Suicide attempts and impulse control disorder are related to low cerebrospinal fluid 5-HIAA in mentally disordered violent offenders

OBJECTIVE

The aim of this study was to investigate the relationship between low cerebrospinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA) and aggressive acts in mentally disordered violent offenders.

METHOD

CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid and 4-hydroxy-3-methoxyphenyl glycol were measured in 35 drug-free men convicted of homicide and currently undergoing forensic psychiatric investigation in a high security hospital.

RESULTS

The mean metabolite concentrations in the homicide offenders did not differ from those of age- and body-height matched male control subjects. One-third of the murderers had made one or several suicide attempts, and their mean concentration of spinal fluid 5-HIAA was significantly lower than that of the remaining murderers. Subjects with impulse control disorder also had lower mean CSF 5-HIAA. A consistent pattern of higher CSF 5-HIAA in subjects with more self-reported anxiety traits was observed.

CONCLUSION

The association between serotonin and suicidal behaviour holds for yet another subject group. Determining CSF 5-HIAA might be worth while in the routine assessment of psychiatrically ill homicide offenders.

Prevention of superantigen-induced tolerance in vivo by interleukin-2 treatment

Injection of the superantigen staphylococcal enterotoxin A (SEA) activates both CD4+ and CD8+ T cells expressing certain families of T cell receptor (TCR) variable-region beta (V beta) chain. T cells respond with profound cytokine production and induction of cytotoxicity. Repeated injections, however, cause deletion and anergy of both CD4+ and CD8+ T cells, resulting in reduced frequency of SEA-responsive cells TCR-V beta11+ as well as reduced cytokine levels in serum upon challenge with SEA. Exogenous interleukin-2 (IL-2) in vivo rescued SEA-responsive CD4+ and CD8+ cells from SEA-induced deletion and/or increase expansion of SEA-primed cells as well as preventing downregulation of endogenous IL-2 production in vivo. Combined treatment with SEA and IL-2 also superinduced production of important cytokines for the cytotoxic function of T cells, tumour necrosis factor alpha, interferon gamma and IL-6, on a cellular level. These studies show that continuous stimulation with IL-2 in vivo could be useful for superantigen-based immunotherapy by induction of excessive T cell activation and by prevention of the development of T cell deletion and anergy.

Prevention of superantigen-induced down-regulation of T-cell mediated cytotoxic activity by IL-2 in vivo

Administration of staphylococcal enterotoxin A (SEA) to mice induces profound activation, cytokine production and cytotoxic activity of both CD4+ and CD8+ T cells, but subsequently activated cells are deleted or become anergic. This study demonstrates that administration of interleukin-2 (IL-2) can prevent sea-induced hyporesponsiveness in CD8+ cytotoxic T lymphocytes (CTL). Repeated injections with sea every fourth day resulted in severely reduced cytotoxic activity in the spleen, which correlated with a reduced number of sea-responsive T-cell receptor (TCR)-V beta 11+ CD8+ cells. Studies of purified TCR-V beta 11+ CD8+ cells showed that they possessed intact cytotoxic activity per cell compared with cells from mice given a single injection of SEA, indicating that deletion was the main mechanism for the reduced cytotoxic activity. Combined treatment with SEA and IL-2 increased the number of cytotoxic cells in the spleen after each SEA injection and prevented the down-regulation of cytotoxic activity. Increased cytotoxic activity could be related to increased number and proliferation of CD8+ IL-2R alpha + cells, suggesting that administration of IL-2 maintained IL-2 responsiveness among CD8+ cells. Studies of sorted TCR-V beta 11+ CD8+ cells demonstrated that combined treatment with SEA and IL-2 also increased cytotoxic activity per cell compared with treatment with SEA alone. Taken together, IL-2 administration in vivo augmented SEA-induced expansion of T cells as well as the cytotoxic activity per CTL, and prevented SEA-induced cell deletion.

