Quantitative Estimation of the Reactivity of Normal and Hodgkin's Disease Lymphocytes with Thymidine-2-¹⁴C

Abstract

SINCE lymphoid blood cells play an important part in the mediation of delayed hypersensitivity and homograft rejection^1–4, it is reasonable to expect that further understanding of these forms of immunological responsiveness will come from appropriate in vitro investigations of circulating lymphocytes. Lymphocyte reactivity in vitro may also provide insight into the pathogenesis of diseases involving immune or autoimmune mechanisms and provide a measure of the efficacy of immunological suppression. It has been the particular goal of several laboratories^5–7 to apply such lymphocyte investigations to the problem of donor selection for human organ transplantation, and for this purpose several techniques for the culture of lymphocytes and the measurement of their reactivity have been developed. Inasmuch as the methods being used to determine human lymphocyte reactivity, that is, conversion of lymphocytes to large immature cells^5,6, counting of mitoses^5,6 and autoradiography with tritiated thymidine⁵ are laborious and subject to several sources of error, a simple quantitative technique for following lymphocyte reactions in vitro would be of considerable value. The present communication describes such a method which is based on the incorporation of ¹⁴C-labelled thymidine into the deoxyribonucleic acid (DNA) of reacting cultured lymphocytes. This method was developed to investigate the lymphocytes of patients with Hodgkin's disease, a condition in which delayed type (cell-mediated) hypersensitivity and homograft rejection are regularly depressed⁸.