Ailsa M. Campbell

Multispecific monoclonal antibodies

Monoclonal antibodies are frequently shown to participate in unexpected cross reactions involving two apparently dissimilar antigens. This can be attributed either to partial epitope identity or to irrelevant interactions involving additional binding capacity of the antibody. The majority of such interactions appear to fall into the latter category. Such cross reactions are most commonly detected when one of the antigens has a high epitope density and the antibody is multivalent so that a spurious interaction of low intrinsic affinity is amplified by local concentration effects. In this review Souravi Ghosh and Ailsa Campbell discuss the selection of a monoclonal antibody for maximum affinity for the antigens it is designed to study and minimum cross-reactivity.

Flow cytometric analysis of tumour infiltrating lymphocytes in breast cancer.

In 31 patients with carcinoma of the breast the phenotype and activation status of tumour infiltrating lymphocytes (TILs) was analysed by flow cytometry. The predominant cells, in all patients, were T lymphocytes and in the majority of cases CD8+ (cytotoxic/suppressor) T lymphocytes were present in greater numbers than CD4+ (helper) T lymphocytes. There was no relationship between the degree of lymphocytic infiltration and either tumour stage or grade but there appeared to be an inverse correlation with the levels of oestrogen receptor (ER) in the tumour (P less than 0.01). Both populations of T cells had significantly higher numbers of cells carrying HLA DR (class II major histocompatibility antigen) than the equivalent populations in peripheral blood from the same patient group (P less than 0.001). The transferrin receptor was found on similar numbers of CD8+ T cells in peripheral blood and among the tumour infiltrating lymphocytes while more of the CD4+ T cells infiltrating the tumour were found to carry this receptor (P = 0.034). The Tac (CD 25) antigen was also on similar numbers of CD8+ T cells from both peripheral blood and the tumour but was on fewer of the CD4+ T cells in the tumour with respect to peripheral blood (P = 0.029). In both TILs and blood lymphocytes, the Tac antigen was consistently present on greater numbers of CD4+ T lymphocytes than on the CD8+ T lymphocytes (P less than 0.001) and as this is a component of the interleukin 2 (IL-2) receptor this may be of relevance to the use of IL-2 in TIL cancer therapy.

The effects of perindopril on vascular smooth muscle polyploidy in stroke-prone spontaneously hypertensive rats

Objective To quantify vascular smooth muscle polyploidy and growth kinetics in aortic cells from stroke-prone spontaneously hypertensive rats (SHRSP) and from normotensive Wistar-Kyoto (WKY) rats, and to examine the effects of treatment with the angiotensin converting enzyme (ACE) inhibitor perindopril on these parameters. Design The following experimental groups were used: young (age <20 weeks) and old (age > 20 weeks) untreated WKY rats and untreated SHRSP; SHRSP treated with perindopril, and age- and sex-matched control SHRSP; and SHRSP treated with hydralazine and hydrochlorothiazide and age- and sex-matched control SHRSP. The effects of treatment of the SHRSP with perindopril for 30 days on vascular smooth muscle polyploidy and growth kinetics were measured and compared with the effects of equivalent antihypertensive doses of hydralazine and hydrochlorothiazide. Methods Vascular smooth muscle polyploidy was measured using flow-cytometry DNA analysis of freshly harvested cells. Growth curves were performed on cultured aortic cells. Plasma renin activity was measured by an antibody-trapping method, plasma angiotensin II (Ang II) by radioimmunoassay and plasma ACE activity by a colorimetric method. Cardiac hypertrophy was evaluated by measuring the heart weight: body weight and left ventricle + septum weight: body weight ratios. Results The SHRSP had markedly and significantly elevated G2 + M phase of the cell cycle. Treatment with perindopril resulted in a significant reduction in polyploidy in the SHRSP, whereas treatment with hydralazine and hydrochlorothiazide had no effect on the percentage of cells in the G2 + M phase of the cell cycle. The regression of polyploidy after treatment with perindopril was associated with a significant reduction in the concentration of Ang II and ACE activity, and with a significant regression of cardiac hypertrophy. Increased mitogenesis of cultured vascular smooth muscle cells from the SHRSP was not altered by treatment with perindopril. Conclusions ACE inhibition reduces vascular smooth muscle polyploidy in large conduit arteries. This type of vascular protection is mediated by the reduced Ang II and possibly by increased kinins level, rather than by the hypotensive effect alone.

