Age-Related Loss of CD62L Impairs Lymph Node CD4 T Cell Mobilization

ABSTRACT

Impaired pulmonary immunity in the aged is poorly understood. Lymph node recirculation of CD4+ T cells is important for adaptive immunity and depends on CD62L and CCR7. We compared circulatory capacity of CD4+ T cells from young and aged mice in vivo. When congenic CD4+ T cells from young donors were transferred to recipients, the frequencies of donor among endogenous CD4+ T cells was equivalent in sampled tissues. In contrast, those from old donors were five times lower in mediastinal lymph nodes (MLN) than in the spleen. When mixed and transferred to recipients, young CD4+ T cells were four times more abundant in MLN of recipients than old CD4+ T cells. Following pulmonary challenge, old CD4+ T cells were four times less frequent in the MLN than in the spleen. Compared to young, old CD62L₊CD4+ T cells maintained high levels of CCR7 expression but suffered a 50% loss of CD62L. Thus, loss of CD62L, but not CCR7 expression by aged CD4+ T cells is a major factor for impaired lymph node mobilization.

Keywords: