A method for treating a respiratory conditions comprises applying peripheral blood from a patient or subject to an apheresis column loaded with a solid support comprising one or more binding reagents capable of specifically binding to a chemokine receptor, optionally the chemokine receptor CCR2, CCR1, CCR3, CCR5, CXCR1, CXCR2 and/or CCR7 immobilized directly or indirectly on the support thus removing one or more chemokine receptor, optionally CCR2, CCR1, CCR3, CCR5, CXCR1, CXCR2 and/or CCR7 expressing cells from the peripheral blood of the patient or subject. Various companion diagnostic methods and useful binding reagents are also described.