Isolation of CD4+ T cells from murine lungs: a method to analyze ongoing immune responses in the lung.

The regulation of the cellular immune response in lung diseases is not yet fully understood. Isolating different subsets of immune cells directly from the lung is therefore an indispensable method of gaining detailed knowledge on the function of these cells in this organ. This protocol describes a method of isolating and magnetically labeling CD4+ lung T cells, which are then loaded and retained on the column while all other cells run through it (positive selection). The yield of this isolation is approximately 5 x 10(5) to 1.5 x 10(6) CD4+ cells from a murine lung. These cells can be further investigated by several methods such as flow cytometry, western blot analysis, RT-PCR, immunostaining and ELISA. In addition, lung CD4+ T cells alone or along with other immunologically important cells such as CD8+ T cells and T regulatory cells can be adoptively transferred into immune-deficient mice, and can influence important local parameters. This protocol can be completed in approximately 4 h 20 min.