Early detection and specificity analysis of human cytolytic T lymphocyte (CTL) colonies generated in soft agarose culture: a potential assay for definition of CTL defined (CD) determinants

Interleukin-2 liposome inhalation therapy is safe and effective for dogs with spontaneous pulmonary metastases

BACKGROUND

Systemic in vivo toxicity of interleukin-2 (IL-2) has been problematic. Antineoplastic activity of IL-2 has been modest. The authors have previously demonstrated the biologic activity and safety of aerosols of IL-2 liposomes in normal dogs. They now report objective regression of naturally occurring pulmonary metastases in dogs after 1 month of nebulized IL-2 liposome therapy.

METHODS

Dogs with pulmonary metastases (n = 7) and primary lung carcinoma (n = 2) were treated with aerosols of IL-2 liposomes. Response to therapy was monitored with serial chest radiographs. Effector populations, collected by bronchoalveolar lavage (BAL) and from heparinized whole blood, were assessed for cell type, immunophenotype, and tumor cytolytic activity. Immunogenicity of human IL-2 and human serum albumin (HSA) in dogs was assessed by immunofluorescence assay.

RESULTS

Two of four dogs with metastatic pulmonary osteosarcoma had complete regression of metastases; the regression remained stable for more than 12 and more than 20 months, respectively. One of two dogs with lung carcinoma had stabilization of disease for more than 8 months; the other had disease progression. Toxicity was minimal. BAL cell numbers increased more than fourfold (P = 0.01) and included significantly greater proportions and total numbers of eosinophils (P = 0.006) and lymphocytes (P = 0.008). Mean BAL effector lytic activity was significantly greater after 15 days of IL-2 liposome inhalation compared with pretreatment activity (P = 0.01); however, mean BAL lytic activity decreased after 30 days and was no longer significantly greater than pretreatment BAL lytic activity. No allergic reactions were associated with inhaled IL-2 liposome therapy. Canine antibodies against human IL-2 and HSA were detected in all dogs.

CONCLUSIONS

Pet dogs with naturally occurring pulmonary metastases and primary lung carcinomas accepted inhalation treatments easily. Nontoxic and effective treatment of pulmonary metastases of osteosarcoma is possible with nebulized IL-2 liposomes.

Gene expression in CD8 and CD4 T-cell populations following activation with the calcium ionophore A23187

We have hypothesized that functional maturation of T lymphocytes can be dissected into a series of discrete stages. For example, activation of T lymphocytes with the calcium ionophore A23187 drives CD8+ T cells to become dividing blasts, referred to as 'pre-effector' cells in that these blasts do not express cytolytic function but are driven by IL-2 to do so. Here we characterize via Northern blots the functional maturation of CD8+ and CD4+ T-lymphocyte populations which have been activated via A23187 followed by stimulation with IL-2. Previously we have reported that no detectable IL-2 was found in the supernatants of A23187-activated pre-effector blasts. However, these cells do express levels of IL-2 mRNA very similar to those of OKT3-activated blasts, from which IL-2 is easily detected in the supernatant. Translational control may account for these findings. A23187-activated CD8+ pre-effector blasts do not respond to stimulation with IFN-gamma nor do they express IFN-gamma mRNA following stimulation with IL-2. These observations suggest that IL-2 may be sufficient to stimulate maturation of these cells. Activation via A23187 results in lower expression of the proto-oncogene c-myb relative to that found in OKT3 activation. C-myb mRNA levels are higher in CD8+ than in CD4+ A23187-activated pre-effector blasts and the c-myb level in the CD8+ pre-effector blasts falls in response to IL-2. This decrease in c-myb mRNA coincides with an increase in proliferation, and the expression of cytolytic activity.

Role of cross-linking in stepwise activation of T cells

Activation of T cells is a complex process which we have hypothesized involves a series of functional intermediates possessing some, but not all, of the characteristics of fully functional effector cells. We have identified two such functional intermediates, the poised T cell (poTc) and the pre-effector T cell (peTc). poTc do not proliferate or mediate cytolytic activity but are responsive to help in the form of interleukin 2 (IL-2); peTc are proliferating cells which are not cytolytic. Here the role of T-cell receptor/CD3 complex cross-linking in generating these functional intermediates is examined and it is shown that cells can be driven to different stages of functional maturation depending upon the sequence of antibody binding to CD3 and cross-linking. Highly purified T cells can be activated to poTc stage if they are first labelled with the anti-CD3 monoclonal antibody OKT3 and then cross-linked with goat anti-mouse IgG-coated beads. If the OKT3 antibody is first bound to the IgG-coated beads and then added to highly purified T cells, peTc are generated. In both cases the intermediates can be driven to become fully functional effector cells by the addition of IL-2. Finally, by removing the OKT3-bound beads during the activation process, were are able to show that poTc and peTc are sequential intermediates along the same pathway of activation.

