Germ line variable regions that match hypermutated sequences in genes encoding murine anti-hapten antibodies

We asked whether there are germ line immunoglobulin variable (V) segments that match sites of hypermutation in V regions encoding murine antibodies. Murine germ line DNA was probed with a panel of short deoxyoligonucleotides identical in sequence to segments of hypermutated V regions from hybridomas generated in the BALB/c response to the hapten 2-phenyloxazolone (Ox). Germ line sequences that match mutations in both heavy and kappa light chain V regions were identified, and clones of some of these germ line V segments were obtained. Comparison of these clones with hypermutated V regions revealed regions of identity ranging in size from 7 to over 50 nucleotides. In an effort to separate the effects of antigen selection from the mutagenic process, we also searched for matches to a panel of silent mutations in VH regions from germinal center B cells. Fourteen silent mutations occur among a collection of 36 hypermutated VH regions from two separate germinal centers of C57BL/6 mice stimulated with the hapten 4-hydroxy-3-nitrophenyl. Matches to nine of these silent mutations can be found among published sequences of C57BL/6 VH regions of the J558 family. Taken together, these data are consistent with the possibility that a template-dependent mutational process, like gene conversion, may contribute to somatic hypermutation.

Genetic markers in human bone: II. Studies on ABO (and IGH) grouping

A combination absorption-elution, two-dimensional absorption-inhibition procedure was used to determine the ABH antigen composition of a series of human bone specimens of known ABO type that had been aged up to nine months under dry and humid conditions at ambient temperature, 37 degrees C, and 56 degrees C; at ambient temperature in dry and wet soil; and buried in soil outdoors. Grouping data for the separate elution and inhibition testing, as well as for the combination procedure, are given. The combination method was found to be a highly reliable procedure for bone tissue ABH typing. Some data on microbial contaminants of human bone specimens aging in soil, and their effects on ABH typing results, are presented. No direct correlation between the properties of microbial contaminants and specific changes in the ABH antigenic composition of aging bone tissue specimens could be ascertained. Data on IGH antigen determination and on the quantitation of immunoglobulin G (IgG) in human bone tissue extracts indicated that immunoglobulin levels were typically too low to expect routinely successful Gm antigen testing results. However, these factors can sometimes be determined in fresh bone tissue extracts, particularly if the extracts are concentrated.

Genetic markers in human bone: I. Deoxyribonucleic acid (DNA) analysis

Deoxyribonucleic acid (DNA) was isolated from a number of spongy and compact human bone tissue specimens, and the yield was estimated on a "per milligram of starting tissue" basis. DNA was, in addition, isolated from a number of corresponding blood and bone tissue specimens. Spectrophotofluorometry and ethidium bromide visualization on minigels were used to estimate the quantity and degree of degradation of DNA. The DNA from several blood-bone pairs is shown to give concordant restriction fragment length polymorphism (RFLP) typing results by two different typing protocols with five different single-locus probes. DNA from several additional blood-bone pairs is shown to give concordant results for human leucocyte antigen (HLA)-DQ alpha phenotypes following polymerase chain reaction (PCR) amplification and hybridization to specific allele-specific oligonucleotide (ASO) probes, and for the variable numbers of tandem repeats (VNTR) length polymorphisms 3' to the human apolipoprotein B (APOB) gene following PCR amplification with specific primers and analysis of the products by electrophoresis and ethidium bromide visualization.