Langerhans cell alterations in cutaneous carcinogenesis

Analysis of the early stages of experimental skin cancer in mice has demonstrated that complete chemical carcinogens (e.g. DMBA or benzo(a)pyrene) and tumour promoters (e.g. TPA) but not tumour initiators (e.g. urethane) deplete or functionally alter epidermal Langerhans cells (LC). These changes result in altered local immunity as antigen presentation through LC depleted skin results in either immune tolerance due to the generation of suppressor T cells or anergy. Parallel studies in sheep have shown that, following the application of DMBA, depletion of LC is due to increased migration of these cells from the skin whereas tumour initiators did not alter LC migration. Likewise benzo(a)pyrene did not trigger enhanced LC migration from the epidermis. Experiments in mice suggest that part of this increased migration after the application of DMBA is due to the carcinogen being handled as an antigen by the epidermal LC. However, this fails to explain the prolonged migration which follows. The implication of these studies is that early in carcinogenesis, altered immune function occurs as a result of LC depletion/modification, allowing aberrant cells to proliferate in the absence of immune destruction.

Control of epidemic group A meningococcal disease in Auckland

AIM

To study group A meningococcal vaccine delivery to infants less than 2 years of age in Auckland in 1987 to control epidemic disease.

METHODS

Mechanisms of vaccine delivery and its facilitation are described. A detailed audit of delivery of vaccine to children less than two years using signed consent forms determined delivery source. This was the age group at highest risk, and poorly covered by routine childhood vaccines. Primary health care source of children presenting with disease was determined by telephone.

RESULTS

The epidemic of group A meningococcal disease in the winters of 1985 and 1986 abated most likely due to the vaccination of high risk children (3 months-13 years) in 1987. 90% of the target population were vaccinated. In south Auckland the majority (92%) of vaccine doses for children less than two years of age was delivered by the Plunket Society with Department of Health backing aided by community health workers. By contrast delivery by, general practitioners was greater in north-west and central Auckland (approximately 25%, of dose 1), especially after the publicity over possible side effects (approximately 50% of dose 2). Coverage for dose 1 of children < 2 years was similar (89%) in south Auckland. Of children presenting with meningococcal disease 1 in 4 did not have an identifiable general practitioner.

CONCLUSIONS

Vaccines to prevent serious paediatric illness are known to be highly cost effective. The best method of delivery of vaccinations may vary from area to area. Major community involvement including community health workers for the Maori and Pacific Island communities may have facilitated the dissemination of information in this campaign.

X;6 translocation in a child with congenital acute lymphocytic leukemia

A case of congenital acute lymphoblastic leukemia (ALL) displayed an X;6 translocation. This is the third reported case of ALL with an X;6 translocation. In addition, two of the three ALL cases occurred during infancy, at ages 2 months and newborn, and both translocations involved the band q15-16 region of chromosome 6. Anomalies of the long arm of chromosome 6, mainly interstitial and terminal deletions, have been reported as a recurrent karyotypic event in a significant number of ALL cases. The molecular basis and propensity of an X;6 rearrangement in this case of congenital ALL is unclear and merits further investigation. The similarities in this case and the other infant ALL case cited suggest that an X;6 rearrangement with a breakpoint in bands q15-16 of chromosome 6 is characteristic of a form of congenital ALL.

Identification of a novel latency-specific splice donor signal within the herpes simplex virus type 1 2.0-kilobase latency-associated transcript (LAT): translation inhibition of LAT open reading frames by the intron within the 2.0-kilobase LAT

Herpes simplex virus type 1 establishes latent infection in trigeminal ganglia of mice infected via the eye. A family of three colinear viral transcripts (LATs), 2.0, 1.5, and 1.45 kb, is present in latently infected ganglia. To characterize these LATs, lambda gt10 cDNA libraries were constructed with RNAs isolated from the trigeminal ganglia of latently infected mice. A series of recombinant bacteriophage were isolated containing cDNA inserts covering 1.7 kb of the 2.0-kb LAT. Splice junctions of the smaller LATs and the 3' end of the 2.0-kb LAT were identified by sequence analysis of RNA polymerase chain reaction products. No splice acceptor site, which does not support the hypotheses that the 2.0-kb LAT is an intron. However, the data are consistent with the possibility of a short leader sequence or multiple LAT transcription start sites. To generate the smaller 1.5- and 1.45-kb LATs, there is a 559-nucleotide intron spliced from the 2.0-kb LAT in strain F and a 556-nucleotide intron in strain 17+. The nucleotide sequences at the 5' and 3' ends of these introns are characteristic of spliced transcripts from eukaryotic protein-encoding genes, with one significant difference; i.e., the 5' end of the LAT intron is GC instead of the consensus sequence GT. This splice donor sequence is conserved in herpes simplex virus type 1 strains F, 17+, and KOS. Processing of the 2.0-kb LAT to form the spliced LATs preserves two open reading frames (ORFs) at the 3' end of the LATs; no new ORFs are created. Splicing of the LATs positions a 276-nucleotide leader sequence close to these ORFs and removes an intron that inhibits their translation in vitro. The novel 5' structure of the intron within the 2.0-kb LAT may be part of a control mechanism for transcription processing that results in splicing of the LATs only in sensory neurons during latent infection and reactivation but not during the viral replication cycle.

