Rapid kinetics of serum IgA after vaccination with Prevnar®13 followed by Pneumovax®23.

Streptococcus pneumoniae is a causative agent of community-acquired pneumonias. The recommendations of the 2012 Advisory Committee on Immunization Practices include vaccination with Prevnar®13 (protein-polysaccharide conjugate vaccine; PCV), followed by Pneumovax®23 (polysaccharide-based vaccine; PSV) in adults 65+ or the immunocompromised. In this experiment, a group of 4 healthy volunteers were vaccinated with PCV followed by PSV 60 days later. ELISAs were optimized to study kinetics of IgA, IgM, total IgG and its four subclasses against 14 polysaccharides of the pneumococcal capsule. Although this is a small sample, results from volunteers consistently showed that rapid induction of monomeric IgA followed by rapid decline is typical for both vaccines. IgA was not detected after PSV vaccination in those serotypes present in PCV, suggesting the population of B cells secreting IgA is not renewed within 60 days of activation by PCV. In contrast to mice, human neutrophils expressed a functional receptor for the constant region of monomeric IgA. Thus, the role of IgA early in the human immune response should be further investigated.

Dispermic chimerism identified during HLA typing for stem cell transplantation.

BACKGROUND: Chimerism is defined as the presence of two genetically distinct cell populations in an organism. Few cases of phenotypically normal dispermic chimeras have been reported and most showed abnormalities on blood typing. CASE REPORT: A 32-year-old man was diagnosed with acute myelomonocytic leukemia. He clearly typed as group A, D-. No abnormalities of sexual development were identified on multiple physical exams, previous exploratory surgery, or CT scans. Molecular HLA typing (sequence-specific primers) in preparation for stem cell transplant showed the patient to have three HLA-B* and three HLA-Cw* alleles. Initial serologic HLA typing reported two haplotypes, but on subsequent review reactions for a third HLA-B antigen that were initially deemed to be false-positive reactions were identified. Two of 10 microsatellite short tandem repeat (STR) loci also showed three distinct alleles in blood and buccal samples. In all studies the third allele was attributable to a dual paternal contribution. CONCLUSION: This case represents dispermic chimerism, with one maternal and two paternal haplotypes variably distributed throughout body tissues in a phenotypically normal man without abnormalities in blood typing. The presence of additional alleles that may have been undetected or dismissed by serologic typing should be carefully investigated and verified by molecular techniques. Molecular HLA typing may increase the accurate identification of phenotypically normal chimeras and aid in selecting proper donors for transplantation to reduce graft-versus-host disease and transplant rejection in these patients.

High-density single-nucleotide polymorphism maps of the human genome.

Here we report a large, extensively characterized set of single-nucleotide polymorphisms (SNPs) covering the human genome. We determined the allele frequencies of 55,018 SNPs in African Americans, Asians (Japanese-Chinese), and European Americans as part of The SNP Consortium's Allele Frequency Project. A subset of 8333 SNPs was also characterized in Koreans. Because these SNPs were ascertained in the same way, the data set is particularly useful for modeling. Our results document that much genetic variation is shared among populations. For autosomes, some 44% of these SNPs have a minor allele frequency > or =10% in each population, and the average allele frequency differences between populations with different continental origins are less than 19%. However, the several percentage point allele frequency differences among the closely related Korean, Japanese, and Chinese populations suggest caution in using mixtures of well-established populations for case-control genetic studies of complex traits. We estimate that approximately 7% of these SNPs are private SNPs with minor allele frequencies <1%. A useful set of characterized SNPs with large allele frequency differences between populations (>60%) can be used for admixture studies. High-density maps of high-quality, characterized SNPs produced by this project are freely available.