Joseph H. Coggin

Identification of HLA-A*0201-Presented T Cell Epitopes Derived from the Oncofetal Antigen-Immature Laminin Receptor Protein in Patients with Hematological Malignancies

The oncofetal Ag immature laminin receptor (OFA-iLR) is a potential target molecule for immunotherapeutic studies in several tumor entities, including hematological malignancies. In the present study, we characterize two HLA-A*0201-presented epitopes eliciting strong OFA-iLR peptide-specific human cytotoxic T cell (CTLs) responses in vitro. Both allogeneic HLA-A*0201-matched and autologous CTLs recognized and killed endogenously OFA-iLR-expressing tumor cell lines and primary malignant cells from patients with hemopoietic malignancies in an MHC-restricted fashion but spared nonmalignant hemopoietic cells. Spontaneous OFA-iLR peptide-specific T cell reactivity was detectable in a significant proportion of leukemia patients. Interestingly, in patients with chronic lymphocytic leukemia and multiple myeloma but not in those with acute myeloid leukemia, significant frequencies of OFA peptide-specific CTLs could be detected in an early stage of disease but disappeared in patients with progressive disease. The identification of OFA-iLR-derived peptide epitopes provides a basis for tumor immunological studies and therapeutic vaccination strategies in patients with OFA-iLR-expressing malignancies.

Tumors express both unique TSTA and crossprotective 44 kDa oncofetal antigen.

Abstract Tumors of inbred rodents and humans generally express a shared tumor-associated transplantation antigen (TATA)-like oncofetal antigen (OFA) and tumor-specific transplantation antigen (TSTA), which stimulate cytotoxic T lymphocyte (CTL) tumor rejection responses. Immunoregulatory CD8 + OFA-specific suppressor T cells are also stimulated, which promote tumor development via interleukin 10 secretion, inhibiting CTL function. Here, Joseph Coggin and colleagues argue that future investigations must distinguish responses to OFA and TSTA.

The implications of embryonic gene expression in neoplasia

The discovery that human as well as animal tumors generally expressed oncofetal antigens (OFAs) and that these antigens generate a variety of immune responses in the tumor-bearing host is of potential major significance in tumor biology. The concept of the reexpression of embryonic or fetal antigens (EAs) encoded by DNA, which is silent in adults but is essential in metazoan development, may mesh with the exciting concept of cancer causation. While this scenario is still only speculative, it provides an interesting forum for reviewing the current data concerning the role of OFAs in cancer processes. The literature describing OFAs and their embryonic counterparts, the EAs, in modern tumor and fetal immunobiology has become extensive and, unfortunately, is quite scattered. This article seeks to synthesize this complicated data base into a cogent presentation focusing on the immunological role of EAs and OFAs in fetal survival in utero and in tumor progression and regression, respectively. The immunogenicity and characteristics of the immune responses to EAs and OFAs will be presented and placed in perspective to the rapidly unraveling story of protooncogenes and oncogenes in tumor induction.

Humoral Immune Responses against the Immature Laminin Receptor Protein Show Prognostic Significance in Patients with Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. The role of an autologous tumor-specific immune control contributing to the variable length of survival in CLL is poorly understood. We investigated whether humoral immunity specific for the CLL-associated Ag oncofetal Ag/immature laminin receptor (OFA/iLR) has a prognostic value in CLL. Among sera of 67 untreated patients with CLL, 23 (34.3%) had detectable OFA/iLR Abs that were reactive for at least one specific OFA/iLR epitope. Patients with humoral responses compared with patients with nonreactive sera had a longer progression-free survival (p = 0.029). IgG subclass analyses showed a predominant IgG1 and IgG3 response. OFA/iLR Abs were capable of recognizing and selectively killing OFA/iLR-expressing CLL cells in complement-mediated and Ab-dependent cellular cytotoxi cityassays. In the analysis of 11 CLL patients after allogeneic hematopoetic stem cell transplantation, 8 showed high values for OFA/iLR Abs that specifically recognized the extracellular domain of the protein, suggesting a potential role of anti-OFA/iLR-directed immune responses to the graft-vs-leukemia effect in CLL. Our data suggest that spontaneous tumor-specific humoral immune responses against OFA/iLR exist in a significant proportion of CLL patients and that superior progression-free survival in those patients could reflect autologous immune control.

