CD44 expression differs concerning prognostically distinct CLL subtypes High expression of CD44 on CLL cells has been related with adverse clinical characteristics. On the other hand, the correlation among CD44 expression plus the more a short while ago defined prognostic subtypes of CLL and specifically with IgVH mutational status or ZAP70 expression has not been described. Implementing flow cytometry, we quantified CD44 expression in CLL cells and in B lymphocytes obtained from healthful donors. Surface CD44 was detected on all CLL cells at the same time as on ordinary B cells. The degree of CD44 expression was extremely variable amid distinct CLL samples and correlated with IgVH mutational status. To quantify the expression of CD44 we calculated the ratio amongst the indicate fluorescent intensity of CD44 staining divided through the MFI on the corresponding isotype staining. The expression of CD44 was significantly greater in U CLL cells than in M CLL cells or in regular B cells. In contrast, MCLL cells had reduce CD44 expression than usual B cells.
CD44 induces homotypic aggregation and protects CLL cells from spontaneous apoptosis To investigate the effect of CD44 signaling on CLL cells, we 1st stimulated PBMCs from CLL individuals that has a monoclonal antibody that binds on the extracellular domain of CD44. CD44 engagement triggered homotypic aggregation of the CLL cells, which can be a common result of diverse exogenous stimuli that activate cells read full article or modulate cell adhesion. CLL cells aggregated within minutes and clustered into clumps containing huge numbers of cells. These clumps had been characterized by strong cell cell interactions and have been problematic to dissociate. As expected, the induction of homotypic aggregation was temperature dependent and entirely blocked at four C, steady with all the necessity of intracellular signaling for the aggregation to occur. These information indicate the monoclonal antibody towards CD44 acts as an agonist and will set off an intracellular signal. Engagement of CD44 prevented CLL cells from undergoing spontaneous apoptosis and extended the survival of leukemic cells in vitro.
A survival benefit for CD44 stimulated cells was apparent as early as 24 hours soon after stimulation and increased more with prolonged culture. We chose 72 hours of culture to quantify the result of CD44 stimulation in the more substantial variety of samples. This time point appeared best since on normal, 50% of unstimulated CLL cells remained viable soon after three days of culture. All samples with CD44 stimulation showed significantly improved viability than handle samples. On article source normal, CD44 stimulated CLL cells had a 46% expand in viability above the corresponding unstimulated management cells. All these measurements had been executed in peripheral blood mononuclear cells from CLL patients containing a higher proportion of leukemic cells, often in excess of 90%.