Clonal loss of INT-2 alleles in sporadic and familial pancreatic endocrine tumours

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Diffuse bony metastases at presentation in a child with glioblastoma multiforme. A case report

At initial diagnosis, an 11-year-old girl with glioblastoma multiforme (GBM) presented with diffuse osteoblastic metastases. Primary brain tumors rarely metastasize outside of the central nervous system (CNS) without prior neurosurgery. Extracranial spread at diagnosis has been previously documented in just two adults. Extracranial metastasis of a childhood glioma without prior neurosurgery at any time during the course of the disease is exceedingly rare. Spread to bone by gliomas is also infrequent, and when they occur, bony metastases are usually isolated to one or two sites in any given patient. The widespread osseous metastases in our patient have been reported in three prior cases of high-grade gliomas. This child's GBM likely reflects a highly aggressive variant with the potential to spread outside the CNS and with a predilection for bone. Oncologists should be aware that GBM may present in this fashion during childhood.

Alpha-streptococcal septicemia in leukemic children treated with continuous or large dosage intermittent cytosine arabinoside

During a 2-year period after the introduction of an intensive chemotherapeutic protocol, alpha-hemolytic streptococci accounted for 75% of all episodes of sepsis among children with acute nonlymphocytic leukemia at our institution. Only one case had occurred in the previous 8 years. Fourteen of 15 episodes of streptococcal sepsis occurred after therapy with either continuous or large dosage intermittent cytosine arabinoside. Eleven episodes occurred at two specific treatment points. Septic episodes were complicated by shock (2 of 15), encephalopathy (2 of 15), pneumonia (3 of 15) and death (1 of 15). Oral mucosal lesions may provide a portal of entry for alpha-hemolytic streptococci. These data suggest that children receiving continuous or large dosage intermittent cytosine arabinoside for treatment of acute nonlymphocytic leukemia may be at increased risk for alpha-hemolytic streptococcal sepsis. Empiric antimicrobial therapy in these children when febrile and neutropenic should include antibiotics effective against alpha-hemolytic streptococci.

Human T lymphocyte colonies require IL2 and are inhibited by anti-Tac

Human T lymphocyte colony formation can be induced in a two-step culture system with phytohaemagglutinin (PHA) as the only exogenous growth factor. In this system the first step is the overnight pre-incubation of mononuclear cells in a liquid medium in the presence of PHA ('activation step'). The second step is the seeding of these PHA-activated cells into semi-solid agar, again in the presence of PHA, and their culture for 7 days ('proliferative step'). We have previously proposed that interleukin 2 (IL2) is produced during the second (proliferative) step and that this IL2 facilitates the production of colonies from PHA-activated colony-forming cells. Here we substantiate this proposal by demonstrating that both highly purified IL2 and recombinant IL2 stimulate T colony formation from PHA-treated cells. The monoclonal antibody anti-Tac, which is specifically directed against the IL2 receptor, dramatically inhibited colony formation when it was included during the agar culture (proliferative step). There was no effect when anti-Tac was included during the liquid pre-incubation culture (activation step). These results provide strong evidence that IL2 is the critical factor in the development of T lymphocyte colonies at the stage of conversion of PHA-activated cells into colonies.

Reversible inhibition of natural killer cell activity by volatile anaesthetic agents in vitro

NK cell cytotoxicity against the erythroleukaemia cell line K562 was studied, during and after the in vitro exposure to clinically-used concentrations of the general anaesthetic agents nitrous oxide, halothane and enflurane. Each of these agents produced a dose-dependent reduction in cytotoxicity. At approximately equipotent doses nitrous oxide produced less suppression than either halothane or enflurane whilst the combination of nitrous oxide with enflurane resulted in an additive suppressive effect. Cytotoxicity was not completely inhibited even by doses up to 12 MAC h. Reversibility of this suppression was demonstrated as cytotoxicity returned to normal within 1 h of the withdrawal of the anaesthetic. Therefore, postoperative immunity, mediated by NK cell cytotoxicity, is unlikely to be significantly depressed following anaesthesia with the agents investigated.

