Effect of cryopreservation on human lymphocyte surface markers determined by monoclonal antibodies

The effect of cryopreservation in liquid nitrogen on the relative proportions of lymphocyte subsets defined by a panel of OKT monoclonal antibodies was investigated in 15 healthy subjects. DMSO (dimethylsulfoxide) was used as a cryopreservative agent and lymphocytes were frozen in a programmed control device. After a period up to 4 months the cells were thawed and the relative proportion of positive lymphocytes was determined by immunofluorescence and compared with the results obtained on fresh samples. No substantial changes were observed in the percentage of cells expressing OKT3, OKT4, OKT6, OKT8, OKIa, OKM and D 1/12 monoclonal antibodies. On the contrary, the number of cells positive for 5/9 and MLR 4 monoclonal antibodies, which are directed against alloactivated T cells, was decreased after freezing. We conclude that cryopreservation does not affect the relative proportion of cells expressing markers defined by the most common monoclonal antibodies and can be useful for serial immunological studies.