James L. Urban

Restricted use of T cell receptor V genes in murine autoimmune encephalomyelitis raises possibilities for antibody therapy

Experimental allergic encephalomyelitis (EAE) is a paralytic autoimmune disease induced in susceptible animals by active immunization with myelin basic protein (MBP) or by passive transfer of MBP-specific T helper (TH) lymphocytes. We have analyzed the T cell receptor genes of 33 clonally distinct TH cells specific for a nonapeptide of MBP inducing EAE in B10.PL (H-2u) mice. All 33 TH cells used two alpha variable gene segments (V alpha 2.3, 61%; V alpha 4.2, 39%), the same alpha joining gene segment (J alpha 39), and two V beta and J beta gene segments (V beta 8.2-J beta 2.6, 79%; V beta 13-J beta 2.2, 21%). The anti-V beta 8 monoclonal antibody F23.1 was found to block completely recognition of the nonapeptide by V beta 8 TH cells in vitro and to reduce significantly the susceptibility of B10.PL mice to peptide-induced EAE.

Encephalitogenic T cells in the B10.PL model of experimental allergic encephalomyelitis (EAE) are of the Th-1 lymphokine subtype

T helper cells reactive to myelin basic protein are clearly implicated in the pathogenesis of murine EAE. We have developed a T cell line, BML-1 that (1) is reactive to the encephalitogenic amino terminal nonapeptide (1-9NAC) of MBP, (2) is I-Au restricted, and (3) induces relapsing EAE in B10.PL (H-2u) mice. Measurement of the lymphokine profile of BML-1 revealed secretion of IL-2, interferon-gamma and lymphotoxin but not IL-4. This profile is consistent with the Th1/DTH subtype. Coculture of BML-1 with MBP-primed B cells shows that BML-1 does not provide significant helper function in vitro. In addition, BML-1 secretion of interferon-gamma was found to inhibit LPS-induced anti-MBP antibody responses. This suggested that anti-MBP antibodies may not be necessary for induction of EAE. Sera from mice, in which severe disease was induced with the 1-9NAC peptide and Bordetella pertussis, showed no development of serum antibodies to MBP. These data show that MBP-reactive Th cells of the Th-1/DTH subtype can induce EAE and do not provide Th function for anti-MBP responses and that serum anti-MBP antibodies are not found in peptide 1-9NAC-induced disease. T cell lines specific for encephalitogenic epitopes and characterized for lymphokine secretion will provide a useful tool for understanding the role of T cells in the induction of EAE.

Autoimmune T cells: Immune recognition of normal and variant peptide epitopes and peptide-based therapy

Experimental autoimmune encephalomyelitis (EAE) results from T helper (TH) cell recognition of myelin basic protein (MBP). We have characterized TH cell reactivity in B10.PL and PL/J (H-2u) mice to 39 N-terminal MBP peptide derivatives of different lengths and with individual amino acid substitutions. The peptide determinant of murine MBP can be divided into a minimal stimulatory core region (residues 1-6) and a tail region (residues 7-20) that alters the structure of the core region to affect both T cell recognition and MHC binding. Core recognition by B10.PL and PL/J mice is highly similar but in one case strain dependent. Peptide analogs that do not stimulate MBP-specific TH cells but bind to the I-Au molecule competitively inhibit T cell reactivity to MBP in vitro and prevent the induction of EAE in vivo.

Surveillance Role of Various Leukocytes in Preventing the Outgrowth of Potentially Malignant Cells

Several different types of leukocytes can destroy cancer cells in vitro (Klein et al., 1960; Hibbs et al., 1972; Herberman et al., 1975; Kiessling et al., 1975). Rather little, however, is known about the relative importance of these different leukocytes in the normal host, where they may exert a surveillance function and prevent the outgrowth of potentially malignant cells. We have studied the relative efficiency of the different leukocytes in restraining malignant growth in vivo by comparing the effects of the leukocytes on regressor tumors and on progressively growing tumor variants that have escaped the immunity of the host. This type of approach is based on the premise that if a leukocyte operates effectively in vivo in restraining the growth of a tumor, a tumor cell must become resistant to it before it can grow progressively. A study of such phenotypic changes in tumor variants should therefore give insight into the relative importance and hierarchy of the different naturally occurring immune defense cells. This type of analysis is analogous to that performed by the microbiologist who deduces the mechanism of action of an antibiotic from the type of change found in a bacterium that has become resistant to the drug.

INTERRELATIONSHIP BETWEEN NK ACTIVITY AND T CELL-MEDIATED IMMUNITY IN SYNGENEIC TUMOR REJECTION

Publisher Summary This chapter examines interrelationship between natural killer (NK) activity and T-cell-mediated immunity in syngeneic tumor rejection. The study described in the chapter used direct isolation of effector cells from the site of injection of viable tumor cells, that is, the peritoneal cavity. With this direct analysis, the in vivo relevance of the study seemed to be less questionable because none of the effector cells had to be subjected to any long-term culturing in vitro prior to testing. Thus, mice were injected with 1591 parental regressor tumor cells or with a subtumorigenic dose of 1591 progressor variant tumor cells and 8 days later effector cells were removed from the peritoneal cavities of these animals and tested for cytolytic activity. Animals injected with the parental 1591 tumor cells developed Lyt-2 + T cells which lysed the 1591 tumor cells. Neither the antigenically distinct UV-induced 1316 tumor cells nor seven independently isolated 1591 progressor variant cells lines were lysed. It was shown that Lyt-2 + tumor-specific reactivity could not be elicited by the injection of progressor variant tumor cells. Injection of progressor variant cells induced high levels of some other type of Lyt-2 − cytolytic effector cell.