CD4 and chronic obstructive pulmonary disease: Our findings that CD4+ and CD8+ effector memory cells are increased in the lungs of COPD patients are congruent with earlier work showing an increase in effector memory cells in the lungs of COPD patients compared to peripheral blood;33 however, we extended these findings to show increased numbers of these cells in the lungs of COPD patients relative to non-diseased control subjects.