Profiling B and T cell immune responses to co-infection of Mycobacterium tuberculosis and hookworm in humans

BACKGROUND Humoral and cellular immune responses play protective roles against Mycobacterium tuberculosis (MTB) infection. However, hookworm infection decreases the immune response to hookworm and bystander antigens. Currently, immune responses to co-infection of MTB and hookworm are still unknown, although co-infection has been one of the public health problems in co-endemic areas of pulmonary tuberculosis (PTB) and hookworm disease. Therefore, it is essential to evaluate B and T cell immune responses to the co-infection. METHODS Seventeen PTB cases co-infected with hookworm, 26 PTB cases, 15 patients with hookworm infection, and 24 healthy controls without PTB or hookworm infection were enrolled in the study. Expressions of CD3, CD4, CD8, CD10, CD19, CD20, CD21, CD25, CD27, CD38, FoxP3, and PD-1 were assessed on B and T cell subsets using multicolor flow cytometry. RESULTS For the B cell (CD19(+)) subsets, naïve B cells (CD10(-)CD27(-)CD21(+)CD20(+)), plasma cells (CD10(-)CD27(+)CD21(-)CD20(-)), and tissue-like memory B cells (CD10(-)CD27(-)CD21(-)CD20(+)) had higher proportions, whilst resting memory B cells (CD10(-)CD27(+)CD21(+)CD20(+)) had lower proportions in the group co-infected with MTB and hookworm as compared to other groups. Frequencies of activated memory B cells (CD10(-)CD27(+)CD21(-)CD20(+)) did not differ among the four groups. For the T cell (CD3(+)) subsets, frequencies of regulatory T cells (CD4(+)CD25(+)Foxp3(+)) and exhausted CD4(+) and CD8(+) T cells (CD4(+)PD-1(+) and CD8(+)PD-1(+)) were higher, and frequencies of activated CD4(+) and CD8(+) T cells (CD4(+)CD38(+) and CD8(+)CD38(+)) were lower in the co-infected group as compared to the other groups. CONCLUSION The change patterns of the cell profile of circulating lymphocytes were indentified in human co-infection of MTB and hookworm, which might indicate that the humoral and cellular immune responses are more suppressed.