Functional and phenotypic analysis of a T cell prolymphocytic leukemia

Peripheral blood mononuclear cells obtained from a patient with prolymphocytic leukemia expressed the surface membrane markers characteristic of resting mature T helper lymphocytes. These cells responded to the T cell mitogens PHA and Con A in a blast transformation assay but not the anti-T cell monoclonal antibody Leu 4 and the B cell mitogen, PWM. The concentration of PHA or Con A eliciting maximum blast transformation was less than that required by normal mononuclear cells. The leukemic cells recognised and responded to allogeneic pooled mononuclear cells in a mixed lymphocyte culture. In addition, although they did not express Ia antigens, they served as effective stimulators in the mixed lymphocyte reaction. Consistent with the helper phenotype, the leukemic cells did not produce suppressor factors, but provided help for normal B-enriched lymphocytes to respond to PWM as assessed by both blast transformation and IgG production. T lymphocyte colonies developed when the leukemic cells were treated with PHA during a 20 h liquid culture prior to being seeded into semisolid agar medium containing either PHA or an IL2-containing lymphokine. There was no growth when untreated cells were seeded directly into IL2-containing agar. Analysis of colony formation indicated that, as with normal resting T lymphocytes, proliferation occurred in two distinct steps; activation in response to PHA and replication in response to IL2-like growth factors. These findings demonstrate that in this case the helper T prolymphocytes have the functional capabilities of normal mature T lymphocytes as predicted from their helper phenotype.

Cellular interactions and IL2 requirements of PHA-induced human T-lymphocyte colonies

A number of conflicting proposals have been put forward as to the roles and identities of cooperating cells involved with human T-lymphocyte colony formation. To resolve this conflict, the principal cellular interactions of human T-lymphocyte colonies were analyzed using a two-step culture technique. Through mathematical analysis of cell dose-response curves the requirement for at least two populations of cooperating cells in addition to the colony-forming cell was demonstrated. By removing adherent cells prior to the first but not the second step, colony formation was inhibited, which suggests a restricted role for these cells during the early stages of colony formation. The dependence of the second step on interleukin 2 (IL2) availability implied that IL2-producing cells composed the other population of cooperating cells. We therefore propose that colony formation can be described by the two interdependent reactions of activation (T----T') and proliferation (T'----nT'). The first reaction requires an adherent cell (monocyte) population that together with PHA provides the necessary signals for cellular activation. Cell contact is needed to allow the expression of this adherent cell or interleukin 1 ( IL1 ) activity. As a result of these signals at least two subpopulations of lymphocytes are activated, the T-lymphocyte colony-forming cells themselves ( TLCFC ) and a population of cooperating T cells. These activated T cells interact during the second or proliferative reaction. In response to PHA the cooperating T cells release IL2, thereby enabling the activated TLCFs to proliferate into colonies. Thus for PHA-induced T-colony formation, TLCFCs required the cooperation of adherent cells for the activation reaction and IL2-producing T cells for proliferative reaction.

Effects of irradiation on PHA-induced T-lymphocyte colonies: differential effects according to the timing of irradiation

To investigate the effect of irradiation on lymphocyte mitosis we utilized a T-lymphocyte colony assay; this sensitive technique avoided the methodological problems associated with previous techniques such as tritiated thymidine uptake. Irradiation doses in the range of 0.5 to 4 Gy had the effect of decreasing the lymphocytes' capacity to divide as shown by their reduced T-colony-forming ability. This radiosensitivity, however, was found to vary according to the timing of irradiation in relation to the stage of colony growth. Through survival curve analysis it was shown that the colony-forming cells could withstand higher irradiation doses without losing their replicative ability when they were irradiated prior to or during early stages of PHA stimulation. A similar "protection" by PHA stimulation has been well documented for nondividing T-lymphocyte functions but, due to the lack of a suitable methodology, had hitherto not been described for dividing T-lymphocytes. These results provide evidence that the early events associated with PHA stimulation might lead to an improved ability of T-lymphocytes to withstand higher doses of irradiation before mitotic death is registered.

