Monocyte chemoattractant protein-1 and macrophage inflammatory protein-2 are involved in both excitotoxin-induced neurodegeneration and regeneration.

Intrahippocamal injections of kainic acid (KA) significantly increase the expression of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) in the ipsilateral hippocampus at 2-4 h and 21-45 days post-administration, suggesting the possible involvement of these chemokines in both neurodegenerative and regenerative processes. To examine the possible role of these chemokines on neuronal cell death, hippocampal neurons were incubated with either MCP-1 or MIP-2 in vitro and examined to assess the effects on neuronal cell viability. These treatments resulted in significant neuronal apoptosis that could be abrogated by prior treatment with the caspase-1 inhibitor, Z-VAD-FMK, the caspase-3 inhibitor, Z-DEVD-FMK, the Galphai inhibitor, pertussis toxin, or the MAO-B inhibitor, (-)deprenyl. Furthermore, this chemokine apoptotic effect could also be observed in vivo as intrahippocampal injections of MCP-1 or MIP-2 resulted in the apoptosis of hippocampal neurons, thus supporting a direct role of these chemokines in neuronal death. In contrast, immunohistological analysis of kainic acid lesions on days 21-45 revealed significant expression of MCP-1 and MIP-2 associated with reactive astrocytes and macrophages, respectively, with no apoptotic populations being observed. These results suggested that these chemokines might also mediate distinct biological effects on local microenvironmental cell populations at various stages post truama and during cellular repair. To address this possibility, astrocyte were cultured in the presence or absence of these chemokines and examined by microarray analysis for effects on astrocytes gene expression. A number of genes encoding proteins associated with inflammation, cellular signaling, differentiation, and repair were directly modulated by chemokine treatment. More specifically, the RNA and protein expression of the neurotrophic factor, basic fibroblast growth factor (bFGF), was found to be significantly increased upon culture with MCP-1 and MIP-2. Conditioned media derived from chemokine-stimulated astrocytes also facilitated bFGF-dependent neuronal cell differentiation and promoted survival of H19-7 neurons in vitro, suggesting a possible role for chemokine-activated astrocytes as a source of trophic support. Taken together, these data support possible autocrine and paracrine roles for MCP-1 and MIP-2 in both the "death and life" of hippocampal neurons following CNS injury.

Serum antibodies to HIV-1 are produced post-measles virus infection: evidence for cross-reactivity with HLA.

Convalescent sera obtained from patients who were recently recovered from an acute measles virus infection were tested for the presence of anti-HIV-1 antibodies by Western blot analysis. While 16% (17/104) of control sera displayed reactive bands to a variety of HIV proteins, 62% (45/73) of convalescent sera demonstrated immunoreactive bands corresponding to HIV-1 Pol and Gag, but not Env antigens. This cross-reactivity appears to be the result of an active measles infection. No HIV-1 immunoblot reactivity (0/10) was observed in sera obtained from young adults several weeks after a combined measles, mumps, and rubella (MMR) vaccination. Interestingly, examination of anti-HLA typing sera specific for either class I and class II molecules revealed that 46% (19/41) of these sera contained cross-reactive antibodies to HIV-1 proteins. Absorption of measles sera with mixed lymphocyte reaction (MLR)-activated lymphocytes and/or HIV-1 recombinant proteins significantly decreased or removed the presence of these HIV-1-immunoreactive antibodies. Together, these findings suggest that the immune response to a natural measles virus infection results in the production of antibodies to HIV-1 and possibly autoantigens.

Regulation of interleukin 2 and interleukin 2 receptor gene expression in human T cells: I. Effect of Ca2+-ionophore on phorbol myristate acetate co-stimulated cells.

Human peripheral blood T lymphocytes were treated with phorbol myristate acetate (PMA), an activator of protein kinase C (PKC) activity, and with the calcium ionophore A23187. The resulting accumulation of specific mRNA for interleukin 2 (IL-2) and interleukin 2 receptor (IL-2R), as well as IL-2 secretion and membrane IL-2R expression were examined. At low concentrations (0.1 microM), A23187 synergized maximally with PMA to induce proliferation, to increase IL-2R mRNA levels and the expression of membrane IL-2R, and to produce a low but sufficient accumulation of IL-2 mRNA and IL-2 secretion. A high concentration of A23187 (1.0 microM) did not show any synergism for the accumulation of IL-2R mRNA, membrane IL-2R expression and inhibited the proliferation of PMA co-stimulated T cells. It did, however, induce maximum accumulation of IL-2 mRNA and IL-2 secretion.

