A DISTINCT DISTRIBUTION OF NATURAL-KILLER-CELL SUBGROUPS IN HUMAN TISSUES AND BLOOD

Natural killer (NK) cells have been subdivided according to their CD16 /CD56 expression into at least 2 subgroups. We examined the distributi on of these NK subgroups in humans. In the blood of normal individuals , CD16(++)/CD56(+)/CD3(-) NK cells predominate, constituting more than 90% of all NK cells. In contrast, decidua is infiltrated almost exclu sively by CD 16(+/-)/CD56(+)/CD3(-) NK cells (>90%), a fact so far see n in context with decidua being an immunoprivileged tissue. However, t his NK subgroup can also be detected in the blood, where it comprises about 10% of NK cells. We have found that normal (colon) as well as ne oplastic (ovarian and urothelial carcinoma) tissues are also predomina ntly infiltrated by this CD16(+/-) NK subgroup. Lymphatic fluid draini ng solid tissues contains CD16(+/-) NK cells exclusively, with absolut e numbers of NK cells being very low. No predominating NK subgroup was seen in ascites. CD16(+/-) NK cells, when tested against the target c ell lines K562 and JAR, revealed a cytotoxic spectrum different from C D16(++) NK cells and from T cells. A change in the CD16/CD56/CD3 pheno type was not seen in either subgroup in long-term cultures containing IL-2 (1,000 U/ml). Our data indicate that the decidua is not the only solid tissue infiltrated by CD 16(+/-) NK cells. Other normal and mali gnant tissues were also infiltrated predominantly by this NK cell subg roup. We suggest that CD16(+/-) NK cells represent a functionally dist inct NK subgroup involved in the surveillance of solid tissues. (C) 19 98 Wiley-Liss, Inc.