Effect of storage time on the analysis of lymphocyte subpopulations in pleural effusions

It is not known how long cell surface antigens can be detected on lymphocytes in pleural effusions. Therefore, the lymphocyte subpopulations of 15 native pleural effusions were analyzed after different storage times, at either 4 degrees C or room temperature, using the peroxidase-antiperoxidase adhesive slide assay. No significant differences in the lymphocyte subpopulations were observed after one day of storage under both conditions, although the immunoreactivity with CD4 was poor in the majority of cases stored at 4 degrees C and in two cases stored at room temperature. After three days of storage at 4 degrees C and after four days of storage at room temperature, a marked decrease in lymphocytes attached to the slides was observed. Immunoreactivity with CD8, CD20, CD45 and HLA-1 was well preserved, also, after one week of storage. Reactivity with CD3 was weak or poor after three days of storage in some cases. It is important to recognize that the preservation of the immunoreactivity of lymphocytes is dependent not only on the nutritive quality of pleural fluids but also on the cell preparation method.