Clinical characteristics of human lymphoid tissue inducer cells isolated from tonsils

Abstract

Lymphoid tissue inducer (LTi) cells, found in mouse secondary lymphoid tissue, influence the development of lymph nodes and Peyer’s patches, and play critical roles in lymphoid tissue development and maintenance of CD4 dependent immune responses. A number of attempts have been made to search for the human equivalent of murine LTi cells. However, the presentation of human LTi-like cells in various conditions has not been elucidated yet. Therefore, this study was designed to explore the relationship between LTi-like cells and the patients’ clinical and immunological conditions. Initially, the quantity of CD117+CD3-CD56- LTi-like cells separated from human tonsil tissue was analyzed in conjunction with clinical factors (sex, age, height, weight, tonsil size, allergy, IgE and eosinophils), and T cells and B cells. Then, as the importance of CD127+ expression was reported, CD117+CD3-CD56-CD127+ LTi cells were also evaluated along with clinical factors and T cells. The expression of OX40L and IL-22 on CD117+CD3-CD56- cells isolated from tissues afflicted with frequent tonsillitis was also investigated. T-test analysis and Pearson’s correlation coefficient analysis were used to test for statistical significance and a p-value less than 0.05 was considered to be statistically significant. Results show that the presence of frequent tonsillitis showed a correlation to LTi cells. The percentage of naïve CD4 T cells and memory CD4 T cells was significantly related to that of LTi cells. Additionally, the percentage of naïve CD4 T cells and memory CD4 T cells was significantly associated with each other. However, B cells isolated from the palatine tonsil did not show a correlation with LTi cells. The frequent tonsillitis group showed high levels of constitutive OX40L expression on the LTi-like cells, and the production of IL-22 was increased.These results suggest that LTi cells are stimulated and increased by cytokines secreted under conditions of frequent inflammation, and that these increased LTi cells prolong the survival of memory CD4 T cells and increase the number of naïve CD4 T cells which may lead to induction of early intrinsic immunity. Further studies of this sequence should be performed.