Programmed cell death of B lymphocytes is induced by ligation of integrin-associated protein [CD47]

As part of the Immunoglobulin [Ig] superfamily, the transmembrane glycoprotein CD47 forms a signalling complex with the CD23 receptor alphavbeta3 integrin, which stimulates cytokine synthesis and controls inflammation by regulating leukocyte activation and the phagocytosis of aging apoptotic leukocytes. To investigate the effects of anti-CD47 antibodies on a range of cell types at varying stages of development. Using flow cytometric analysis, KMS11 and H929 human B lymphocyte multiple myeloma cell lines were used to study the expression of CD47 and alphavbeta3 integrin as a means to explore the factors relating to the induction and resistance to apoptosis. We found that both cell lines expressed high levels of CD47, with KMS11 cells expressing more than H929 cells. CD47 stimulated an increase in apoptosis in both KMS11 and H929 cells with the preponderance being late apoptotic, dying cells. Ligation of CD47 via the soluble phase was crucial for apoptosis to take place. These results provided an insight into the apoptotic mechanisms involved in the control of inflammation surrounding the activation and phagocytosis of leukocytes. In conclusion, further analysis is required to elucidate the complete signaling cascade responsible for this proliferative effect. Induction of apoptosis via CD47 stimulation appears to occur in the absence of CD47's signaling complex partner, alphavbeta3 whether or not apoptosis occurs, appears to be dependent upon the cell type and also the way CD47 is engaged

Prevalence, antibiotic susceptibility pattern and production of extended-spectrum beta-lactamases amongst clinical isolates of Klebsiella pneumoniae at armed forces hospital in Saudi Arabia

The aim of this descriptive study was to determine the prevalence of Klebsiella pneumoniae from different clinical specimens, their antibiotic susceptibility pattern and the extended-spectrum b-lactamase [ESBL] production among such isolates at Armed Forces Hospital, Al-Kharaj, Saudi Arabia, from November, 2004 to October, 2007. A total of 328 isolates of K. pneumoniae recovered from 8152 different specimens were studied for ESBL production and antimicrobial susceptibility. The prevalence of K. pneumoniae was 4% [328/8152]. We observed a high percentage of K. pneumoniae resistant to ampicillin [100%] and tetracycline [92%]. The prevalence of ESBL-producing K. pneumoniae was found to be 10.4% [34/328]. The ESBL-producing strains were mostly from aspirates [25%] followed by sputum [20%] and blood [18.2%]. These ESBLproducing isolates were highly resistant to gentamicin and ciprofloxacin. All isolates were susceptible to imipenem. Our findings demonstrate a high percentage of ESBL-producers among clinical isolates of K. pneumoniae and a high rate of multidrug resistance. Continued infection control measures and prudent use of antimicrobial agents are essential in reducing the spread of multi-resistant ESBL-producing K. pneumoniae