Differential response of lymphocytes to biofilm derived Streptococcus mitis cells

Abstract

0120 Differential response of lymphocytes to biofilm derived Streptococcus mitis cells
N. PARAHITIYAWA, N. BANDARA, J.Y.Y. YAU, R. WATT, W.K. LEUNG, L. JIN, and L.P. SAMARANAYAKE, The University of Hong Kong, Hong Kong SAR, China

Biofilms, or surface attached microbial communities, are responsible for many localized and systemic diseases especially among immunocompromised hosts. Cells dislodged from such biofilms may enter the systemic circulation and have the propensity to invade distant organs and tissues. It is well recognised that biofilms are highly resistant to antimicrobials compared with their free-floating planktonic counterparts. Yet, how the cellular defences of the body interact with biofilm derived bacteria, is ill understood.

Objectives: This preliminary study compared the response of peripheral blood lymphocytes (PBL) to the biofilm derived (BF) and, planktonic cells (PC) of Streptococcus mitis, an organism commonly seen in bacteraemic states.

Methods: Human PBL were harvested from two systemically healthy adults using the Ficoll Paque layering method. Biofilms and planktonic cultures of Streptococcus mitis were grown in polystyrene well plates and culture tubes under standard conditions. The response of harvested lymphocytes to bacterial assault was measured at different time points using the XTT reduction assay.

Results: Biofilm growth was evident at 24 and 48 hours. At both time points, the XTT reduction response of PBL-BF and PBL-PC was significantly higher than PBL alone. For the 24 hour old cultures, the time-curve for XTT reduction assays showed that PBL-BF response was consistently lower than that for PBL-PC. As time passed the activity reached a plateau but the PBL –BF endpoint activity remained lower than that of PBL-PC. The response was reversed with 48 hour grown cultures where PBL-BF response was higher than PBL-PC response.

Conclusion: The data from this pilot experiment suggests that the biofilm constituent cells, particularly the young (24 hrs), stimulate PBL to a lesser extent than the older biofilm cells or their planktonic counterparts. This may explain to some degree their sluggish clearance and persistence in the bloodstream.

Full text

0120 Differential response of lymphocytes to
biofilm derived Streptococcus mitis cells
N. PARAHITIYAWA, N. BANDARA, J.Y.Y. YAU, R. WATT, W.K. LEUNG, L. JIN,
and L.P. SAMARANAYAKE, The University of Hong Kong, Hong Kong SAR, China
Biofilms, or surface attached microbial communities, are responsible for many localized
and systemic diseases especially among immunocompromised hosts. Cells dislodged
from such biofilms may enter the systemic circulation and have the propensity to invade
distant organs and tissues. It is well recognised that biofilms are highly resistant to
antimicrobials compared with their free-floating planktonic counterparts. Yet, how the
cellular defences of the body interact with biofilm derived bacteria, is ill understood.
Objectives: This preliminary study compared the response of peripheral blood
lymphocytes (PBL) to the biofilm derived (BF) and, planktonic cells (PC) of
Streptococcus mitis, an organism commonly seen in bacteraemic states.
Methods: Human PBL were harvested from two systemically healthy adults using the
Ficoll Paque layering method. Biofilms and planktonic cultures of Streptococcus mitis
were grown in polystyrene well plates and culture tubes under standard conditions. The
response of harvested lymphocytes to bacterial assault was measured at different time
points using the XTT reduction assay.
Results: Biofilm growth was evident at 24 and 48 hours. At both time points, the XTT
reduction response of PBL-BF and PBL-PC was significantly higher than PBL alone.
For the 24 hour old cultures, the time-curve for XTT reduction assays showed that PBL-
BF response was consistently lower than that for PBL-PC. As time passed the activity
reached a plateau but the PBL –BF endpoint activity remained lower than that of PBL-
PC. The response was reversed with 48 hour grown cultures where PBL-BF response
was higher than PBL-PC response.
Conclusion: The data from this pilot experiment suggests that the biofilm constituent
cells, particularly the young (24 hrs), stimulate PBL to a lesser extent than the older
biofilm cells or their planktonic counterparts. This may explain to some degree their
sluggish clearance and persistence in the bloodstream.
Seq #10 - Poster Presentation
11:00 AM-12:30 PM, Friday, October 10, 2008
Back to the Scientific Groups Program
Back to the 22nd International Association for Dental Research (SEA Division) & 19th
South East Asia Association for Dental Education (October 8-10, 2008)
Top Level Search