Nude Marrow Research Articles

Anti-brain antisera bind primarily to non-T cells in mouse bone marrow.

Anti-brain heteroantisera are widely employed for the delineation of T lymphocytes in lymphomyeloid organs despite compelling evidence demonstrating the cross reactivity of such reagents with unrelated hemopoietic cells. The experiments described in the paper utilized absorptions of a fluoresceinated goat anti-rat brain antiserum with thymocytes or nude bone marrow cells to determine the validity of using such an antiserum to identify T cells in the thymus, lymph nodes, spleen, and bone marrow of CBA/J mice. Thymocyte absorption of this fluoresceinated antiserum removed virtually all of the staining of thymus, lymph node, and spleen cells by this reagent. In contrast, the percentage of labeled marrow cells was unchanged by thymocyte absorption of the anti-rat brain antiserum, although the staining could be eliminated by absorption with nude bone marrow. These results suggest that anti-brain antisera can be employed as dependable T-cell probes with suspensions of the thymus or peripheral lymphoid organs. However, the vast majority of marrow cells staining with the anti-brain antisera are not T cells. Therefore, anti-brain antisera should not be utilized to discern T lymphocytes in this tissue unless additional absorptions (with nude marrow) or special controls are performed.

T-Lymphocyte precursors. I. Synergy between precursor and mature T lymphocytes in the response to concanavalin A.

When mouse bone marrow cells are mixed with cortisol-resistant thymocytes and stimulated in vitro with concanavalin A, the mitogenic response observed is much greater than additive, that is, it is synergistic. Between 94 and 96% of responding cells could be identified as T cells (Thy-1 positive) and of these, 79-100% derived from the cortisol-resistant thymocyte population, not from the bone marrow. Purified macrophages could not replace bone marrow; and marrow depleted of mature T or B cells worked as well as normal marrow. Thus, T and B cells and macrophages were ruled out as the synergizing cell of bone marrow. Nude spleen contained 10 times as many precursors of T cells as did nude marrow and was 10 times better at synergy with cortisol-resistant thymocytes. This implication of the pre-T cell as synergizer was supported by the finding that the synergistic activity of marrow was lost on preincubation, but maintained if the preincubation medium contained thymosin or cyclic AMP. Thus, the ability to enhance the response of relatively mature T cells to Con A is a property of pre-T cells. It is anticipated that this property will allow more detailed studies of T-cell precursor development in mice, and possibly in man.