Molecular events in late stages of T-cell functional maturation

Peripheral blood lymphocytes activated with either the calcium ionophore A23187 or the combination of anti-CD2 monoclonal antibodies, 9.6 + VIT13, undergo blast formation and proliferation but do not develop cytolytic activity. These proliferating blasts, referred to as pre-effector blasts because they do not yet express cytolytic function, respond to stimulation with interleukin-2 (IL-2) by further proliferation and development of cytolytic activity, i.e. they become effector cells. Pre-effector blasts activated with 9.6 + VIT13, but not A23187-activated pre-effector blasts, also respond to stimulation with interferon-gamma (IFN-gamma) by becoming cytolytic effector cells. This report examines gene expression (by Northern blot analysis) in pre-effector blasts and during the transition from the pre-effector to the effector stage. The data presented here provide further support for the concept that A23187 activation drives T cells to become dividing blasts that are appropriately referred to as 'pre-effector' cells in that these blasts do not express transcripts for granzyme A or perforin mRNA but are driven by IL-2 to do so in parallel with the acquisition of cytotoxic function. Cells are apparently driven by 9.6 + VIT13 to a later stage of functional maturation than by A23187 activation; 9.6 + VIT13-activated pre-effector blasts express mRNA for both granzyme A and perforin, even though these blasts do not express cytolytic activity. Activation via A23187 results in lower expression of the proto-oncogene c-myb relative to that found in either 9.6 + VIT13 or OKT3-activated cells.

Cytotoxic T lymphocytes: blocked differentiation at the 'poised' stage

The effect of different concentrations of phorbol myristate acetate (PMA) on the development of cytotoxic cells was studied. PMA was selectively able to prevent the development of cytotoxic cells in a mixed leucocyte culture, while allowing the responding cells to proliferate. The higher concentration of PMA (10(-5)M) blocked both direct cytotoxicity and lytic activity in the presence of lectin, while the lower concentration (10(-8) M) only prevented direct lytic function. The removal of PMA and subsequent addition of recombinant interleukin 2 (IL-2) or IL-2-containing supernatants effectively reversed the effect of PMA with recovery of antigen-specific lytic function of cells treated with 10(-8) M, while cells treated with 10(-5)M PMA only recovered lectin-dependent cytotoxic ability.

Allospecific proliferative human T-cell clones acquire the cytotoxic effector function after three months in culture, in IL-2 conditioned medium

Allostimulated T lymphocytes were cloned by micromanipulation and expanded in IL-2 conditioned medium. Three T3+,T4+,T8-, clones called BJ1, BJ4, and BJ37, were extensively studied. The BJ1 cells were able to proliferate and kill the specific target. The BJ4 and BJ37 cells were able to proliferate with the specific restimulator but could not kill even in lectin-dependent cell-mediated cytotoxic assay; however, they acquired the specific cytolytic activity in the 6-day culture when fresh irradiated autologous peripheral blood mononuclear cells as feeder cells were added to the specific irradiated Epstein-Barr virus transformed cell line, in the presence of recombinant IL-2. This observation strongly suggested that the culture conditions could be involved in the differentiation of proliferative clones into cytotoxic T lymphocyte (CTL) clones, by the lymphokines, either present in the IL-2 conditioned medium or secreted by the mixed allogeneic irradiated feeder cells. Moreover, it was shown that the acquisition of the cytolytic function could be blocked by the monoclonal antibody LeoA1, previously described and which recognized the TLiSA1 structure involved in the CTL differentiation.

