Membrane markers, target cell specificity, and sensitivity to biological response modifiers distinguish human natural cytotoxic from human natural killer cells.

In the present report, we provide evidence for the distinct existence of a human natural cytotoxic (HNC) cell. This HNC cell can be identified by the monoclonal antibody HNC-1A3 and by the absence of the T10 antigen, other antigenic markers being shared, at least in part, with natural killer (NK) cells, T cells, or monocytes. In addition, the HNC cell preferentially kills the MA-160 target, the herpes simplex virus-1-infected MA-160 cell line, and the two human tumor cell lines HEp-2 and HF-2. It has weak lytic activity against the NK-sensitive K562 cell line or its relatively NK-resistant clone I subline. The cytotoxic activity of the HNC cell is not augmented by interferon but is markedly enhanced by interleukin 2 and by a measles-virus-induced factor (MVF). Furthermore, it is not inhibited by cyclosporin A (CsA), in contrast to NK cell cytotoxicity against the K562 target cell line which is augmented by interferon, inhibited by CsA, and not affected by MVF. These data suggest that spontaneously cytotoxic cells may belong to more than one subset of human lymphocytes, and that HNC cells may be defined in man using membrane markers, target cell specificity, and sensitivity to biological response modifiers.

The neuropathology of "typical" Friedreich's ataxia in Quebec.

We present the pathological data from the autopsies performed on 6 Friedreich's disease patients since the start of the Quebec Cooperative Study. All patients met the strict diagnostic criteria of the QCSFA. The anatomical lesions found in the peripheral and central nervous system were similar in all 6 cases and do not differ from those described in the literature. The clinical findings correlate closely with the histological lesions found in the peripheral nervous system and spinal cord. The evidence of segmental demyelination and remyelination in the spinal ganglia and posterior roots further supports the dying-back axonopathy hypothesis.

Human natural cytotoxic lymphocytes: definition by a monoclonal antibody of a subset which kills an anchorage-dependent target cell line but not the K-562 cell line.

A monoclonal mouse antibody (HNC-1A3) which defines a subset of human lymphocytes with natural cytotoxic activity was produced and studied. HNC-1A3+ cells represent 12 +/- 3% of peripheral blood mononuclear leukocytes. When sorted out using a fluorescence-activated cell sorter, they consist of 60% small lymphocytes, 35% large (predominantly agranular) lymphocytes, and 5% monocytes. They contain 30 +/- 6% E-rosette-forming cells, 6 +/- 1% OKT4+ cells, 17 +/- 6% OKT8+ cells and less than 2% OKT10+ or Leu-7 (HNK-1)+ cells. They are responsible for most of the natural cytotoxic activity against the MA-160 prostatic adenoma cell line but mediate an insignificant amount of cytotoxicity against the NK prototype target K562 cell line. Conversely, Leu-7+ cells which mediate most NK activity against K562 are weakly active against MA-160. Our data suggest a heterogeneity among leukocytes mediating natural cytotoxicity, with restricted specificities for the recognition sites on target cells.

In-vitro-induced human T cells cytotoxic against herpes-simplex-virus-infected targets: modulation by theophylline of the induction and effector stages.

We have shown in previous studies that the cytotoxic effector cells in in-vitro-induced cytotoxicity against herpes-simplex-virus-infected targets are principally T gamma cells and that they derive from theophylline-resistant T mu cells. In the present work, we studied the effect of theophylline on the induction and expression of cytotoxic activity in T-cell subsets. When T cells were prefractionated before the induction phase, the theophylline-resistant (Thr) subset, as determined by E-rosetting, was unaffected by the presence of theophylline during sensitization, whereas T mu and unfractionated T cells were inhibited. On the other hand, when theophylline was present during the cytotoxicity assay, all T-cell subsets were similarly affected. Studies of kinetics revealed that a short preincubation with the drug had an enhancing rather than an inhibitory effect on both the proportions of T gamma and Thr and on their cytotoxic activity at 3 days.

Natural cytotoxic cell activity linked to time of recurrence of herpes labialis.

Peripheral blood mononuclear leucocytes from patients with recurrent oral herpes labialis showed an enhanced spontaneous cytotoxic activity against HSV-1 infected target cells during the acute episode. A heightened cytotoxicity persisted for several weeks during prospective follow-up study of the donors, but fell to low levels during the last week before the next episode of herpes labialis. A correlation between natural cytotoxicity against HSV infected targets and pre-recurrence intervals was noted (r = 0.715, P less than 0.05). In parallel, recurrence of herpes labialis was accompanied by a marked increase in the percentage of T cells with Fc IgG receptors and in the percentage of natural cytotoxic lymphocytes, as defined by a newly described monoclonal antibody, HNC-1A3. Both these populations were significantly decreased during the last week before the next herpes labialis episode, suggesting a role for these cells in defence mechanisms involved in anti-HSV immunity.

Human natural cytotoxic cells: activation by a measles virus-induced lymphocyte factor which increases the expression of the HNC-1A3 antigen.

