Skewed distribution of circulating activated natural killer T (NKT) cells in patients with common variable immunodeficiency disorders (CVID)

Abstract

Common variable immunodeficiency disorder (CVID) is the commonest cause of primary antibody failure in adults and children, and characterized clinically by recurrent bacterial infections and autoimmune manifestations. Several innate immune defects have been described in CVID, but no study has yet investigated the frequency, phenotype or function of the key regulatory cell population, natural killer T (NKT) cells. We measured the frequencies and subsets of NKT cells in patients with CVID and compared these to healthy controls. Our results show a skewing of NKT cell subsets, with CD4+ NKT cells at higher frequencies, and CD8+ NKT cells at lower frequencies. However, these cells were highly activated and expression CD161. The NKT cells had a higher expression of CCR5 and concomitantly expression of CCR5+CD69+CXCR6 suggesting a compensation of the remaining population of NKT cells for rapid effector action.

Figure 1. Expression of NKT cells in peripheral blood.

(A) Representative flow cytometric analyses on PBMC, lymphocytes, CD3+ T cells and Vα24+Vβ11+ for NKT cells. (B) Fluorescence minus one (FMO) was used for gate strategy for CXCR6, CCR5 and CD69 in NKT cells. (C) Representative flow cytometric analyses on NKT cells in CVID patients. Comparisons among groups were carried out using the Mann-Whitney non-parametric test.

Figure 2. Percentage of activation, chemokine receptors in NKT cells.

(A) Percentage of chemokine receptor CCR5 in NKT cells gate (Vα24+Vβ11) in representative healthy subject and CVID patient (p<0.0001). (B) Percentage of chemokine receptors CXCR6, CCR5 and CD69 marker in NKT cells (p<0.001). (C) Percentage of chemokine receptor CCR5 and CD69 marker in NKT cells (p<0.001). Comparisons among groups were carried out using the Mann-Whitney non-parametric test.

Figure 3. Subsets of NKT cells from CVID patients.

(A) Percentage of CD4 marker in NKT cells (left) (p = 0.0055). (B) Absolute number of CD4 marker in NKT cells (middle). (C) Representative flow cytometry dot plot of CD4 marker (right). (D) Percentage of CD8 marker in NKT cells (left) (p = 0.011). (E) Absolute number of CD8 marker in NKT cells (middle) (p = 0.002). (F) Representative flow cytometry dot plot of CD8 marker (right). (G) Percentage of CD161 marker in NKT cells (left). (H) Absolute number of CD161 marker in NKT cells (middle). (I) Representative flow cytometry dot plot of CD161 marker (right).

Figure 4. Subsets of NKT cells.

(A) Percentage of CD161, CD8 and CD4 markers in NKT cells (p = 0.0145), (B) Percentage of CD4 and CD161 marker in NKT cells (p = 0.001). (C) Percentage of CD8 and CD161 markers in NKT cells (p = 0.0004).