T-Lymphocyte-mediated cytolysis as an excitatory process of the target. I. Evidence that the target cell may be the site of Ca2+ action.

Delivery of the lethal hit signal to target cells (TC) by cytolytic T lymphocyte (CTL) has traditionally been considered strictly dependent upon the presence of external Ca2+ [( Ca2+]ext) in the medium, but neither the role of Ca2+ nor its site of action (effector or target) have been known. We have observed that in different CTL/TC systems the requirement for [Ca2+]ext varies, depending on the target. Some TC, like leukemia L1210, are strictly dependent on [Ca2+]ext for lysis while others, like EL4 (and P815), are not.

Parotid hypertrophy with bulimia: a report of surgical management.

Benign hypertrophy of the salivary glands can occur in patients with anorexia nervosa. This enlargement has been related to nutritional deficiencies and bulimia, which is a form of episodic binge eating followed by vomiting. The surgical management of a patient with bulimia and benign bilateral parotid enlargement secondary to bulimia will be discussed.

Enumeration of lymphocyte-target cell conjugates by cytofluorometry.

Using fluorescein-labeled effector lymphocytes and tetramethyl rhodamine-labeled target cells a cytofluorometric method is described for the detection and quantification of lymphocyte-target cell cluster (conjugate) formation. Conjugation levels measured by cytofluorography correspond well with those scored microscopically. The method has so far been used successfully to monitor conjugate formation by specifically sensitized cytotoxic T lymphocytes (CTL).

How T lymphocytes kill infected cells.

Cytolytic T lymphocytes (CTL) are primary immune effector cells involved in allograft rejection, virus infection and, possibly, tumour immunity. This article is concerned primarily with their in vivo functions and with the mechanism whereby they bind to, and kill, target cells in vitro. A working hypothesis viewing CTL-mediated target cell lysis as the end result of CTL-induced stimulatory exhaustion of the target cell is discussed.

Antigen/mitogen induced cytolytic activity and IL-2 secretion in memory-like CTL-hybridomas.

Memory-like monoclonal CTL hybridomas, derived from fusion of the AKR thymoma BW5147 with secondary CTL generated in vivo or in MLC cultures, have been used to study the mechanism whereby antigen/mitogen induces anamnestic CTL responses. Specifically, we have asked whether induction of cytolytic activity can be promoted by an antigenic/mitogenic signal without involvement of IL-2 receptors, IL-2, or other extrinsic factors. We have found that antigen/lectin alone can trigger the cytolytic potential of the hybridomas and induce IL-2 secretion.

Immune cytolysis viewed as a stimulatory process of the target.

Humoral and cellular mechanisms of immune cytolysis, as effected by antibody and complement (Ab + C') or by cytolytic T lymphocytes (CTL), have traditionally been considered the end result of early but terminal membrane damage, in turn causing colloid-osmotic lysis of the target cell. A comprehensive theory explaining and relating known prelytic cellular events to subsequent membrane damage is lacking, nor is there a specific picture as to the role and mode of action of Ca2+, which appears to be involved in both complement- and cell-mediated cytolysis (C'MC and CMC, respectively). Recent studies are in support of the view that both Ab + C' and CTL induce a comparable series of prelytic events, in the TC, initiated by membrane depolarization, which in turn bring about voltage-dependent Ca2+ influx or its intracellular release.

Selective binding of concanavalin A to target cell major histocompatibility antigens is required to induce nonspecific conjugation and lysis by cytolytic T lymphocytes in lectin-dependent cytotoxicity.

The exquisite immunological specificity of cytotoxic T lymphocytes-target cell (CTL-TC) conjugation and lysis is overridden in the presence of certain plant lectins. The role of concanavalin A (Con A) in lectin-dependent, CTL-mediated cytolysis (LDCC) has been investigated. Papain-treated TC are refractory to LDCC, but regain susceptibility following a 3-hr incubation without the enzyme.

Memory CTL-hybridoma: a model system to analyze the anamnestic response of cytolytic T lymphocytes.

