[Phenotype expression and function of antigen presenting cells in huaman gammadelta T cells activated by peptide antigen from Mycobacterium tuberculosis].

Aim: To explore whether the human peripheral gammadelta T cells stimulated by polypeptide heat resistant antigen from Mycobacterium tuberculosis (Mtb-HAg) express phenotype and have the fuction of antigen presentation.

Methods: The monocytes isolated by adhesion method from peripheral blood mononuclear cells (PBMCs) were cultured with GM-CSF, IL-4 and induced into the mature dendritic cells by adding LPS. PBMCs were stimulated with Mtb-HAg and IL-2 to expand predominantally gammadelta T cells that were further purified by flow sorting. The pure T cells were isolated from PBMCs using adhesion revomal and nylon column method, labeled with CFSE, and cultured in alone with Mtb secretory antigen (Mtb-SAg), in monocytes with Mtb-SAg, or with Mtb-SAg pre-pulsed dendritic cells or Mtb-HAg activated gammadelta T cells for 11 days. The proliferation of the CD4(+) T cells were measured by flowcytometry. The Mtb-HAg activated gammadelta T cells were incubated with FITC labelled Mtb-SAg for different time, and the ingestion of Mtb-SAg by gammadelta T cells was measured by flowcytometry and observed with laser confocal microscopye.

Results: The expressions of MHC-II and co-stimulatory molecules CD80 and CD86 on gammadelta T cells that activated by Mtb-HAg marketly incrased in comparison with that on the resting gammadelta T cells. The expanded cell counts and proliferation index of the pure naïve T cells that induced by Mtb-SAg pretreated activated gammadelta T cells were similar to that induced by mature DC. By using flowcytometer and laser confocal microscope, FITC labellaed Mtb-SAg was ingested by the activated gammadelta T cells.

Conclusion: gammadelta T cells stimulated by polypeptide Mtb-HAg express the phenotype of professional antigen-presenting cells and they are able to present Mtb-SAg to naïve T cells to induce the proliferation of CD4(+) T cells.