Methods for the establishment of continuously growing cytolytic T cell clones

T cell response to embryonal carcinoma F9 cells: induction and characterization of T cell receptor alpha beta+ double-negative cytotoxic T lymphocytes

We investigated the mechanism of T cell response to murine embryonal carcinoma F9 cells. Thy-1+, CD4-, CD8- (double-negative) cytotoxic effector cells were induced in spleen cells obtained from immune A.BY mice to F9 cells, and the cytotoxic activity was major histocompatibility complex (MHC)-unrestricted. Furthermore, CD4+ T cells were essential for the induction of double-negative cytotoxic T lymphocytes directed to F9 cells. Most of the double-negative cytotoxic T lymphocyte lines obtained by long-term culture of the effector cells had CD3 molecule and T-cell receptor beta chain on their cell surface, and the CD3 molecule was found to be involved in target cell recognition. The T cell receptor alpha beta+ double-negative cytotoxic T lymphocyte line (2A5) also lysed various tumor cells in a non-MHC-restricted manner, but did not lyse concanavalin A-stimulated blasts of 129 strain, from which F9 cells had originated. These results indicate that T cell receptor alpha beta+ double-negative cytotoxic T lymphocytes induced by F9 cells recognize a common antigen(s) expressed on F9 cells and other tumor cells but not minor histocompatibility antigens.

Augmentation of human cytotoxic T lymphocytes against autologous tumor by a factor released from human monocytic leukemia cell line

A human acute monocytic leukemia cell line, THP-1, releases a factor which activates human cytotoxic (killer) T lymphocytes (CTL) against autologous tumor in vitro. The factor, named cytotoxic (killer) T cell activating factor (KAF), is an acidic protein of 70,000 to 100,000 dalton molecular size. Peripheral blood leukocytes from two patients, bearing epithelioid sarcoma or malignant schwannoma, were cultured for 7 days with individual autologous tumor to induce CTL directed to the corresponding tumor. Monocyte-depleted peripheral leukocytes generated lesser CTL activity than the monocyte-containing leukocyte population. However, the KAF was able to replace the monocyte function. The KAF acted at the CTL generation phase as well as the effector phase. The KAF-activated killer cells possessed CD4-8+ surface phenotype. The CTL killed autologous tumor or other unrelated tumor cell lines only when they shared some of the HLA class I antigens. It was also demonstrated that the KAF does not activate killer cells without proper antigenic stimuli, because the KAF-augmented CTL possess specificity against autologous tumor or other HLA-A or -B matched tumor cell lines. The therapeutic applicability of human KAF for anti-tumor CTL therapy against autologous tumor is discussed.

Stable expression of clonal specificity in murine cytomegalovirus-specific large granular lymphoblast lines propagated long-term in recombinant interleukin 2

The somatic stability of cloned long-term cytolytic T lymphocyte lines (CTLL) specific for antigens encoded by murine cytomegalovirus (MCMV) was tracked for more than two years of continuous in vitro propagation. Clone S1 retained its original specificity for a structural (S) antigen of MCMV for about eight months in the presence of antigen and interleukin 2 (IL 2), but not in IL 2 alone. In the following months, however, in spite of the continued presence of antigen, clonal variants developed that displayed distinct patterns of target cell recognition, including loss of the original specificity and acquisition of exclusive specificity for the natural killer target cell YAC-1. On the other hand, large granular lymphoblast (LGL) lines, line IE1-IL and a series of sublines thereof, could be established that stably expressed Ld-restricted specificity for a viral nonstructural immediate-early (IE) antigen more than two years after withdrawal of antigen and feeder cells when propagated in the presence of pure recombinant human IL 2. The finding that the presence of antigen was not essential for the stability of clone IE1-derived CTLL indicates that maintenance of specificity in LGL lines is not a result of antigen-mediated selection, but reflects an intrinsic property.

