Increased reactivity of responding cells in the mixed lymphocyte reaction by a thymic humoral factor

Abstract

A thymic humoral factor (THF) induces competence in a certain sector of the lymphoid cell population. The target cell for THF activity was studied using the one-way mixed lymphocyte culture (MLC). Cells from various lymphoid tissues (responding cells) were preincubated in THF for 1 hour and then mixed with mitomycin-C-treated cells (stimulating cells). The results obtained indicate that THF increases MLC competence of lymphocytes from spleen and thymus origin of intact mice and that of spleen of thymus-deprived mice. In contrast, no enhancing effect in the MLC response by THF could be observed when bone marrow-derived spleen cells, cortisone-resistant thymocytes or lymph node cells were used as responding cells. These results confirm our hypothesis that THF leads to differentiation of young thymus-derived (T) cells, promoting them to maturation and thus to the acquisition of full immune competence.

Effect of human thymic epithelial conditioned medium on in vitro and in vivo alloantigen-induced lymphocyte activation in the mouse

“…The data on the biological activity of HTECM obtained in our study can be compared with those of other humoral factors from the thymus, like thymosin (13,15) and thymic humoral factor (THF) (16,17). HTECM increases the responder capacity of mouse thymocytes in one-way MLC.…”

“…This distinguishes HTECM from thymosin fraction 5, which is active only in cultures without ME and with a low baseline stimulation index (13). THF has been shown to increase MLC reactivity of thymocytes only after preincubation, while the continuous presence of THF in the cultures suppressed MLC reactivity (16,17). The addition of HTECM does not influence MLC reactivity of splenic lymphocytes at ah, a Thymocytes were incubated during 2 hr at 37°C with or without conditioned medium at a dilution of 1:15.…”

Partial restoration by in vivo thymosin of E-rosettes and delayed-type hypersensitivity reactions in immunodeficient cancer patients

“…Eventually, cancer patients may be preselected to receive thymosin based on in vitro changes in E-rosette numbers (Aiuti et al, 1975;Hong and Horowitz, 1975; and in mixed lymphocyte reaction (MLR) after thymosin preincubation (Umiel and Trainin, 1975). Patients may also be chosen for thymosin therapy because of data accumulating from studies in certain autoimmune diseases.…”

Amplification of the proliferative response to alloantigen by a factor present in an extract of syngeneic thymic lymphoid cells.

“…Preincubation of responding thymus or spleen cells with thymus humoral factor for 1 hr was reported to increase their "MLC competence." If thymus humoral factor was not washed from the responding cells but was allowed to remain in the culture medium throughout the 4-day period of assay, however, a substantial decrease in the MLC response was observed (44,45). Evidence has been presented that the prime target cells for thymus humoral factor are "young" thymus-derived lymphocytes (46) and that the effects of thymus humoral factor on these cells may be explained by rapid alterations in the cellular concentration of cyclic AMP (47).…”