Human squamous cell carcinoma lines express oncofetal 44‐kd polypeptide defined by monoclonal antibody to mouse fetus

Most primary human carcinomas uniformly express an oncofetal epitope which has not been demonstrated previously in established human carcinoma cell lines. We successfully derived several low‐passage cell lines of human squamous cell carcinoma (SCC) from head and neck tumors using an in vitro adaptation procedure, characterized these lines, and examined them for expression of a 44‐kilodalton (kD) polypeptide (PP) oncofetal antigen (OFA) at the cell surface. Newly established and in vitro‐passaged SCC cells retained characteristic microvilli, numerous desmosomes and tonofilaments, abundant rough endoplasmic reticulum, osmophilic keratohyaline granules, and other features of the primary SCC cells. These new cell lines and two long‐term, established SCC lines (FaDu and Detroit 562) displayed OFA at the cell surface, as determined by flow cytometry using monoclonal antibody (MoAb) 115. While the FaDu and Detroit 562 lines exhibited aneuploidy during flow cytometric analysis, the new, low‐passage SCC lines that we developed remained diploid as were the primary SCC cells from which they were derived. We propose that the expression of a 44‐kD OFA is a common feature of human SCC. This marker may prove useful in the detection and treatment of these tumors.

Identification of Oncofetal Antigen/Immature Laminin Receptor Protein Epitopes That Activate BALB/c Mouse OFA/iLRP-Specific Effector and Regulatory T Cell Clones

During tumor development in mice and humans, oncofetal Ag/immature laminin receptor (OFA/iLRP)-specific Th1, CTL, and IL-10-secreting T (Ts) cells are induced. The presence of too many Ts or too few effector T cells appears to predict a poor prognosis. We established clones of OFA/iLRP-specific splenic Th1, CTL, and Ts cells from the OFA/iLRP+ MCA1315 fibrosarcoma-bearing BALB/c mice or from BALB/c mice vaccinated with 1 or 10 μg of rOFA/iLRP. The MCA1315 tumor cell-reactive T cell clones were characterized as to surface Ag phenotype, cytokine secretion profile, and specificity for OFA/iLRP presented by syngeneic splenic APC. OFA/iLRP-specific Th1 and Ts clones were established from all mice. OFA/iLRP-specific CTL could be established from all mice except for mice immunized with 10 μg of rOFA/iLRP. Analysis of the proliferation profile of the OFA/iLRP-specific clones to overlapping OFA/iLRP 12-mer peptides that spanned the OFA/iLRP protein sequence defined the epitopes to which the T cell clones responded. There was a similar spatial distribution of the epitopes to which the two types of CD8 T cell clones responded. The nonapeptide epitopes of the Ts clones were located between aa 36 and 147 of OFA/iLRP, while the epitopes of the CTL clones were located between aa 52 and 163. Even though the CTL and Ts epitopes shared part of the protein, all of the CD8 CTL epitopes were distinct and separable from those of CD8 Ts cells.

High expression of the immature laminin receptor protein correlates with mutated IGVH status and predicts a favorable prognosis in chronic lymphocytic leukemia

The immature laminin receptor (iLR) is a tumor-associated antigen. We analyzed the expression of iLR on malignant B cells of 134 unselected patient samples with CLL and hypothesized that iLR expression would have prognostic significance due to a differential expression pattern. High ILR expression (cut-off value 30%) was correlated with mutated IGVH status (p<0.0001). Patients with high iLR-expression had a significantly longer time to progression (p=0.039). Combination of CD38, ZAP-70, and iLR by flow cytometry can be used to construct a diagnostic score identifying patients with a median progression free survival of 80 months, if no adverse marker is present.