Enhanced and prolonged efficacy of superantigen-induced cytotoxic T lymphocyte activity by interleukin-2 in vivo

The bacterial superantigen, staphylococcal enterotoxin A (SEA) activates T cells with high frequency and directs them to lyse MHC-class-II-expressing cells in superantigen-dependent cell-mediated cytotoxicity (SDCC). Treatment of mice with SEA induced strong CD8+ T-cell(CTL)-mediated SDCC, as well as abundant cytokine production from CD4+ and CD8+ T cells. However, both cytotoxicity and cytokine release were transient. In contrast, combined treatment with SEA and recombinant interleukin-2 (rIL-2) increased peak levels and maintained CTL activity. These effects were concomitant with an increased number of SEA-reactive V beta 11+ T cells. Both the CD4+ and CD8+ populations contained higher frequencies of cells expressing IL-2 receptor (IL-2R) alpha beta, which suggests that continuous IL-2R signaling preserves its high expression and subsequently prevents loss of growth factor signals necessary for expansion of T cells. Although IL-2R expression was increased among both CD4+ and CD8+ cells, only the cytotoxic function of CTL, but not cytokine production from either CD4 or CD8, was augmented. These findings demonstrate that treatment with rIL-2 potentiates superantigen-induced cytotoxicity and maintains high CTL activity. rIL-2 might therefore be useful in improving superantigen-based tumor therapy.

Combined activation of murine lymphocytes with staphylococcal enterotoxin and interleukin-2 results in additive cytotoxic activity

This report demonstrates that in vitro activation of murine spleen cells with interleukin-2 (IL-2) or the bacterial superantigen staphylococcal enterotoxin A (SEA) results in different patterns of activation and function of cytotoxic cells. Lymphokine-activated killer activity and antibody-dependent cellular cytotoxicity (ADCC) are mainly mediated by IL-2 activated natural killer (NK) cells. SEA is the most powerful T cell mitogen known so far and retargets cytotoxic T lymphocytes (CTL) to tumors expressing major histocompatibility complex (MHC) class II in staphylococcal-enterotoxin-dependent cellular cytotoxicity (SDCC). Culture of mouse spleen cells with SEA led to expansion and activation of T cells, which demonstrated strong SDCC activity and some NK-like cytotoxicity after 5 days in culture. Cell sorting revealed that both CD8+ and CD4+ T cells mediated SDCC but the former were more effective. Phenotypic analysis showed that SEA preferentially stimulated and expanded T cells expressing T cell receptor V beta 11, in particular CD8+ T cells. Combined activation with SEA and IL-2 resulted in simultaneous induction of T and NK cell cytotoxicity. Moreover, IL-2 had additive effects on SEA-induced SDCC. Combined treatment with SEA and IL-2 might therefore be an approach to induce maximal cytotoxicity against tumors and to recruit both T and NK cells in tumor therapy.

Platelet monoamine oxidase activity in mentally disordered violent offenders

The activity of monoamine oxidase (MAO) in blood platelets among criminals undergoing forensic psychiatric examinations was studied. As compulsiveness, disturbed perceptions of reality, etc. are states not known to be related to MAO and yet possibly cause aggressiveness and violence among psychotic patients, we divided the patients into 2 groups, psychotic and nonpsychotic offenders. There was lower MAO activity among violent offenders than among nonviolent offenders. The difference between the violent and nonviolent offenders became greater when the subjects with a history of psychosis were removed. Furthermore, in the group of psychotic offenders, there was no statistical difference between violent and nonviolent individuals in this regard.

Analysis of the murine lymphokine-activated killer (LAK) cell phenomenon: dissection of effectors and progenitors into NK- and T-like cells

Murine as well as human lymphokine-activated killer (LAK) cells have been reported to have several characteristics of T lymphocytes and to be clearly distinct from natural killer (NK) cells. The present study of murine LAK cells showed that cytotoxic cells generated in the presence of interleukin 2 IL 2 were heterogeneous with respect to cell surface markers of progenitor as well as effector cells. Negative selection of cells with antibodies and complement or positive selection by fluorescence-activated cell sorting unequivocally showed that LAK effector cells consisted of at least two clearly distinct populations, the relative contribution of which was dependent on donor organ and target cells studied. Approximately 40% of the cytotoxic activity of spleen-derived effector cells active against the NK-resistant targets EL-4 or MCA-5 was eliminated by treatment with antibodies to the NK-markers asialo-GM1 and NK 1 (NK-LAK). Approximately 60% of cytotoxic activity was associated with cells expressing the T cell marker Lyt-2, lacked NK 1, and was lacking or expressed only small amounts asialo-GM1 (T-LAK). The NK-LAK cells were of greater importance for the cytotoxic activity against the standard NK target YAC-1, although T-LAK cells also excerted significant cytotoxicity against this cell line. Limiting dilution analysis estimated that the minimal frequency of precursors developing into cells with cytotoxic activity against EL-4 was 1/6700 in spleen and 1/4200 in peripheral blood. The frequency of cells developing into cytotoxic effectors against YAC-1 cells was 1/3700 and 1/1450 in spleen and peripheral blood, respectively. Depletion of progenitor cells from spleen or peripheral blood expressing NK 1 or Lyt-2 by treating the cells with antibodies to these structures and complement indicated that NK-1-expressing cells were the dominating progenitor of the LAK cells irrespective of target cells used. Culture of murine lymphoid cells from spleen or peripheral blood with high concentrations of IL 2 results in the emergence of two different killer cell populations with phenotypic similarities to NK and T cells, respectively, both being able to kill targets resistant to resting NK cells. In contrast to numerous earlier reports, we concluded that LAK cells are heterogeneous with respect to surface markers, with a major population of LAK cells apparently representing IL 2-activated cells expressing cell surface markers associated with NK cells.