We have previously described monoclonal CTL-hybridomas growing continuously in culture in the absence of a known antigenic stimulus or growth-promoting factor(s), exhibiting specific anti-H-2Db killing activity in vitro after a distinct 2-hr lag period before the onset of lysis. Here we provide evidence indicating that the hybridoma Md 26.15 represents "memory" CTL, and we examine the mechanism whereby they respond to antigen/mitogen.

The pathway of lectin-mediated lymphocytotoxicity by Con A-coupled Sepharose beads.

Soluble concanavalin A (Con A) can effectively mediate nonspecific target cell lysis by cytolytic T lymphocytes (LDCC). Because Con A bound to Sepharose beads (Con A-Seph) is also effective, it has been concluded by Z. K.

Prelytic reduction of high-energy phosphates induced by antibody and complement in nucleated cells. 31P-NMR study.

Using 31P-NMR spectroscopy, we have investigated possible involvement of metabolic processes in the lysis of nucleated cells induced by low levels of antibody to cell surface antigens and complement. Within 10 min of antibody plus complement attack, before onset of overt lysis, we have observed a marked, selective reduction in the intracellular content of phosphocreatine and adenosine triphosphate (ATP). A longer attack is accompanied by total depletion of either phosphocreatine or ATP in residual cells which preserved other phosphate compounds.

Modulation of cell-mediated cytotoxicity function after alteration of fatty acid composition in vitro.

Fatty acids incorporated into cytotoxic T lymphocytes (CTL) during in vitro stimulation can enhance or inhibit the subsequent expression of cell-mediated cytotoxicity, depending on the class of fatty acid. Unsaturated fatty acids enhance cytolysis, whereas saturated fatty acids inhibit it. The effects of fatty acids on cytolysis can be mediated in the absence of cell division, thus eliminating relative clonal amplification or contraction as a basis for the observed effects.

An acoustic analysis of the effects of surgical therapy on voice quality.

An automated computer system was used to measure changes in vocal quality resulting from laryngeal surgery. Five acoustic parameters were computed and seven listeners made judgments on vowel samples recorded before and after surgery from 37 patients. Presurgery and postsurgery changes in the five acoustic measures were compared with the perception of change in vocal harshness.

T lymphocyte-mediated cytolysis. III. Delineation of mechanisms whereby mitogenic and non-mitogenic lectins mediate lymphocyte-target interaction.

We have investigated the mechanism(s) by which mitogenic (concanavalin A [Con A], phytohaemagglutinin [PHA] and Lens culinaris agglutinin [LCA]) and non-mitogenic (soybean agglutinin, peanut agglutinin, wheat-germ agglutinin and pokeweed mitogen) lectins mediate, non-specifically, lectin-dependent lymphocytotoxicity (LDCC). We show that non-mitogenic lectins are ineffective mediators of LDCC, due to their inability to mediate effective binding of effector cytotoxic T cells (EC) and target cells (TC), and not to their failure to 'activate' TC-bound EC, as proposed before. Evidence is presented that in LDCC Con A and PHA exert their primary effect(s) by affecting the TC rather than the EC.

Specific lysis of antigenically irrelevant cells by cytotoxic T lymphocytes upon insertion of appropriate antigens into the target cell plasma membranes.

The importance of the membrane milieu to functional presentation of target cell (TC) antigens to cytotoxic T lymphocytes (CTL) was investigated by examining the interaction of CTL with TC plasma membrane (PM) fractions, in isolated form or integrated into antigenically irrelevant TC. Isolated ascitic vesicles, microsomes, and purified PM, containing serologically defined alloantigens that have been implicated as the relevant TC antigens, effectively, yet nonspecifically, inhibited the binding and lysis of TC by CTL. The same PM fractions, when inserted into antigenically irrelevant TC via vesicles containing Sendai virus components, rendered the TC susceptible to CTL-mediated lysis directed against the inserted antigens.

Monoclonal cytotoxic T lymphocyte hybridomas capable of specific killing activity, antigenic responsiveness, and inducible interleukin secretion.