When human lymphocytes were exposed to measles virus antigen or to SSPE virus-infected cells, their cytotoxic activity against uninfected MA-160 cells was markedly enhanced. In contrast, mumps virus or herpes simplex virus-infected cells did not show such an enhancing effect and were rather inhibitory. SSPE cells and measles virus antigen, but not mumps-virus-infected cells or mumps virus antigen, also induced a two-fold increase in the number of lymphocytes bearing the HNC-1A3 membrane antigen, which we recently reported to be associated with a natural cytotoxic cell population. Pretreatment of SSPE cells or measles virus antigen with anti-measles antibody abolished the enhancing effect. Heat-treating the cells or the antigen at 56 degrees C for 30 min similarly abolished the effect. Supernatants of lymphocyte-SSPE cell cocultures were also effective in enhancing natural cytotoxicity. The soluble factor was a low molecular weight dialyzable molecule which was unaffected by boiling or trypsinization. It was released within 4 hours of coculture even in the presence of cycloheximide or following irradiation. Neither interferon nor leukotriene B4 appeared to be responsible for this enhancement. Virus-lymphocyte interaction may thus enhance natural cytotoxic cell activity through the rapid production or release of a virus-induced small molecular weight lymphocyte factor.

Suppression of the lymphoproliferative response by positively charged liposomes.

The efficiency of positively-charged liposomes as immunomodulators was investigated in vitro using a lymphoproliferative response assay on cultured human lymphocytes challenged either with different polyclonal activators or with actin, a cytoskeletal protein of poor immunogenicity. Our results indicate that these liposomes suppress the [3H]thymidine incorporation in lymphocyte cultures and inhibit the mitogen-induced proliferation without, however, exhibiting significant cytotoxicity.

Activation of class II gene transcription by regulatory factors is potentiated by a novel activity.

A novel activity (USA) stimulated activator-dependent transcription in a reconstituted system in conjunction with natural TFIID, resulting in 10- to 50-fold levels of induction by regulatory factors. USA mediated a modest induction by USF in conjunction with either recombinant human TFIID, intact yeast TFIID, or the evolutionarily conserved C-terminal portion of yeast TFIID. Upon further purification, USA was resolved into two components that had opposite effects on core promoter activity and that in combination potentiated activator function. Gel mobility shift experiments indicated physical interactions between the inhibitory activity and TFIID, suggesting that the additional components (cofactors) associate with the preinitiation complex both to reduce promoter activity in the absence and to increase promoter activity in the presence of transcriptional activators.

Comparative effects of receptor inactivation, 17 beta-estradiol and pertussis toxin on dopaminergic inhibition of prolactin secretion in vitro.

Akin to receptor inactivation with phenoxybenzamine (PBZ) (1 microM, 1 hr), treatment of anterior pituitary cells with 17 beta-estradiol (10 nM, 3 days) right-shifted the dose-response curve for inhibition of prolactin (PRL) secretion by the full agonist R-(-)-N-n-propylnorapomorphine (NPA) and reduced the maximal effect [EC50 (pM) and percent maximal effect: control, 25.4 and 81.2; PBZ, 115.3 and 57.9; 17 beta-estradiol, 358 and 58.6]. PBZ treatment of 17 beta-estradiol-pretreated cultures further reduced the maximal response but did not alter the EC50. Plots of receptor occupancy vs. response indicated a large receptor reserve for NPA (approximately 60%) in control cultures but its abolition by 17 beta-estradiol. 17 beta-Estradiol pretreatment elicited identical rightward shifts (4.5-fold) and similar reductions in maximal PRL inhibition by quinpirole and (+)-3-PPP, although these drugs were partial agonists with dissimilar efficacies relative to NPA (0.61 and 0.12, respectively) at presynaptic striatal D2 receptors. However, receptor inactivation experiments with (+)-3-PPP and quinpirole, and subsequent comparison of receptor occupancy vs. response plots, demonstrated that the relative efficacies of quinpirole and (+)-3-PPP were reversed in the striatum and anterior pituitary. In striatum, half-maximal response to quinpirole and (+)-3-PPP required 6.2 and 30% receptor occupancy, respectively, whereas 25.6 and 9.6% occupancy was required in the pituitary. Pertussis toxin treatment (10 ng/ml, 24 hr) produced large shifts in the dose-response curves for all three agonists (8.4-21.9-fold), but was distinguished from the effects of both PBZ and 17 beta-estradiol by a significant (P < .001) decrease in the slope factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic control of autoimmune myocarditis mediated by myosin-specific antibodies.

Autoimmune disease involves both the development of autoreactivity and the expression of organ damage, and susceptibility is genetically complex. We recently reported that in autoimmune myocarditis susceptibility to antibody-mediated cardiac injury is strain specific. DBA/2 mice develop myocarditis following administration of myosin-specific antibody, while BALB/c mice do not. This susceptibility appears to be controlled by expression of myosin in the myocardial extracellular matrix. CByD2F1 mice are both resistant to induction of myocarditis and do not demonstrate extracellular myosin, indicating a recessive genetic component to these traits. A backcross analysis of susceptibility using DBA/2xCByD2F1 mice revealed a locus on chromosome 12 that is strongly linked with myocarditis. In male mice there was a second region on chromosome 1 that also contributes to disease susceptibility. However, genetic susceptibility in both female and male mice was genetically complex. This study demonstrates that the genetic basis of tissue injury can be analyzed separately from the genetic basis of autoreactivity. Future studies will determine whether the genetic factors identified in this study are also involved in susceptibility to rheumatic fever.