities and correlations between milk yield, fat yield, fat percentage, and mastitis score. Effects of sire and lactation number were important for all traits except lactation number for fat percentage. Average mastitis score as well as frequency of elevated tests increased with parity. Paternal half-sister analysis showed that heritabilities of milk yield, fat yield, and fat percentage decreased with age averaging .33, .28, and .47 for first records and .29, .20, and .33 for last records. Heritability of mastitis score increased slightly with age averaging .10 for first records and .11 for last records. Milk yield and fat yield showed small genetic correlations of .05 and .07 with mastitis score. Pearson and Spearman correlation coefficients were computed between regressed least square estimates for sires derived for six independent sets of daughters. Pearson correlations between mastitis scores of first and last lactations were .19 and .34, whereas corresponding average Spearman correlations were .11 and .29. These low correlations between sire rankings in different data sets correspond closely with the low heritabilities for mastitis score.