Cells In Allogeneic Mixed Lymphocyte Reaction Research Articles

Defective self-recognition in subjects of far-advanced age.

The immunocompetence of 22 subjects aged 85-104 years (mean 90 +/- 1 years) was studied and compared to 21 young subjects aged 19-37 years (mean 30 +/- 1 years). The absolute lymphocyte number and the percentage of T and B lymphocytes in the peripheral blood was similar in the two groups. A marked decrease in phytohemagglutinin response of T-enriched lymphocytes from old subjects was observed. Autologous mixed lymphocyte reaction (MLR) was also profoundly reduced in old subjects. No difference between male and female subjects was observed. The responsiveness of enriched T lymphocytes to allogeneic irradiated non-T cells was only slightly impaired in the old individuals. Non-T cells from old and young subjects functioned equally well as stimulatory cells in allogeneic MLR. The data suggest that an alteration of T lymphocytes with regulatory function and of self-recognition is present in aged humans.

Subpopulation of T cells sensitive to natural thymocytotoxic autoantibody (NTA) of New Zealand mice. I. Distinct cytotoxic sensitivity of functional T cell subsets to NTA and anti-thy-1 antibodies.

NZB mice produce a natural thymocytotoxic autoantibody (NTA) capable of specifically injuring thymocytes and T cells. NTA-reactive antigen (NTA-A) shows a different density distribution among T cells, and partial killing with NTA and complement can eliminate T cells bearing NTA-A in high density. Thy-1 antigen is similar to NTA-A in this respect. To determine the effects of NTA and anti-Thy-1 on distinct functional subsets of T cells, Con A-induced suppressor T cell (Con A-Ts) activity against the allogeneic mixed lymphocyte reaction (MLR), responding T cell (TMLR) activity in the allogeneic MLR, and Con A-induced cytotoxic T cell (Con A-Tc) activity were examined simultaneously in BALB/c spleen cells before and after partial elimination of NTA- and anti-Thy-1-sensitive T cells. Treatment with NTA and complement resulted in a marked reduction in Con A-Ts activity, a significant increase in TMLR-activity and a slight and inconstant decrease in Con A-Tc activity. Since Con A-generated T's were much less sensitive to NTA, the NTA-sensitive T cells involved in Con A-Ts activity appear to be precursors or promoters of the Con A-Ts. In contrast, the precursors of Con A-Tc seem to relatively resistant to NTA. The increase in TMLR activity caused by NTA suggests the possibility that NTA is less cytotoxic for TMLR and cytotoxic for some suppressor T cells in allogeneic MLR. The monoclonal anti-Thy-1 antibody showed no such preferential cytotoxic effects on the three T cell functions. The NTA-sensitive T cells, in contrast to anti-Thy-1-sensitive T cells, were reduced gradually during Con A stimulation. All these findings indicate that NTA-A not only differs from Thy-1 antigen but that it appears to be a unique T cell antigen.

Autologous rosette-forming T cells as the responding cells in human autologous mixed-lymphocyte reaction.

Autologous rosette-forming cells (Tar cells) have surface and functional characteristics of post-thymic precursors and among these characteristics there are some that have been identified in the responsive cell of the autologous mixed-lymphocyte reaction (AMLR). We therefore did AMLR with circulating mononuclear cells from normal subjects using as responding cells either total T cells, T cells depleted of Tar cells, or purified Tar cells. The response of Tar cells in AMLR was significantly greater than that of total T cells and these responded significantly more than Tar-depleted T cells. Conversely, Tar cells responded less than total T cells or T cells depleted of Tar cells in allogeneic mixed-lymphocyte reactions. Increasing numbers of Tar cells gave significantly greater AMLR responses both alone and when added to diminishing proportions of Tar-depleted T cells to keep the number of T cells constant in the system. Tar cells are the responding cells in AMLR but not in allogeneic mixed-lymphocyte reactions.