Some murine thymic lymphocytes can form gap junctions.

Analysis of thymic lymphocytes isolated from weanling mice has revealed a minority population able to form permeable, intercellular (gap) junctions. This population is largest in mice aged between 3 and 6 weeks, much smaller in fetal and new-born mice and undetectable in mice aged 12 weeks or more. Fractionation of the thymocytes on Percoll gradients or with peanut agglutinin (PNA) shows the cells able to form junctions are enriched in lower density fractions and agglutinated by PNA, suggesting they are among the most immature. Fractionation by complement mediated cytotoxicity (CMC) and by fluorescence activated cell sorting (FACS) using monoclonal antibodies to specific cell surface determinants shows the junction forming cells are Lyt-1+/Lyt-2- and that the phenotype is associated with both high and low Thy-1 and H-2K epitope densities.