Immunological types of lymphoproliferative disorders in a cohort: a 4-year study

Immunological testing of malignant cells and serum from most cases of lymphoproliferative disorders (LPD) allows the cell type to be characterised as of B, T or "null" lymphocyte origin. Regional differences in the incidence of neoplasms of these types have been reported. Furthermore, most published series have drawn cases from referral institutions rather than the general population. In order to determine the true incidence of a cohort we surveyed an entire population, that of Tasmania, an island state of Australia with a population of 410,000, during a defined period, the years 1977-1980 inclusive, for the occurrence of LPD. A total of 248 cases was discovered, made up of 133 cases of non-Hodgkin's lymphoma (NHL), 30 of chronic lymphocytic leukaemia (CLL), 18 of acute lymphoblastic leukaemia (ALL), 54 of multiple myeloma (MM), eight of macroglobulinaemia (MGA) and five others. We identified B lymphocytes by the presence of surface membrane immunoglobulin (Smlg) and their ability to rosette with mouse red blood cells, and T lymphocytes by their ability to rosette with sheep red blood cells. Laboratory testing was performed in 201 (81%) of the cases and characterisation of the cell of origin as of B, T or "null" type was successful in 158 (64%). Of these 158, 136 (86%) were B, 4 (3%) T, and 18 (11%) "null". On B cell subtyping by heavy and light chain lg analysis the Tasmanian series, compared with other reports, had an apparent paucity of B-CLL, MM and MGA of lambda subtype (57 k to 12 lambda, k:lambda ratio 4.8:1) and an unusual incidence of B-CLL with the double lg heavy chain combination M+G. Surveys of this type may help to point to environmental or other factors important in the aetiology of LPD.

Contact-dependent expression of actin in chicken lymphocytes in vitro

The presence of actin in chicken bursa, thymus and spleen cells has been confirmed using quantitative neutralization absorptions of anti-actin antibody (AAA) with frozen-thawed preparations of these three cell types. Spleen cells were more effective than thymus or bursa cells in reducing the AAA titre. Cell suspensions of these organs were allowed to settle onto a glass slide, air-dried and stained with AAA. Immunofluorescence was restricted to cell borders at points of contact with other cells. This staining was reversibly inhibited by cytochalasin B but not colchicine. The higher content of actin in spleen cells demonstrated by the absorption experiments was reflected in their more rapid expression of actin during smear formation, and the relative resistance of this to cytochalasin B treatment, compared to thymus and bursa preparations. These findings further support the proposition that actin expression is a function of lymphocyte maturation.

Red blood cell requirements of human T lymphocyte colonies

T lymphocytes were induced to form colonies by stimulating mononuclear cells with phytohaemagglutinin (PHA) prior to seeding in agar. The resultant colonies showed heterogeneity in the number of cells per colony and their location of growth, be it within the agar or, less frequently, on top of the agar. Colonies were subdivided according to their size and site of growth. The enhancing effect of sheep red blood cells (SRBC) was investigated through single and double agar experiments. The results indicated that SRBC and red blood cells (RBC) from other sources supported T lymphocyte colony development through a factor or factor(s) that diffused through the agar rather than by direct contact between RBC and the proliferating lymphocytes.

Absence of one component of spectrin adenosine triphosphatase in hereditary spherocytosis

The stimulation by calcium and magnesium of ATPase activity of isolated ghosts, of water-soluble protein (spectrin), and of residual vesicles, derived from normal erythrocytes and from hereditary spherocytes (H.S.), has been measured. The ATPase activity found in normal water-soluble protein (WSP) at low levels of calcium (0.1-2.0 mM) is essentially absent in H.S. water-soluble protein, but the ATPase activity with magnesium and with high levels of calcium (60-100 mM) is the same in H.S. and normal WSP. Compared to normal, H.S. ghosts have increased Mg2+-stimulated activity. This increased activity is retained by the sedimentable vesicles ("residue") after extraction of the ghosts with 0.025 mM EDTA. The Ca2+, Mg2+-ATPase associated with the calcium pump is not significantly different in H.S.

Calcium and magnesium ATPases of the spectrin fraction of human erythrocytes

Using a rapid method of preparation, spectrin has been isolated from human erythrocytes and its ATPase activity investigated. The ATPase activity with calcium has two distinct components, one with optimal activity when calcium and ATP are of equal concentration (low-Ca-ATPase) and another which is activated above 1 mM CaCl2 and is maximal at 100 mM CaCl2. There is also a Mg-ATPase with maximal activity at 10 mM MgCl2. The high-Ca-ATPase of spectrin, but not the low-Ca-ATPase, is inhibited by magnesium, while the Mg-ATPase is inhibited by Ca in excess of ATP. None of these activities exhibits the calcium-stimulated magnesium-dependent activity characteristic of the red cell calcium pump.