Analysis of the murine lymphokine-activated killer (LAK) cell phenomenon: dissection of effectors and progenitors into NK- and T-like cells

Murine as well as human lymphokine-activated killer (LAK) cells have been reported to have several characteristics of T lymphocytes and to be clearly distinct from natural killer (NK) cells. The present study of murine LAK cells showed that cytotoxic cells generated in the presence of interleukin 2 IL 2 were heterogeneous with respect to cell surface markers of progenitor as well as effector cells. Negative selection of cells with antibodies and complement or positive selection by fluorescence-activated cell sorting unequivocally showed that LAK effector cells consisted of at least two clearly distinct populations, the relative contribution of which was dependent on donor organ and target cells studied. Approximately 40% of the cytotoxic activity of spleen-derived effector cells active against the NK-resistant targets EL-4 or MCA-5 was eliminated by treatment with antibodies to the NK-markers asialo-GM1 and NK 1 (NK-LAK). Approximately 60% of cytotoxic activity was associated with cells expressing the T cell marker Lyt-2, lacked NK 1, and was lacking or expressed only small amounts asialo-GM1 (T-LAK). The NK-LAK cells were of greater importance for the cytotoxic activity against the standard NK target YAC-1, although T-LAK cells also excerted significant cytotoxicity against this cell line. Limiting dilution analysis estimated that the minimal frequency of precursors developing into cells with cytotoxic activity against EL-4 was 1/6700 in spleen and 1/4200 in peripheral blood. The frequency of cells developing into cytotoxic effectors against YAC-1 cells was 1/3700 and 1/1450 in spleen and peripheral blood, respectively. Depletion of progenitor cells from spleen or peripheral blood expressing NK 1 or Lyt-2 by treating the cells with antibodies to these structures and complement indicated that NK-1-expressing cells were the dominating progenitor of the LAK cells irrespective of target cells used. Culture of murine lymphoid cells from spleen or peripheral blood with high concentrations of IL 2 results in the emergence of two different killer cell populations with phenotypic similarities to NK and T cells, respectively, both being able to kill targets resistant to resting NK cells. In contrast to numerous earlier reports, we concluded that LAK cells are heterogeneous with respect to surface markers, with a major population of LAK cells apparently representing IL 2-activated cells expressing cell surface markers associated with NK cells.

Functionally involved cell surface antigens on murine lymphokine activated killer cells

To investigate the possible involvement of some cell surface structures on lymphoid cells in the functional activity of lymphokine activated killer (LAK) cells, a number of monoclonal antibodies (Mab) against such structures was studied for their ability to inhibit LAK activity in a standard cytotoxicity assay against the natural killer-insensitive target cell EL-4. Almost complete inhibition of LAK activity resulted from incubation with antibodies to the LFA-1 antigen, while blocking of the Lyt 2 antigen reduced cytotoxic activity about 50%. Mab to T-200 gave a weak and inconsistent inhibitory activity, while antibodies to Thy 1, L3T4, IL-2 receptor and MHC class I antigens were without effect. Mab to LFA-1 and Lyt 2 inhibited LAK activity towards EL-4, YAC-1 and differentiated F-9 teratocarcinoma cells, but did not affect LAK-mediated killing of undifferentiated F-9 cells. Experiments with separate preincubation of effector and target cells revealed that both LFA-1 and Lyt 2 inhibited LAK activity at the effector cell level only.