Lymphocyte dysfunction in cartilage hair hypoplasia. II. Evidence for a cell cycle specific defect in T cell growth

Abstract

Defects of in vitro B and T lymphocyte function and impaired delayed type hypersen-sitivity reactions, as well as an increased risk of lethal viral infections have been reported in cartilage hair hypoplasia (CHH), an autosomal recessive form of short limbed dwarfism. We have previously found an intrinsic proliferative defect that affected several cell types from CHH individuals. In order to further evaluate it we developed continuous T cell lines (CTCL) from CHH and normal individuals. The T cells from cultures of CHH and normal individuals were indistinguishable with respect to cell surface antigens characteristic of fully differentiated T cells, as defined by monoclonal antibody analysis. However, CHH T cells produced significantly less interleukin 2 (IL2) than normal T cells and the growth of CHH CTCL in response to exogenously supplied IL2 was markedly diminished (cell cycle 120-165 hr) compared to normal CTCL (cell cycle 48-60 hr). Furthermore, the exogenous IL2 was not absorbed from growth medium by CHH CTCL at the same rate as normal CTCL. Both production and utilization of IL2 are cell cycle specific events that occur during G₁ phase before the onset of DNA synthesis (S phase). Thus, CHH T lymphocytes appear to have a defect related to G₁ phase that results in a longer cell cycle for individual cells, and leads to decreased proliferation of the population. We postulate that this G₁ phase defect is present in multiple cell types in CHH and that analysis of continuous T cell lines from CHH individuals may permit the identification of this defect.