Successive changes of the cellular composition in lymphoid organs of MRL-Mp/lpr-lpr mice during the development of lymphoproliferative disease as investigated in cryosections.

To analyze the tissue distribution of lymphocyte subsets of autoimmune MRL/Mp-lpr/lpr mice, we have studied cryostat sections of the lymphoid organs at different stages of the disease using monoclonal antibodies directed against Ly 1 (MAb 53-7.3), Ly 2 (MAb 53-6.7), B 220 (MAb 14.8), and mu heavy chain (MAb b.7.6). We have observed an increase of a characteristic subpopulation of lymphocytes (Ly 1+ (dull), Ly 2-, B 220+, sIgM-), first seen at age of 8 weeks. In lymph nodes, these cells are first organized follicle-like with sIgM+ cells in the center. Later (20th-29th weeks), mu+ cells are found almost exclusively in small areas between the follicles. In the spleen, the cells first appear in the outer periarteriolar lymphatic sheath. Later, they are distributed within the follicles. sIgM+ cells disappear from the follicles; few remain within the marginal zone. In the thymus, some mice show a highly increased number of mu+ cells in the medulla. In Peyer's Patches, these Ly 1+ (dull) B 220+ cells are found predominantly in the interfollicular zone.