Lymphoid cells, evidence

Postmortem examinations of persons who died as a result of exposure to H have shown depletion of lymphoid cells in the spleen, thymus, and other lymphatic organs depletion of hematopoietic cells of the bone marrow necrosis and desquamation of epithelium in the small intestine acute ulceration of the duodenum membranous laryn-gotracheobronchitls and pulmonary edema, congestion, and patchy emphysema that may be complicated by bronchopneumonia or other evidence of pulmonary infection.2>47... 

Pemis, B., Brouet, J.C., Seligmann, M. (1974). IgD and IgM on the membrane of lymphoid cells in macroglobulinemia. Evidence for identity of membrane IgD and IgM antibody activity in a case with anti-IgG receptors. Eur. J. Immunol. 4,776-778. 

Stein, H., Mason, D. Y., Gerdes, J., O Connor, N., Wainscoat, J., Pallesen, G., Gatter, K., Falini, B., Delsol, G., Lemke, H., etal. The expression of the Hodgkin s disease associated antigen Ki-1 in reactive and neoplastic lymphoid tissue Evidence that Reed-Sternberg cells and histiocytic malignancies are derived from activated lymphoid cells. Blood 66, 848—858 (1985). 

Wang SC, Kanner SB, Ledbetter JA, Gupta S, Kumar G, Nel AE (1995) Evidence for LFA-l/ICAM-1 dependent stimulation of protein tyrosine phosphorylation in human B lymphoid cell lines during homotypic adhesion. J Leukoc Biol 57 343-351... 

Thus, the bulk of evidence available to date would suggest at least in mice that the spleen contains a population of thymic hormone-responsive lymphoid cells that functions mainly in the suppression of immune responses, perhaps masking concomitant helper effects. In the thymus, the predominant effects of thymic peptides appear to be the induction of functional helper cells, possibly by the enhancement of lymphokine production. The effects of thymulin, thymosin, or other thymic factors on IL-2 production may indeed represent a major function of the endocrine thymus, since IL-2 has been shown to be a potent physiological promoter of T cell maturation (Ruscetti and Gallo, 1981). 

A role in immunomodulation was first suggested because lymphoid cells can accumulate ascorbate to concentrations at least 50 times higher than that present in blood plasma. There is much evidence in the literature that supports stimulation by ascorbate of both humoral and cell-mediated immune responses. Below we review the available data supporting an immunomodulatory role for the vitamin. 

Eichler and Kruger [147] showed by tissue culture experiments, that various viral antigens related to virus replication and to the synthesis of structural components appear earlier in cells stimulated with . purpurea expressed sap, timunox and TP-1, but not following the stimulation with isoprinosine. Similarly, virus genome containing cells increased after stimulation with thymic preparations (thymostimulin and thymopentin), but not with . purpurea expressed sap and isoprinosine. The authors conclude that the synthesis of proteins or DNA of lym-photropic viruses may be transiently enhanced when lymphoid cells are stimulated by certain non-specific immunostimulants. There was no evidence, however, of increased virus replication. 

The available evidence indicates that immunoglobulin biosynthesis takes place largely on polyribosomes bound to membrane surfaces in the rough endoplasmic reticulum of lymphoid cells (145-147) the polyribosomes are present in the microsomal fraction isolated from a cell homogenate. The possibility that some biosynthesis may occur on free polyribosomes has not been rigorously excluded. After release from the polyribosome an immunoglobulin molecule traverses the membrane into the cisternal compartment where it travels to the smooth endoplasmic reticulum (devoid of polyribosomes) and to the Golgi vesicles, prior to its release from the cell. 

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