8-Methoxypsoralen plus UVA treatment increases the proportion of CLA+ CD25+ CD4+ T cells in lymph nodes of K5.hTGFß1 transgenic mice.

8-Methoxypsoralen plus UVA (PUVA) photochemotherapy is an effective treatment for many skin diseases including psoriasis. However, its exact mechanism of therapeutic action is incompletely understood. Previously, in K5.hTGFß1 transgenic psoriatic mice, we found that PUVA induces Foxp3+ CD25+ CD4+ regulatory T cells in both lymph node and spleen. Now, in the same model, we investigated whether cutaneous lymphocyte-associated antigen (CLA) mediates PUVA's effect on homing of CD25+ CD4+ T cells to the lymph nodes of K5.hTGFß1 transgenic mice. We found that a low dose of topical PUVA maximally increased the proportion of CLA + CD25+ CD4 + T cells in the lymph nodes by up to 8-fold. We also observed an increased number of Foxp3+ CD25+ T cells in the skin of the mice after PUVA treatment. Together, these findings suggest that PUVA affects the homing of regulatory T cells.

Effects of low-doses of X-rays on the expression of human cell surface CD2 antigen in CD2+ CHO cells.

Thioguanine resistant CHO cells (HPRT-) were stably cotransfected with pSV2-gpt and pi H3-CD2 vectors using the calcium phosphate coprecipitation technique. The effects of single low doses of ionizing radiation were studied in a CD2+ CHO clone. The CD2+ phenotype responsible for binding sheep erythrocytes and rosette formation, was not affected by X-rays doses in the range 2-6 cGy. However, after 10 cGy of X-irradiation, 50% of the cells lost the CD2+ phenotype. These results suggest that this CD2+ clone might be a very sensitive indicator of very low X-ray doses. The implications of the phenotypic changes, observed after very low doses of irradiation, are discussed.

T-cell regulation of CD5+ B-cell activity in normal mice.

The differentiation of plaque-forming cell (PFC) precursors against bromelain-treated syngeneic erythrocytes (Br MRBC) into PFC induced in vitro by LPS is down-regulated by nylon non-adherent (nylon-passed--NP) T cells and by nylon adherent (NA) T cells. NA T cells are more potent inhibitors than NP T cells. This regulatory activity of NA and NP T cells results from an interaction between CD4+ radioresistant and CD8+ radiosensitive T cells. Furthermore CD4+ T cells from the NA fraction but not from the NP fraction are activated cells: their inhibitory activity is abrogated after preincubation with cycloheximide. These results are discussed within the overall framework of T-cell regulation of autoimmune anti-Br MRBC B-cell subsets.

Changes of CD2 receptor density determined by electron microscopy on blood lymphocytes following radiation treatment for breast cancer.

Changes of relative CD2 receptor on lymphocytes were examined in 11 women following radiation treatment for breast cancer by electron microscopy using antibody-coated gold particles. Proportions of blood lymphocytes with a high density of CD2 receptors were reduced, whereas those with no or a low density of such receptors were increased after radiation treatment.

The expression and sequences of T cell antigen receptor beta-chain genes in the thymus at an early stage after sublethal irradiation.

The sequential appearance of the thymocyte subpopulations and TCR gene messages occurred in the thymus of AKR mice (H-2k, Mlsa) from 7 to 14 days after sublethal irradiation. The thymocytes on day 7 after irradiation were composed of a large number of CD4+CD8+ blast-like cells and a relatively high proportion of CD4-CD8- cells (15 to 25%) but few CD3highCD4+CD8-/CD4-CD8+ cells. Approximately 22% of the CD4-CD8- cells were CD3high and -27% of the CD3highCD4-CD8- cells (-6% of whole CD4-CD8- cells) were F23.1+. The thymocytes on day 7 expressed a large amount of gamma- and delta-chain gene transcripts but reduced levels of alpha- and beta-chain gene transcripts. The V gene repertoire of 18 functional beta-chain cDNA derived from the thymocytes on day 7 was compared with those of 20 functional beta-chain cDNA derived from the thymocytes on day 14 which were composed of a large number of CD3lowCD4+CD8+ small-sized cells and a small number of CD3highCD4+CD8- cells. It is noteworthy that the distribution of V beta genes expressed in the thymocytes on day 7 was much the same as that in the thymocytes on day 14 but significantly different from that in normal BALB/c thymocytes as previously described. Interestingly, neither V beta 8.1 nor V beta 6 genes, which are important for recognition of the product of the Mlsa locus, was detected in these two cDNA libraries. These results suggest that clonal selection of TCR V beta repertoire, irrespective of positive or negative selection, appears to occur at the early stage of T cell differentiation, i.e., on the blast-like CD4+CD8+ thymocytes.

[Changes in the antigenic phenotype of mouse thymocytes after exposure to chemical inducers of differentiation and ionizing radiation]. / Izmenenie antigennogo fenotipa timotsitov myshei pri deistvii khimicheskikh induktorov differentsirovki i ioniziruiushchei radiatsii.

Irradiation of a mouse thymocyte fraction enriched by T-lymphocyte precursors changes the antigenic phenotype of cells toward the increase of their highly differentiated forms. Similar changes in membrane marker antigens are produced by chemical inductors of differentiation and thymotropin. The changes in the cell phenotype induced by the above agents are associated with both membrane and intragenome rearrangements. The results of the experiments on preventing the expression of some antigens by puromycin and the data on the level of spontaneous genome lesions in thymocyte fractions have prompted an assumption that destabilization of the genome upon irradiation increases DNA injury above some critical level which may serve a stimulus for "sorting out" the most radiosensitive thymocyte fraction.