The Number and Proportion of V 9V 2 T Cells Rise Significantly in the Peripheral Blood of Patients After the Onset of Acute Coxiella burnetii Infection

We conducted serial studies on peripheral blood lymphocytes from four patients with acute Coxiella burnetii infection. These studies revealed that the proportion of gammadelta T cells in these patients significantly increased after the onset of disease (mean, 16%; range, 13%-30%) as compared with that in five healthy controls (mean, 4%; range, 0.5%-7%; P < .0055) and that in five controls with pneumonia (mean, 2%; range, 1%-3%; P < .0014). Most of the gammadelta T cells from these patients expressed the Vgamma9 Vdelta2 gene product. During the acute phase of disease, most gammadelta T cells expressed the activation marker human leukocyte antigen DR but not CD25. During this phase, gammadelta T cell activation was higher than alphabeta T cell activation. Our findings indicate that gammadelta T cells are predominantly involved in the acute immune response to C. burnetii.