MAC technique (morphology antibody chromosomes) in phenotypic identification of proliferating NK and T cells in interleukin-2-stimulated lymphocyte cultures.

Human peripheral blood lymphocytes were activated with recombinant interleukin 2 (rIL-2) and cultured in fetal calf serum (FCS)- or human-AB-serum-supplemented media. Proliferative cells were identified by the MAC technique (morphology antibody chromosomes) which enables the immunoenzymatic identification of both mitotic and non-proliferating cells in unfractionated lymphocyte populations. The results indicate that the phenotype of more than 90% of proliferative lymphocytes can be characterized by using antibodies against T cells and NK cells. Substantial mitotic activity of CD4-positive (CD4+) T cells was observed only in FCS-supplemented cultures, whereas in serum-free or human-AB-serum-supplemented cultures mostly CD8+ T cells and NK cells proliferated. The proportion of NK cells among all mitotic cells varied between 14 and 32%. Interestingly, in unfractionated cultures approximately 13% NK cells entered mitoses in the presence of rIL-2, suggesting that the poor proliferative capacity of purified NK cells demonstrated previously may be due to the lack of accessory stimulatory signals. The proliferation of B cells was minimal in all experiments. The MAC technique is a useful addition to the techniques by which lymphocyte growth regulation is monitored.