Heterogeneity of VH-JH gene rearrangement patterns: an insight into the biology of B cell precursor ALL.

Oligoclonal B cell proliferation, as defined by the presence of more than one leukemic clone, has been detected in approximately 20% to 30% of patients with acute lymphoblastic leukemia (ALL) using PCR or Southern blotting. An accurate assessment of these populations is required to avoid false negative measurements of minimal residual disease (MRD) in follow-up bone marrow (BM) samples of ALL patients. In this study, we analysed 29 ALL patients with two or more immunoglobulin heavy (IGH) chain gene rearrangements in the presentation samples using IGH fingerprinting PCR and sequence analysis. Thirty-nine (51%) of 76 sequences (from 15 patients), shared no VNDNJ homology (ie different CDR3 regions). In the remaining 14 patients, at least two related VH sequences were identified in each patient (identical DNJ sequences). Numerical abnormalities of chromosome 14 was detected in 10 patients. Eight patients were analysed at presentation and relapse. In four of them, expansion of a minor presentation-clone was detected at relapse while the major presentation clone disappeared, confirming 'subclonal evolution'. Finally, in our cohort of patients, the presence of related or unrelated IGH clones did not influence overall survival.

Immunoglobulin heavy-chain gene rearrangement in adult acute lymphoblastic leukemia reveals preferential usage of J(H)-proximal variable gene segments.

The aim of this study was to characterize individual-segment and overall patterns of V(H) gene usage in adult B-lineage acute lymphoblastic leukemia (ALL). Theoretical values of V(H) segment usage were calculated with the assumption that all V(H) segments capable of undergoing rearrangement have an equal probability of selection for recombination. Leukemic clones from 127 patients with adult B-lineage acute leukemias were studied by fingerprinting by means of primers for the framework 1 and joining segments. Clones from early preimmune B cells (245 alleles identified) show a predominance of V(H)6 family rearrangements and, consequently, do not conform to this hypothesis. However, profiles of V(H) gene family usage in mature B cells, as investigated in peripheral blood (6 samples), B-cell lymphomas (36 clones) and chronic lymphocytic leukemia (56 clones), are in agreement with this theoretical profile. Sequence analyses of 64 V(H) clones in adult ALL revealed that the rate of V(H) usage is proportional to the proximity of the V(H) gene to the J(H) locus and that the relationship can be mathematically defined. Except for V(H)6, no other V(H) gene is excessively used in adult ALL. V(H) pseudogenes are rarely used (n = 2), which implies the existence of early mechanisms in the pathway to B-cell maturation to reduce wasteful V(H)-(D(H))-J(H) recombination. Finally, similar to early immunoglobulin-H rearrangement patterns in the mouse, B cells of ALL derive from a pool of cells more immature than the cells in chronic lymphoid B-cell malignancies.

Properties of tissue from around cemented joint implants with erosive and/or linear osteolysis.

Levels of bone remodeling agents were measured in conditioned media from cultures of periprosthetic pseudosynovial membranes and related to the radiographic features of the failed joint implants. Radiographs of both cemented hip (n = 28) and cemented knee (n = 11) implants were examined and the pattern of radiolucency was classified as erosive linear, or mixed. Similar levels of interleukin-1-beta (IL-1 beta), interleukin-6, tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta-1, and prostaglandin E2 (PGE2) were found in pseudosynovial membrane conditioned media from all 3 groups of hips and the knee group (all linear). Significant correlations were evident only between PGE2 and TNF-alpha levels in the linear hip group and PGE2 and IL-1 beta levels in the knee group. A close correlation was found between IL-1 beta and TNF-alpha in both linear and erosive hips. It is suggested that coregulation of these bone remodeling agents differs with the radiographic appearance of the failed joint implants. As all the implants were cemented and the results contrast with those of others obtained with pseudosynovial membrane conditioned media from cementless implants, it is considered that cement critically influences the process of implant failure.

Osteolytic properties of the synovial-like tissue from aseptically failed joint prostheses.

Relationships were found between the bone-resorbing ability of conditioned media (CMs) from culture of peri-prosthetic tissues and their levels of bone-remodelling agents. Bone-resorbing activity was measured by 45Ca release from pre-labelled mouse calvaria and 23 of 40 CMs exhibited bone-resorbing activity. Cytokine and prostanoid levels in the CMs were measured by immunoassay, and the levels of interleukin (IL)-1 beta, IL-6, tumour necrosis factor alpha (TNF alpha) and prostaglandin E2 (PGE2) correlated with each other, except for the latter two. Significantly higher levels of IL-6 were present in those CMs with bone-resorbing activity than in those without, and a similar pattern was observed for PGE2 and IL-1 beta. However, some CMs with high levels of IL-1 beta, IL-6, TNF alpha and PGE2 failed to induce resorption, whereas a few CMs with low levels of these agents induced resorption. Moreover, neither dialysis of CMs nor addition of neutralizing antisera to IL-1 alpha and IL-1 beta to CMs, either alone or in combination, reduced the bone-resorbing activity of the CMs. It is considered that these agents may act synergistically to mediate osteolysis around failed joint implants, but that other unidentified bone-resorbing agent(s) must be involved.

Analysis of cell types and mediator production from tissues around loosening joint implants.

Quantitative immunophenotypic analysis of cell types present in peri-prosthetic tissue [pseudosynovial membrane (PSM)] from aseptically loose joint implants revealed considerable heterogeneity between tissues from different individuals. The monocyte/macrophage was the commonest leucocyte type; however, its proportion varied widely. T cells normally accounted for approximately 5% of cells, but in a few cases formed > 20% of cells. In all cases, there was a high ratio of CD4 to CD8 cells. PSM leucocytes were activated in most PSMs as judged by surface expression of CD23, CD25 and CD71. Analysis of the proportions of cell types in PSM, OA synovium and RA synovium revealed similarities between the different tissue types. The levels of IL-1, IL-6 and prostaglandin E produced by the PSM were correlated, but only IL-1 and IL-6 levels correlated with markers of the monocyte/macrophage lineage. This result suggests that prostaglandin E is produced in vivo by many PSM cell types.