final program.qxd - Parallels Plesk Panel

PP 2.13
Assessing the Contribution of CD8+ T Cells among TB Case-Contact Cohort Using
Fresh EX-VIVO Elispot Readouts
Lugos MD, Hammond AS, Adegbola RA and Brookes RH
MRC Laboratories, The Gambia
The IFN-γ secreting T cells have been reported to play a central role in protective
immunity against TB. Whilst the role of CD4+ T cells is crucial, recent evidence suggests
IFN-γ secreting CD8+ T cells may also have a key role in control of latent or chronic MTB
infection.
Our objective is to assess the contribution of CD8 + T cells in TB immune response using
ELISPOT readouts from TB Case-Contact cohort.
We employed novel tetrameric antibody cocktail (RosetteSep) to deplete CD8 cells
directly from whole blood. Fresh ex vivo ELISPOT assay was carried out using depleted
and undepleted PBMC from TBCC cohorts to determine the proportion of circulatory
effector T cells. Flow cytometry was used to determine the percentage purity of cells
depleted.
Results show variable drops in PBMC count ranging from 5.26 - 77.14%. Despite this, a
98% depletion success was obtained for CD8+ T cells, while 59.4% enrichment was
observed for the CD4 fragment. Further, we observed a comparable increase in IFN--γ
producing cell frequencies as an indication of enhanced CD4 response. Responder
frequencies of CD8 depleted fraction showed a decreased trend, with those responding to
ESAT-6 having a higher count among cases than contacts.
We therefore conclude that TB cases tend to show more of CD8 immune responses.
Hence, the appearance of CD8+ T cell response could be used as a marker for progression
to disease amongst the infected TB contacts.
“ Focusing FIRST on PEOPLE “ 132 w w w . i s h e i d . c o m