Reactivity Of Lymph Node Cells Research Articles

Enhanced Cellular Immune Response and Reduced CD8+ Lymphocyte Apoptosis in Acutely SIV-Infected Rhesus Macaques after Short-Term Antiretroviral Treatment

Losing the decisive virus-specific functions of both CD4+ and CD8+ T lymphocytes in the first weeks after immunodeficiency virus infection ultimately leads to AIDS. The SIV/rhesus monkey model for AIDS was used to demonstrate that a 4-week chemotherapeutic reduction of viral load during acute SIV infection of macaques allowed the development of a competent immune response able to control virus replication after discontinuation of treatment in two of five monkeys. Increasing SIV-specific CD4+ T-helper-cell proliferation was found in all macaques several weeks after treatment, independent of their viral load. However, only macaques with low viral loads showed persistent T-cell reactivity of lymph node cells. In contrast to animals with higher viral loads, T-helper-cell counts and memory T-helper cells did not decline in the two macaques controlling viral replication. Lymphocyte apoptosis was consistently low in all treated macaques. In contrast, high CD8+ lymphocyte death but only slightly increased CD4+ lymphocyte apoptosis were observed during the first weeks after infection in untreated control animals, indicating that early apoptotic death of virus-specific CTL could be an important factor for disease development. Antiretroviral treatment early after infection obviously retained virus-specific and competent T lymphocytes, whereby a virus-specific immune response could develop in two animals able to control the viral replication after cessation of treatment.

Immunoregulation in experimental filariasis. I. In vitro suppression of mitogen-induced blastogenesis by adherent cells from Jirds chronically infected with Brugia pahangi.

Nonspecific immunoregulatory events were examined in inbred jirds chronically infected with Brugia pahangi. The responsiveness of spleen cells from infected animals to the T cell mitogens PHA and Con A and to the B cell mitogens, LPS and PWM, was found to be suppressed by as much as 90% when compared with the reactivity of lymphocytes from normal animals. Furthermore, spleen cells from infected jirds were capable of suppressing the mitogen reactivity of normal spleen cells. Depletion of cells adherent to nylon wool, glass wool, or plastic alleviated the regulatory activity exerted by spleen cells from infected jirds. Addition of indomethacin, an inhibitor of prostaglandin synthetase, to cultures of spleen cells from infected animals did not alter the suppression observed. In contrast, lymphocytes from the peripheral lymph nodes of infected jirds did not exhibit depressed T cell mitogen reactivity and were incapable of suppressing the PHA or Con A responsiveness of normal lymph node cells. However, the reactivity of lymph node cells from infected jirds to B cell mitogens, LPS and PWM, was suppressed. These results imply the existence of multiple regulatory mechanisms, at least one of which is restricted to the spleen. The relevance of nonspecific regulation to development of parasite-specific immunologic reactivity and to the infection is discussed.

Effects of antithymocyte serum on lymph node cells participating in the graft-vs-host reaction

BALB/c mice were injected with 0.1 ml of antithymocyte serum (ATS) and tested at various times thereafter for graft-versus-host (GVH) reactivity of lymph node cells (LNC) and spleen cells (SC). Splenomegaly produced by LNC or SC injected alone was used as a measure of precursor T cell function and the capacity of such cells to produce synergy when combined with normal thymocytes was used to evaluate amplifier T cell activity. In lymph node, both precursor and amplifier function were strikingly depressed 2 days after ATS administration; by day 11, precursor function showed slight recovery while amplifier activity had recovered to supranormal levels. In spleen, precursor activity recovered two fold between 2 and 11 days after ATS inoculation but no amplifier activity could be detected at day 11. Since donors had not been deliberately stimulated with alloantigens prior to testing of LN and SC GVH acivity, these studies demonstrate (a) that precursors and amplifiers are disinct T cell populations that are committed to express unique functional activities before antigen exposure and (b) that, following depletion with ATS, these two populations recover independently at different rates in separate lymphoid compartments.

Subpopulations of multiparous rat lymph‐node cells cytotoxic for rat tumour cells and capable of suppressing cytotoxicity in vitro

Lymph-node cells (LNC) from multiparous pregnant rats were separated on columns prepared from nylon wool, and tested for cytotoxicity against target tumour cells. Reactivity of LNC towards hepatoma D23 and mammary carcinoma AAF57 was demonstrated in cell populations retained on the nylon wool, and not with cells eluted from the column. Although only 25% of the samples of unfractionated LNC were cytotoxic for tumour cells, retained cell fractions were cytotoxic in 11 out of 12 tests (p = less than 0.05). Similarly retained LNC were also cytotoxic for 15-day-old embryo cells but not for normal adult rat fibroblasts. Using multiparous rat serum it was shown that the reactivity of the retained LNC population could be abrogated in eight out of 11 tests (p = less than 0.05). The LNC population recovered from the nylon wool constituted 28 to 35% of the original LNC preparation, and consisted of 60-70% Ig-bearing cells together with a subpopulation of cells responding to soluble PHA. Separation of multiparous LNC on glass beads coated with rat Ig and then rabbit anti-rat Ig (in excess) also demonstrated the retained cell population to be cytotoxic against tumour cells. Approximately 17-20% of the original cell population was recovered from cells retained on the column, and consisted of an enriched Ig-bearing cell population (65-80% Ig-bearing cells) and LNC responsive to PHA. Carbonyl iron treatment of multiparous rat LNC was found to remove detectable cytotoxicity from multiparous rat LNC preparations. The cytotoxicity of multiparous rat LNC retained on nylon wool was also abolished following incubation with carbonyl iron. Definite conclusions as to the nature of the effector cell cannot be drawn from this test, since carbonyl iron treatment was found to remove not only phagocytic cells from LNC preparations but also a proportion of other cell populations including Ig-bearing lymphocytes... In addition to detecting a cytotoxic LNC population reactive towards tumour-associated embryonic antigens (retained fractions from nylon-wool column separation), a subpopulation of multiparous rat LNC was demonstrated in cell fractions eluted from the nylon wool which was shown to suppress the cytotoxicity of the retained multiparous LNC population. The exact nature of this subpopulation of LNC and the mechanism of action is at present not known.

Cytotoxic activity of lymph node cells from mice treated with immunosuppressive antilymphocyte serum.

A horse antimouse lymphocyte serum was shown to be immunosuppressive in prolonging the survival of C3H skin allografts on Balb/c mice. Despite the immunosuppressive effect of that preparation, however, mixtures of histoincompatible lymph node cells obtained from treated mice showed: (a) an increased local reactivity in the skin of the X-irradiated hamster; (b) a more rapid clearance from those intradermal injection sites; and (c) a significant, in vitro production of nonspecific lymphocytotoxic substance (s). We conclude that the liberation of cytotoxic substance (s) through mouse cell lysis is responsible, in part, for the increased local reactivity of lymph node cells obtained from immunosuppressed mice.

Systemic and Local Immunological Activity of Lymph Node Cells from Mice Treated with Antilymphocyte Serum

SummaryAn immunosuppressive antilymphocyte serum prolonged the survival of skin allografts and suppressed the systemic graft-versus-host reactivity of lymph node cells from treated mice. Those same lymph node cells, however, were highly reactive when tested in the skin of the X-irradiated hamster, and that reactivity was dependent, at least in part, upon the presence of viable, histoin-compatible cell populations. We conclude that cells from the ALS-treated mice react well in that local assay while showing suppressed reactivity in the systemic assays of immunocompetence.