NO1: an HLA-DQw1-associated determinant present on loss mutants not expressing DQw1

We have used two monoclonal antibodies, FA and Tu39, and cloned cytotoxic T lymphocytes to study the immunogenetic control of an HLA-D region-encoded determinant(s) recognized by the Tc other than class I or DR or DQ. The Tc recognize a determinant associated with one (the A2) haplotype of LCL721 and are lytic to mutants of LCL 721 that have lost expression of all class I as well as the serologically defined DR and DQw specificities associated with, and presumably identical to, DPw2, the specificity encoded by the sensitizing (A2-B51) haplotype; these data provide the first evidence that FA recognizes the protein dimer presumably expressing the DPw determinant. Those Tc blocked by Tu39 recognized a determinant, referred to as NO1, that is not associated in the population with DPw2, but is found on some, but not all, DQw1-positive cells. We propose three possible explanations for these results. (i) There may be a class II product other than DP or those expressing the DR or DQ serologically defined specificities carrying NO1; such a product could be either as yet undescribed (E. Long has obtained information for an expressed and as yet undefined class II beta gene, personal communication) or a second expressed dimer of the DQ or DP families. (We assume that no DR genes of the A2 haplotype are expressed in these mutants. (ii) NO1 and DPw2 may be on the same molecule; to account for the lack of association of NO1 and DPw2 in the population, one might propose a mechanism such as gene conversion leading to expression of NO1.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss and re-acquisition of lytic function by cloned cytotoxic T lymphocytes: role of specific antigen and interleukin 2

We have previously reported the isolation of 2 human allospecific cytotoxic T-lymphocyte (CTL) clones that can undergo a reversible functional change from a highly lytic phase to a nonlytic quiescent phase and again to a lytic phase. The entire process was found to be regulated by recombinant interleukin 2 (rIL-2). We have now extended these studies in 3 ways. First, we show that specific alloantigens can also function as a signal to reactivate lytic function in the reverted CTL. However, in contrast to CTL reactivated with rIL-2, the antigen-reactivated CTL apparently fail to undergo subsequent cell division. Second, we have also found that this reversion phenomenon is not the same for all CTL tested, as 2 other CTL clones were found that did not revert to the non-lytic phase when cultured for up to 60 h in rIL-2-free medium. Third, the expression of Tac (IL-2 receptor) was also studied throughout the process of reversion and reactivation. rIL-2 added to the cell that had reverted to a non-lytic phase induced, an increase in the expression of Tac receptors during the reactivation phase, to levels greater than those expressed on cells continuously cultured in rIL-2-supplemented medium.

Analysis of human class II antigens by cloned cytolytic T cell reagents: a study using HLA loss mutant lymphoblastoid cell lines and monoclonal antibodies detecting the HLA-DP product(s)

We have utilized cloned T cell reagents and ionizing radiation-induced mutants of an HLA heterozygous lymphoblastoid cell line (LCL) to investigate the determinants detected by the cell-mediated lympholysis (CML) assay. Cells of an LCL clone, 721.501, an HLA haplotype loss mutant expressing the HLA-A2-Cw1-Bw51-DR1-Dw1-DQw1-DPw2-GLO haplotype were used as sensitizing cells for responder cells in vitro. "Cloned" reagents were generated by single-cell deposition of cells of a bulk reagent primed against 721.501 cells. Those clones were screened for cytolytic activity against HLA loss mutant targets (derived from LCL 721) of four different categories; HLA-A2 loss only, A2-Cw1-Bw51 loss, A2-Cw1-Bw51-DR1-DQw1 loss, and the entire HLA haplotype loss. Of 196 clones tested, 36 were cytolytic, including three anti-A2, five anti-Bw51/Cw1, 12 anti-DR1/DQw1, 13 anti-DP region associated with DPw2, and three of undetermined specificity, based on cytolytic patterns against the HLA loss mutant targets. Of 25 anti-HLA class II lytic clones, 23 (92%) fitted the characteristics of helper cell-independent cytolytic T cells (HITc), whereas only two of eight (25%) anti-class I clones were HITc. The 13 anti-DP region clones were divided into three subgroups defined by blocking by anti-FA and not Tü39 monoclonal antibodies (MoAb), by Tü39 and not anti-FA, and by both MoAbs.

Cellular basis of anti-SB response

Cloning of cells allosensitized in vitro against SB1, SB2, and SB3 antigens was performed by micromanipulation. One hundred and twenty-six clones were tested for both proliferative and cytolytic responses; 14 proliferative, noncytotoxic clones and one clone which demonstrated both proliferative and cytotoxic reactivity specific for SB antigens were obtained. The proliferative noncytotoxic clones tested and the clone with both cytotoxic and proliferative activity were all able to produce IL-2-like activity upon specific antigen stimulation in vitro and were positive for OKT3, OKT4 but negative for OKT8. The proliferative clones fit the characteristics of helper T cell (Th) clones while the clone with both cytotoxic and proliferative reactivities is analogous to the class of antigen-driven, helper cell-independent cytotoxic (HITc) clones. No cytolytic nonproliferative SB specific clones were detected. The prevalent induction of Th clones strongly suggests that the biological function of SB antigens is similar to other class II antigens of HLA. The existence of an SB specific HITc clone demonstrates that a determinant on an SB molecule can induce both proliferative and cytolytic responses.

