Catherine Barras

Evidence for HLA-linked susceptibility factors in childhood leukemia

To test the hypothesis that susceptibility to leukemia can be governed by (a) recessive gene(s) associated with the major histocompatibility complex (MHC) in man, we performed an analysis of the inheritance of HLA antigens in 55 families in which one of the children developed ALL. We found among the parents of affected children a highly significant increased compatibility at the DR locus (p = 0.003). A similar increase was observed in sharing HLA antigens of the B locus (p = 0.02). The observed number of homozygotes among the patients was twice the expected value in families where the parents shared a B and a DR antigen. In segregation analysis, heterozygotes for the shared parental HLA antigen were significantly more prevalent among the healthy siblings. Our genetical analysis indicates that mating of certain shared alleles of the HLA system (especially of the DR locus) is associated with the risk for the offspring to develop ALL in childhood. This situation favors the expression of recessive genes associated with the MHC, and presumably those involved in the susceptibility to acute leukemia. Because familial leukemia is a rare event, the susceptibility to childhood ALL must also implicate genes outside the MHC and important environmental factors.

Sparse distribution of γ/δ T lymphocytes around human epithelial tumors predominantly infiltrated by primed/memory T cells

SummaryEvidence from the mouse system has suggested that T lymphocytes accumulating in non-lymphoid tissue, in particular epithelia, may preferentially express the T cell receptor (TCR) γδ. In this study, we characterize the T cell receptor αβ or γδ phenotype of lymphocytes infiltrating human tumors of epithelial origin using monoclonal antibodies (mAb) for immunohistology and flow cytometry on cells extracted by enzyme digestion. This report shows that the majority of CD3+ tumor-infiltrating lymphocytes are TCR αβ+ but a small percentage of TCR γδ can be clearly defined scattered throughout the tumor tissue with apparently no microanatomical selection. So far there has been little evidence for an accumulation of activated T cells in human tumor tissues as defined by mAb against molecules appearing transiently during the acute phase of activation. Now mAb are available that can identify primed or memory T cells such as mAb UCHL-1 recognizing the CD45RO antigen. Here we show that CD3+ tumor-infiltrating lymphocytes have a statistically significant accumulation of primed T cells, as compared to the autologous peripheral blood lymphocytes, suggesting their immune stimulation by tumor cells.

Production of tumor necrosis factor-α by naive or memory T lymphocytes activated via CD28

Abstract While it is well established that activated T cells can produce tumor necrosis factor alpha (TNF-α), it is less clear whether this function is confined to a given subset, e.g., memory cells. To approach this question, we investigated the production of TNF-α by human peripheral blood T lymphocytes activated with anti-CD28 mAb since this activation pathway is known to potentiate cytokine production. Under the culture conditions used, the amount of TNF-α produced was markedly enhanced compared to that obtained after activation with immobilized anti-CD3 mAb. The enhancement of TNF-α production was already apparent after incubation of T cells for 6 hr. Up to 5 ng/ml of TNF-α was measured on Day 2 in supernatants of cultures of 104 T lymphocytes. To determine the source of the cells producing high amounts of TNF-α, T lymphocytes were separated into two subpopulations, namely naive cells (expressing the CD45RA isoform) and memory cells (expressing the CD45RO isoform). While both subpopulations proliferated equally well after stimulation with anti-CD28 mAb, up to 90% of the TNF-α produced under these conditions originated from memory T cells. These results thus document that T cell activation via CD28 results in a marked increase in TNF-α production without affecting the functional disparity that exists between naive and memory T cells.

Stimulation of FACS-analysed CD4+ and CD8+ human tumour-infiltrating lymphocytes with ionomycin + phorbol-12,13-dibutyrate does not overcome their proliferative deficit.

Human tumour‐infiltrating lymphocytes (TIL) were prepared by enzyme digestion from a series of different tumours and were purified on a fluorescence‐activated cell sorter (FACS II) according to their CD4+ and CD8+ phenotype. CD4+ and CD8+ TIL were stimulated separately in a low density microculture system with phytohacmagglutinin (PHA) or with ionomycin plus phorbol‐12, 13‐dibutyrate (PDBu). The PHA‐induced proliferation of TIL was highly decreased when compared with control peripheral blood lymphocytes. A decreased proliferation of TIL was also observed when cells were stimulated with ionomycin plus PDBu, a combination which is thought to circumvent early events associated with lymphocyte activation. Some TIL were also plated in limiting dilution where they showed decreased frequencies of proliferating T cell precursors. The data suggest that one component of the inhibition of TIL must be acting ‘ownstream’ of the early events of lymphocyte activation.

Heterogeneity of Ia antigen expression on myeloblastic leukaemias: correlation with stage of maturation defined by cytochemical markers

Summary The expression of Ia‐like antigen (la) has been studied in 55 cases of acute myeloid leukaemia (AML) in correlation with the expression of both Sudan Black (SB) and naphthol AS‐D chloroacetate esterase (NCAE) stains. Operationally the AML cases were divided into three groups using only NCAE expression on the leukaemic cells: the first group with early maturation stage (MS1) consisted of 30 cases with less than 10% NCAE positive cells (SB: 15–100%); the MS2 group of 14 cases with 10–70% NCAE positive cells (SB: 65–100%) and the MS3 group of 11 cases with 70–100% NCAE positive cells (SB: 89–100%).

Cytotoxic Tumor Infiltrating Lymphocytes in Nasopharyngeal Carcinoma

Tumor Infiltrating Lymphocytes (TIL) are particularly abundant in nasopharyngeal carcinoma (NPC) and participate into the “lympho-epithelial” histological pattern characteristic of this tumor. The malignant cells are of epithelial origin and it has been shown recently (1,2) that NPC tumors in nude mice constitutively express class II Major Histocompatibility Complex (MHC) antigens and produce Interleukine-1 (IL-1), a lymphokine which plays an important role in T cell migration and activation. The expression of such immuno-regulatory molecules by the malignant epithelial cells may play a key role in the striking lymphocytic infiltrate of NPC (T. TURSZ et al., this volume). The TIL are not malignant, do not contain EBV genomes and their majority belongs to the T cell lineage as shown by immunohistological studies (3,4).