Mixed lymphocyte reactivity of human lymphocytes primed in vitro. I. Secondary response to allogenic lymphocytes

Abstract

In order to study the mixed lymphocyte culture reactivity of human lymphocytes primed in vitro, a nucleopore culture chamber technique allowing human lymphocytes to be cultured for a period of at least two weeks has been developed. During the primary culture period in nucleopore chambers, human lymphocytes were sensitized against mitomycin-treated allogenic stimulating cells. It was shown that the stimulated lymphocytes underwent a blastogenic reaction and the results suggest a reversion to the state of small, resting, primed lymphocytes. In vitro primed lymphocytes displayed allogenic memory. This was characteristic of a secondary response, which is shown by the following: 1) acceleration, the peak of thymidine incorporation occurring on day 4,2) specificity, the accelerated response was observed only when the primed lymphocytes were confronted with the cell used for priming. Contact with a third party cell did not produce this kind of activation. 3) Amplitude; the peak DNA synthesis response was greater than that of unprimed lymphocytes cultivated for the same length of time.