We have recently described the production of cytotoxic T lymphocyte (CTL) hybridomas that grow continuously in culture, exhibiting constitutive, allospecific (anti-H-2b) killing activity. We now report on the response of these monoclonal CTL hybridomas to specific antigen (H-2Db) and to mitogenic lectins. Both specific antigen and T cell mitogens enhance hybridoma-mediated specific target cell killing.

Cytotoxic T-lymphocytes. How do they function?

The central theme of this work has been the roles of the CTL receptor and of MHC-proteins in CTL recognition and lysis. A major conclusion that may be deduced from the work presented here is that one CTL receptor is responsible for both target cell recognition and lysis. Although their function as recognitive structures is well established, involvement of MHC-proteins in the events that follow recognition has not been investigated in detail.

Spatial relationships of microtubule-organizing centers and the contact area of cytotoxic T lymphocytes and target cells.

Specific binding (conjugation) of cytotoxic T lymphocytes (CTL) to target cells (TC) is the first step in a multistage process ultimately resulting in dissolution of the TC and recycling of the CTL. We examined the position of the microtubule organizing center (MTOC) of immune CTL bound to specific TC. Immunofluorescence labeling of freshly prepared CTL-TC conjugates with tubulin antibodies indicated that the MTOC in essentially all conjugated CTL but not in the conjugated TC were oriented towards the intercellular contact site.

A common role for target cell histocompatibility antigens in both nonspecific and specific T lymphocyte-mediated cytolysis.

We have investigated the role of target cell major histocompatibility complex antigens (MHC-Ag) in nonspecific lectin-dependent lymphocyte-mediated cytolysis (LDCC). In contrast to previous reports, we provide evidence that in LDCC the lectin Concanavalin A (Con A) does not mediate lysis by simply bridging cytotoxic T lymphocytes (CTL) and targets via cell surface sugars or by activating the lytic function of CTLs attached to targets via the lectin. Lysis occurs when target cells are pretreated with lectin, but not when CTL are pretreated.

T lymphocyte-mediated cytolysis. I. A common mechanism for target recognition in specific and lectin-dependent cytolysis.

In this and the accompanying paper we examine the nature of the interactions between effector cells and target cells leading to lysis in T cell-mediated cytolysis reactions. In the first paper, we re-examine the role of lectin (Con A) in the process of lectin-dependent cell-mediated cytotoxicity (LDCC). Lectin has generally been thought to act simply as a bridge between the cytotoxic effector cell (EC) and the target cell (TC), thus bypassing the need for receptor-antigen interaction and accounting for the nonspecific character of this lytic reaction.

T lymphocyte-mediated cytolysis. II. Role of target cell histocompatibility antigens in recognition and lysis.

Although compelling genetic and serologic evidence implicate target cell (TC) MHC antigens in specific cytotoxic T lymphocyte (CTL)-TC interaction leading to lysis, it is not entirely clear whether TC recognition through an MHC determinant(s) is a prerequisite for lysis to occur. In fact the finding that both specific and nonspecific TC are lysed equally well in lectin-dependent cell-mediated cytotoxicity (LDCC) challenges the necessity for TC MHC involvement in the cytolytic process beyond providing the basis for specificity in direct (nonlectin-dependent) CTL-mediated lysis. In the present paper we present evidence suggesting that even in nonspecific LDCC, as well as in nonspecific lymphocyte-mediated lysis of TC oxidized by periodate treatment or by galactose oxidase (ODCC), TC MHC components are required for lytic interactions with cytotoxic effector cells.

Tumor cell destruction by cytotoxic T lymphocytes: the basis of reduced antitumor cell activity in syngeneic hosts.

Tumor overgrowth in spite of an ongoing antitumor immune response may be due to a basic immunologic defect in T cell-mediated responses against the potentially immunogenic tumor cells. To further understand T cell-mediated responses in syngeneic tumor-host systems, we have analyzed the interaction of cytotoxic T lymphocytes (CTL) with syngeneic tumor cells and have compared it with CTL-allogeneic tumor cell interaction. The major conclusions of this study are: 1) Syngeneic and allogeneic CTL lyse target cells through a similar mechanism.