HLA loss variants of a B27+ lymphoblastoid cell line: genetic and cellular characterization

Variants of a lymphoblastoid cell line, LCL 526 (SB3 MB1 DR1 B44 C5 A2/SB4 MT4 DR4 B27 C2 A24), which lost various HLA specificities were selected with monoclonal antibodies and complement using a method developed by Kavathas et al. (PNAS 77:4251, 1980). Using alpha B27 monoclonals, 8 B27 only loss mutants and 4 B27 haplotype multiple loss mutants were generated. The parental LCL 526 and two of the B27- mutants were used to select alpha B27 CTLs. The selection of six A2 loss, one A2-C5 loss, and 14 A2 haplotype multiple loss variants as well as secondary selection on haplotype loss variants to obtain A null, B null, DR null, and total A, B, C, null variants is also described. The usefulness of these mutants for the study of the relationship between B27 and disease and as two new haplotypes for immunologic, genetic, and molecular research is discussed. These mutants are available to other researchers.

A cytolytic human T lymphocyte clone differentially recognizing HLA-B27 subtypes

A cytolytic human T cell (CTL) clone, designated F/M-F159, has been produced, the lytic specificity of which distinguishes subtypes of HLA-B27. This was demonstrated in cell-mediated lympholysis (CML) assays of: 1) a panel of target cells from unrelated donors, 75 B27 + and 36 B27-; 2) six families, including 20 B27 + and 14 B27- individuals; and 3) B27 + and B27- variants of a B27+ lymphoblastoid cell line (LCL). Specificity of F/M-F159 for HLA-B27 was confirmed by blocking studies with monoclonal antibodies. Lysis of B27 + targets reactive with the anti-B27 monoclonal antibody B27M2 was 30-104%, while lysis of B27 +, B27M2- targets was 4-22%. Lysis of B27- targets expressing HLA-Bw47, known to be cross-reactive with the B27M2 antibody, was 10 to 19%, while lysis of all other B27- targets was less than or equal to 10%. Clone F/M-F159 lysed B27 + targets, and failed to lyse B27- targets, irrespective of the clinical status of the cell donors. It is concluded that F/M-F159 recognizes an epitope present on the majority of serologically identified HLA-B27 molecules and that this epitope is closely related to, but not identical with, the epitope recognized by the antibody B27M2. These findings are interpreted as supporting a direct role for HLA-B27 in disease pathogenesis.

Functionally distinct human T cell clones that produce lymphokines with IL-2-like activity

Various functionally distinct human T cell clones derived from in vitro mixed leukocyte cultures are found to secrete lymphokines with detectable Interleukin-2 (IL-2)-like activity upon antigenic stimulation. These lymphokine producing clones are not only dependent on exogenous growth factors provided in the form of crude phytohemagglutinin (PHA)-induced spleen conditioned medium for growth but can themselves be driven to proliferate by their own lymphokines. The induction of lymphokine production appears to be antigen-specific and the lymphokines secreted are believed to contain nonantigen and nonspecies specific IL-2-like activity. We show here that IL-2-like lymphokines are produced by a subset of T lymphocyte clones, i.e., the help-independent cytotoxic T cells clones that have the capacity to proliferate to, as well as to lyse, the original sensitizing cells. In addition, other T cell clones capable of producing active lymphocytes include those clones that have the T helper cell characteristics, i.e., can undergo antigen-induced proliferation but are not cytotoxic; in the presence of lectin (PHA), however, some helper T cells (Th) but not others, can express lectin-dependent cell-mediated lysis. Finally, yet another subset of T lymphocytes, the help-dependent cytotoxic T cell clones that cannot proliferate to antigenic stimulation, was found to produce no detectable IL-2-like activity.

Helper cell-independent cytotoxic clones in man

We report here a class of helper cell-independent cytotoxic T cell (HITc) clones in man that can proliferate in response to antigenic stimulation as well as mediate cytotoxicity. HITc appear to be rare among clones derived from primary in vitro allosensitized culture, but constitute the majority of clones derived from cells sensitized to autologous Epstein-Barr virus-transformed lymphoblastoid cell lines. The implications of the derivation and function of HITc clones are discussed.