Human B cell function in responder and non-responder individuals. II. The role of T helper cells in promoting the PWM-induced B cell production of immunoprotein.

Sorted OKT4+ cells treated with pokeweed mitogen (PWM) and subsequently X-irradiated were used as a source of helper T cells to examine human T and B cell function. PWM-induced immunoprotein synthesis by human peripheral blood lymphocytes was the model used to study the cellular interactions. PWM was shown to induce helper T cell function which caused non-PWM treated B cells to secrete immunoglobulin. PBL from certain individuals could not be induced by PWM to secrete Ig therefore allogeneic co-cultures of helper T cells and B cells were examined to define the defective cell population. Ig synthesis in allogeneic cultures of T and B cells was always greater than that observed in autologous cultures when cells from responders were assayed. However, when allogeneic cultures were initiated using B cells from a responder and PWM treated T cells from a non-responder and examined for Ig synthesis, the B cell responses were markedly lower than seen in the autologous responder cultures. In addition, PWM activated helper T cells from a responder induced a significantly higher Ig synthesis by B cells from a non-responder. These observations indicate that PBL from individuals who do not respond in a PWM driven Ig synthesis assay have relatively normal B cell function but are deficient in helper T cell function.

Monoclonal antibody analysis of T-lymphocyte subsets in young and aged adults.

Eleven monoclonal antibodies identifying surface antigens present on human T lymphocytes were utilized to investigate the effects of advanced age on peripheral blood lymphocyte subsets. Both the proportion and number of lymphocytes recognized by five antibodies reactive with 'pan' T cell antigens (OKT3, OKT11, Leu4, T101 and Lyt3) decreased with age. The percentage of helper/inducer (OKT4+, Leu3a+) cells remained constant; however the proportion of Leu2a+, suppressor/cytotoxic cells declined. There was no change with age in the percent representation of OKT9+ or OKT10+ cells, nor in the ratio of helper/inducer to suppressor/cytotoxic cells (OKT4+/OKT8+ or Leu3a+/Leu2a+). Absolute numbers of helper/inducer (OKT4+, Leu3a+), suppressor/cytotoxic (OKT8+, Leu2a+), OKT9+ and OKT10+ cells were lower in elderly individuals as the result of lymphocytes constituting a lower percentage of the peripheral blood white cell population in this age group. While only small differences existed between the lymphocyte populations of young and aged men; aged women, compared to young women, had more dramatic shifts in their T cell populations. Comparison of antibodies putatively identifying similar (the same) functional groups of T cells demonstrated excellent correlation between the percentage of cells enumerated with the antibodies OKT3+: Leu4+ (r = .951), OKT4+: Leu3a+ (r = .914), OKT8+: Leu2a+ (r = .896), and in the ratio of helper/inducer to cytotoxic/suppressor OKT4+/OKT8+: Leu3a+/Leu2a+ (r = .926) cells.

Oxidative metabolism and bactericidal capacity of polymorphonuclear leukocytes from normal young and aged adults.

The ability of polymorphonuclear leukocytes (PMNs) from young and old individuals to reduce nitroblue tetrazolium, to kill Staphylococcus aureus in vitro, and to generate superoxide was determined. Investigation of PMNs from 202 humans, aged 26 to 95 years, failed to demonstrate an age relationship in their ability to reduce nitroblue tetrazolium. The ability of PMNs from 20 young (M age 34 years) individuals to kill S. aureus in vitro did not differ from cells from 18 elderly (M age 68 years) persons. Mean production of superoxide in response to stimulation with latex particles was, however, significantly lower (P less than .001) in cells from elderly adults. These results suggest a heterogeneity in any age-associated defect in PMN function. Several aspects of PMN function need to be evaluated in order to describe overall PMN function in the elderly.