INFLUENCE OF INTERLEUKIN-2 AND INTERFERON-α ON LYMPHOCYTE AGGREGATION AND LYMPHOCYTE-PLATELET CLUSTER FORMATION

Abstract

The aim of the research was to study the direct and platelet-mediated intercellular adhesion of blood-derived lymphocytes, as well as the influence of interleukin-2 and interferon-α on it.Materials and methods. Whole blood samples from 34 apparently healthy individuals were collected using vacuum tubes containing sodium citrate (3,8%). A suspension of lymphocytes and platelets was isolated on a Ficoll-Urografin gradient. Light microscopy was used to determine the percentage of lymphocyte-platelet aggregates. The effect of cytokines was studied by adding human recombinant interleukin-2 and interferon-α to whole blood, and incubating for 4 hours in a thermostat at 37 °C. After incubation the necessary parameters were counted using the method described above. The results were expressed as mean values and standard deviations (± SD). Statistical processing of the data was performed using the Mann-Whitney U-test and the Kolmogorov criterion (Statistica 10), with differences considered significant at p < 0.05.Results. The study showed that in addition to lymphocyte-platelet aggregates (11 ± 3.6%), the total pool of lymphocytes also contained intercellular aggregates of lymphocytes (3 ± 3,8 per 100 cells) and lymphocyteplatelet clusters (2 ± 0,6 per 100 cells). It was found that the addition of interleukin-2 (IL-2) led to an increase in lymphocyte-platelet aggregates (LPA) and lymphocyte-platelet clusters by 1,8 times (p < 0,001) and 3,3 times (p < 0,001), respectively, compared to the control group. In contrast, incubation of blood samples with interferon-α (IFN-α) led to a decrease in the number of LPA (by 5.5 times compared to the control, p < 0,001) and almost prevented the ability of lymphocytes and platelets to form clusters. The presence of the abovementioned cytokines in the incubated blood did not affect the ability of lymphocytes to form aggregates with each other.Сonclusion. It was found that IL-2 increases the ability of lymphocytes and platelets to form clusters, while IFN-α significantly reduces this ability and has an inhibitory effect on the ability of these cells to form LPA. In our opinion, it is important that the effects of these cytokines were manifested only upon contact of lymphocytes with platelets.