Lymphocyte proliferation assays
This test assumes greater importance in clinical immunology both at a research level and in the clinical laboratories. These tests can be carried out in whole blood that has been anticoagulated so as to permit the use of viable cells. The preferred method is the isolation of the lymphocytes from blood using a density gradient assay method. The anticoagulated blood sample is usually diluted 1:1 with PBS (pH 7.4) and slowly layered over the density gradient solution, which has been prepared so that the cell populations will separate into different layers. Neutrophil and red blood cells are centrifuged to the bottom, while the mononuclear cell population stays in the middle of the gradient. Finally, the serum components and platelets are mainly in areas above and below the mononuclear cells. Once the mononuclear cells are removed from the gradient and washed several times, a relatively pure population of mononuclear cells is obtained.