Abundance of NKT cells in the salivary glands but absence thereof in the liver and thymus of aly/aly mice with Sjogren syndrome

It is known that ALY/Nsc Jcl-aly/aly (aly/aly) mice that congenitally lack lymph nodes fall victim to Sjogren syndrome as a function of age. We invest igated how TCRint cells of extrathymic origin and TCRhigh cells of thymic o rigin are distributed in various organs of these mice, Although the distrib ution of T-cell subsets was not different between control aly/+ and aly/aly mice in youth in any of the tested organs, the proportion of TCRint cells in the liver and spleen of aly/aly mice increased with aging. Usually, TCRi nt cells in the liver comprise a half-and-half mixture of a NK1.1(+) subset (i.e., NKT cells) and a NK1.1(-) subset. In constrast, almost all expandin g TCRint cells in various immune organs of aly/aly mice were found to be NK 1.1(-). A large proportion of lymphocytes, including NK cells and TCRint ce lls, were also present in the salivary glands of aly/aly mice. Interestingl y, these TCRint cells in the salivary glands contained an NK1.1+ subset (i. e., NKT cells) that used an invariant chain of V alpha 14J alpha 281 for TC R alpha beta (>50%). Moreover, gamma delta T cells that used V gamma 1, 2, 4/V delta 1, 4, 6 mRNAs, different from those of gamma delta T cells in the liver and intestine, were abundant. Possibly reflecting the in situ genera tion of these T cells in the salivary glands, the expression of RAG-2 mRNA was evident by the RT-RCR method. These results suggest that (i) inflammato ry lymphocytes that evoke Sjogren syndrome in aly/aly mice are NK cells or TCRint cells (both NK1.1(+) and NK1.1(-) subsets) and (ii) TCRint cells in the salivary glands might be generated in situ, (C) 1999 Academic Press.