Lymphokine activated killer (LAK) activity in normal pregnancy

Abstract

With a view to define inherent tendency in activity of lymphokine activated killer (LAK) cell during pregnancy a series of test has been conducted with consequently evolved results quoted in the following summary;1) In an extensive program of test there was a marked fall in activity of LAK significantly over the period from initial-to third trimester (p<0.01). It, however, rapidly recovered at the occasion of delivery until consequent difference has become no longer distinctive when compared to the equivalent of non-pregnant subject.2) Another research directed to a possible influence of adherent cells and pregnant serum on the LAK activity which might possibly account for the loss of LAK activity, gave a conclusive evidence to support that both factors would give none of influence on the LAK activity.3) Further study through flow cytometry on the behavior of lymphocyte subsets (OKT3, OKT4, OKT8, Leu7, Leull, OKIal and OKM1) under cultivation made with added interleukin 2 (IL-2) did show none of difference between pregnant-and non-pregnant subjects. From this fact it may be retrospectively inferred that loss of LAK activity during pregnancy would be attributed to dysfunction rather than to reduced number of LAK cells.4) A factor to suppress IL-2 production capability of peripheral blood lymphocytes under PHA stimulation was identified in the serum of pregnant subjects, whereas it was not the case with the subjects during puerperal phase. With the above decisive fact it has been shown convincingly that induction of LAK activity during pregnancy would have been suppressed by etiological mechanism involving both loss of IL-2 production and dysfunction of LAK cells, viz. an immunological environment helpful to maintain pregnancy may have been thereby provided for.