Cytotoxic T lymphocyte clone recognizing self idiotype: its regulatory role in antibody production

MOPC 104E idiotype-specific cytotoxic T lymphocyte (CTL) clones were established. The clone KA1.02 specifically killed MOPC 104E cells and inhibited anti-dextran antibody production in an idiotype-specific manner. Both cytotoxicity and antibody inhibition were restricted to the cross-reactive idiotype and class I histocompatibility antigen. The data presented here provide definitive evidence that the self idiotype is the immunogenic determinant recognized by T lymphocytes in association with the major histocompatibility complex product. A regulatory role of CTL in antibody response is proposed.

Different functional subsets of cultured murine T cells express characteristic levels of adenosine deaminase activity

The level of adenosine deaminase (ADA) activity in mouse T-lymphocyte cultures was studied under different growth-supporting conditions and in mixed lymphocyte culture-derived long-term T-cell lines and clones. Early after the initiation of in vitro culture, the levels of ADA (2000 U/mg) were similar in bulk cultures either depleted or not depleted in Lyt-2+ T cells. Enrichment for cytolytic T lymphocytes (CTL) obtained by addition of exogenous interleukin 2 (IL-2), was accompanied by a net decrease of ADA activity (110 +/- 15 U/mg). All the tested CTL-A lines derived from such cultures were also characterized by a low or undetectable level of this enzyme (at best 160 +/- 70 U/mg) as previously observed. In contrast, "Lyt-2-" T-cell bulk cultures grown, without addition of exogenous IL-2, in the presence of gamma-irradiated H-2d stimulators maintained a constant level of ADA activity (1770 +/- 340 U/mg) for at least 3 months. Functionally distinct types of Lyt-2- T-cell lines were also analyzed: T-cell lines competent to activate B lymphocytes to growth and terminal maturation as well as others devoid of detectable functions showed a stable ADA level comparable to that expressed by the original bulk culture 1685 +/- 620 U/mg). The present results demonstrate that, like tumor cell lines, most normal T lymphocytes express a high level of ADA activity in culture, which strongly suggests that the low level of ADA activity exhibited by CTL is a characteristic of this functional subset.

Posttranslational modification of human T-cell growth factor

Amino-terminal sequence analysis of human T-cell growth factor indicated that the amino acid in position 3 of the polypeptide chain was modified. Examination of the N-terminal octapeptide using the amino acid analyzer and mass spectrometry demonstrated that position 3 was a threonine which was linked to N-acetyl-D-galactosamine. This site of glycosylation is of practical significance since it appears to play a role in the selectivity of a monoclonal antibody for the factor.

Diversity in the biological properties of anti-influenza cytotoxic T cell clones

This study reports the examination of in vivo and in vitro properties of an antigen-dependent murine cytotoxic T cell (Tc) clone T5/5 specific for type A influenza virus. This clone differs morphologically and in its migratory pattern and biological properties from a previously examined anti-influenza Tc clone L4 which grew in T cell growth factor independently of antigen. Unlike Tc clone L4, T5/5 cells do not release significant amounts of immune interferon on contact with influenza-infected target cells nor do they limit virus replication in vivo, although they efficiently lyse influenza-infected target cells and can release interferon in the presence of concanavalin A. Thus individual Tc clones vary in function and further work is required to establish the properties of Tc that are associated with host protection against virus infection.

Simple immunization protocol for high frequency production of soluble antigen-specific hybridomas

We report the immunization protocol used to produce high frequency of specific hybridomas secreting defined antibodies against soluble proteins. The two immunization schemes used consist in 1300 and 115 micrograms of protein distributed over a period of two weeks. The specific efficiency (SE) of positive clones recovered in eleven different fusion experiments ranged between 0.52 and 0.78. These values are referred to hybridomas secreting monoclonal antibodies (MAbs) against soluble proteins such as human chorionic somatomammotropin (hCS), human growth hormone (hGH), and human prostatic acid phosphatase (hPAP). Similar high SE were also recovered by immunizing mice with nonsoluble antigens such as intermediate filaments of cytoskeleton (IF).