The T-cell receptor repertoire is strikingly similar in older nude mice compared to normal adult mice.

Due to the absence of a normal thymus, nude mice are characterized by low numbers of mature T cells. It has been shown in older nude mice that appreciable numbers of Thy-1+, CD8+ and, to a much lesser extent, CD4+ T cells can be found. A second T-cell receptor (TCR), gamma delta-TCR, has been shown to be expressed by a large number of T cells in young and old nude mice. Recent data suggest that certain gamma and delta chain variable (V), diversity (D), joining (J) and constant (C) region genes are associated with both temporal and spatial organization of the gamma delta-T-cell repertoire in normal mice. In this study we observed the predominant use of V gamma 2J gamma 1C gamma 1 and V delta 5J delta 1C delta in the spleen of older nude mice. In the skin, a near exclusive expression of V gamma 3J gamma 1C gamma 1 and V delta 1J delta 2C delta gene segments was observed. In addition, a dendritic epidermal cell (DEC) clone was isolated from the skin of a nude mouse and expressed a gamma delta receptor consisting of V gamma 3J gamma 1C gamma 1 and V delta 1J delta 2C delta. Preliminary results show that this clone kills only YAC (and NK target) and not other tumor targets. The killing can be redirected by anti-CD3 monoclonal antibody which suggests that the receptor is potentially functional. These results demonstrate that without normal thymus development nude mice not only produce gamma delta-T cells with a lytic potential, but also manage to express gamma delta-TCR's that are similar in spatial arrangement to normal mice. This suggests a possible difference in the requirements for gamma delta-TCR ontogeny.