CD34+ selection of autologous peripheral blood stem cells for transplantation following sequential cycles of high-dose therapy and mobilisation in multiple myeloma

A potential problem of autologous transplantation in the treatment of multiple myeloma (MM) is the infusion of tumor cells. CD34+ selection has been used to purge autografts in MM and it is also possible to reduce tumour cell contamination of autografts by cytotoxic drug therapy prior to peripheral blood stem cell (PBSC) collection. To evaluate the effectiveness of a protocol combining multiple cycles of high-dose therapy and CD34+ selection to reduce tumour contamination of PBSC autografts, 34 MM patients were entered on a treatment schedule comprising two sequential cycles of mobilisation, CD34+ selection, and transplantation following high-dose therapy. In the second cycle of mobilisation there was a five-fold reduction in tumour contamination of the stem cell harvest (0.5 x 106/kg) compared with the first cycle (2.5 x 106/kg). In the 97 CD34+ selection procedures performed a median of 185 x 108 mononuclear cells (MNC) were processed yielding a median of 0.98 x 108 CD34+-enriched cells. CD34+ cells were enriched 68-fold from 1. 3% to 88.6%. The median yield of CD34+ cells was 42.2%. Following CD34+ selection the tumour cell contamination of the leukapheresis product was reduced by a median of 2.7 logs. This study demonstrates that in multiple myeloma a significant reduction in the malignant contamination of stem cell autografts can be achieved by combining the in vivo purging effect of cytotoxic therapy with in vitro purging by CD34+ selection.P G Dyson, N Horvath, D Joshua, L Barrow, N G Van Holst, R Brown, J Gibson and L B T

Campylobacter jejuni cell lysates differently target mitochondria and lysosomes on HeLa cells

Campylobacter jejuni is the most common cause of bacterial gastroenteritis in humans. The synthesis of cytolethal distending toxin appears essential in the infection process. In this work we evaluated the sequence of lethal events in HeLa cells exposed to cell lysates of two distinct strains,C. jejuniATCC 33291 andC. jejuniISS3. C. jejunicell lysates (CCLys) were added to HeLa cell monolayers which were analysed to detect DNA content, death features, bcl-2 and p53 status, mitochondria/lyso-somes network and finally, CD54 and CD59 alterations, compared to cell lysates ofC. jejuni11168HcdtA mutant. We found mitochondria and lysosomes differently targeted by these bacterial lysates. Death, consistent with apoptosis for C. jejuniATCC 33291 lysate, occurred in a slow way ([48 h); concomitantly HeLa cells increase their endolys-osomal compartment, as a consequence of toxin internali-zation besides a simultaneous and partial lysosomal destabilization.C. jejuniCCLys induces death in HeLa cells mainly via a caspase-dependent mechanism although a p53 lysosomal pathway (also caspase-independent) seems to appear in addition. In C. jejuniISS3-treated cells, the p53-mediated oxidative degradation of mitochondrial components seems to be lost, inducing the deepest lysosomal alterations. Furthermore, CD59 considerably decreases, suggesting both a degradation or internalisation pathway. CCLys-treated HeLa cells increase CD54 expression on their surface, because of the action of lysate as its double feature of toxin and bacterial peptide. In conclusion, we revealed thatC. jejuniCCLys-treated HeLa cells displayed different features, depending on the par-ticular strain