Mycobacterial molecules, APC function and pathogen recognition receptors (PRR)

SCHIERLOH P; YOKOBORI N; ALEMÁN M; MUSELLA R; CASTAGNINO J; BALDINI M; GEFFNER L; ABBATE E; DE LA BARRERA S; SASIAIN MC

Rio de Janeiro, Brazil

Congreso; 13th International Congress of Immunology. Immuno Rio 2007.; 2007

Sociedade Brasileira de Imunologia (SBI).

In vivo primed NK cells can be found in PF samples from TB patients. In contrast to their peripheral blood counterparts, PF-NK cells are prone to react against Mtb by producing large amount of IFN-g and enhancing CD69 expression. To better describe this locally generated immune mechanism, we evaluated IFN-g+ and CD69+ NK cells by FACS upon in vitro stimulation of PF mononuclear cells (PFMC) with several Mtb encoded molecules and analyzed the requirement of accessory cells and immune receptors. While particulate Mtb was the best inducer of IFN-g+, Mtb-H37Rv whole cell lisate and high molecular size fraction of protein culture filtrate also induced its expression (n=10). By contrast, neither ManLAM nor Peptidoglycan induced a detectable response. Depletion of APC (CD1a-b-c+/CD14+/DC-SIGN+) but not lymphocytes (CD3+/CD20+) reduced the IFN-g production and CD69 expression (p<0.01, n=6). anti-TLR4 and anti-TLR2 partially inhibited IFN-g  expression by PF-NK (p<0.01 and p<0.05 respectively, n=6). Consistently, Pam3Cys(TLR1/2) and LPS(TLR4) agonists upregulated CD69 being not sufficient to induce IFN-g in PF-NK cells, suggesting the involvement of other receptor/s to fulfill the response. Finally, because the APC depletion diminished but not abolished PF-NK response, we asked if direct Mtb recognition by PF-NK took place. Stable conjugates were detected after 10 min of co-incubation of PF-NK with FITC labeled Mtb (p<0.05, n=6). Altogether, our results demonstrate that three factors act in concert in the activation and IFN-  production of PF-NK cells: mycobacterial molecules recognizing innate receptors (PRR), APC co-stimulation and direct NK-Mtb contact.