Flow cytometric analysis of cell surface carbohydrates in metastatic human breast cancer

Helix pomatia agglutinin (HPA)- and Concanavalin A (Con A)-binding carbohydrate expression were studied on 32 tumour samples from primary adenocarcinoma of the breast and 12 samples from lymph node metastases. Live cells were spilled from each of the fresh samples and the extent of fluorescent-labelled HPA and Con A-binding was assessed by flow cytometry. The extent of brightness was expressed in a defined quantitative fashion and the percentage of positive cells was accurately determined from a sample of 10,000 cells per tumour. Correlation of binding with clinicopathological features showed that HPA but not Con A related to lymph node involvement (P = 0.001) in tumours of higher grade (II and III). Spilled tumour cells (non-lymphocytes) were selected from the lymph nodes and the presence of HPA binding cells in the involved lymph nodes was found to relate to positive HPA binding in autologous primary tumours (P = 0.002). Dual-label analysis of HPA and Con A binding showed characteristic features for each tumour. The study demonstrates the use of flow cytometry as a simple and effective technique in detecting differences in lectin binding in live spilled cells from fresh breast cancer tissues. This method may prove to be particularly useful if performed preoperatively on cells in fine-needle aspirates.

T cell receptor gamma/delta expression on lymphocyte populations of breast cancer patients

The quantitative distribution and phenotype of gamma/delta lymphocytes in the peripheral blood (PBL), tumour draining lymph node (LNL) and tumour infiltrating lymphocytes (TIL) from breast carcinoma patients were determined by one- and two-colour flow cytometry. The TCR-gamma/delta + cells generally expressed the T cell lineage antigen CD3. The proportions of such cells were variable but generally small from all the three sources. Phenotypic analysis revealed that the CD8 marker was consistently and predominantly observed on gamma/delta + CD3+ cells in the tumour infiltrate, whereas CD4 expression, while generally low, was noted on a significant percentage (median 10%) of LNL gamma/delta + lymphocytes. In both PBL and LNL the predominant gamma/delta cell population was CD4-8-.

The molecular weight of nucleosome protein by laser light scattering

The present experimental evidence on the structure of the nucleosome suggests that a ‘core’ containing two of each of the histone molecules H2A, H2B, H3 and H4 is surrounded by 180 to 200 base pairs of DNA [l-3] . It has been claimed from cross-linking evidence that in 2 M NaCl, at pH 9.0, an octameric nuclear core can be isolated in the absence of DNA from rat liver chromatin [4]. However, examination by hydrodynamic and formaldehyde cross-linking techniques [ 51 of the histone core from chicken erythrocyte chromatin, extracted by similar procedures but at pH 7.4, suggest it is isolated as two heterotypic tetramers of the four histones. Light scattering is an exceptionally suitable technique for resolution of this type of discrepancy between different forms of experimental data. It yields an absolute, weight average molecular weight over a wide concentration range, and with the availability of laser light sources and modern filtration techniques, it can be employed on small amounts of material with no dust contamination. Consequently it has been used to resolve problems relating to the conformations adopted by multi-subunit proteins, particularly in solutions of high ionic strength where small molecule binding can complicate the measurement of other molecular parameters [6]. The experimental work described in this paper was undertaken to obtain a correct molecular weight

Altered lymphocyte populations in tumour invaded nodes of breast cancer patients.

Lymphocytes from matched pairs of tumour-invaded and tumour-free lymph nodes from 22 stage II breast cancer patients have been analysed for expression of phenotypic and activation markers by flow cytometry. Although the relative proportions of T and B lymphocytes were similar in the two nodes, significant differences in the distribution of T cell subsets were observed between nodes that were invaded and those that were not. The CD4/CD8 ratio was markedly depressed in tumour invaded nodes (P < 0.001). This was due to an increase in the number of CD8+ T cells (P < 0.001) and a decrease in the CD4+ T cell population (P = 0.008) in invaded nodes in comparison with tumour-free nodes. The percentage of CD8+ T cells expressing HLA DR (P = 0.023) and IL-2 receptors (Tac) (P = 0.029) was significantly higher in invaded nodes and, while CD4+ T cells expressing HLA DR (P = 0.036) were also in a higher proportion of Tac expressing CD4+ T cells failed to reach significance. Although invaded nodes in a few patients were found to have a higher percentage of IgG-expressing B cells, no significant differences were observed between the two groups of nodes. These results suggest that the presence of metastatic tumour cells in a lymph node is associated with specific alterations in the T cell population.

A monoclonal antibody specific for the A antigen of Brucella spp.

Two murine monoclonal antibodies of the IgG3 class have been isolated after immunization with Brucella abortus. An indirect immunofluorescence test was used to screen hybridoma supernatants and subsequently to determine the cross-reactivity of the monoclonal antibodies with other bacteria. One monoclonal antibody reacted with all the smooth Brucella biotypes tried and with Yersinia enterocolitica serogroup 0:9, though not with rough Br. ovis or with strains of Escherichia, Proteus, Salmonella, Pseudomonas, Francisella and Bordetella. The other monoclonal antibody displayed a high degree of specificity for brucellae carrying the A lipopolysaccharide-protein surface antigen. The implications for the diagnosis of brucellosis are discussed.

Flow cytometric analysis of tumour-draining lymph nodes in breast cancer patients

The phenotype and activation status of lymphocytes from the peripheral blood and axillary lymph nodes of 40 patients with breast cancer were analysed using flow cytometry and compared with lymphocytes from the blood and lymph nodes of 7 control subjects. There was little difference in the overall proportions of T and B lymphocytes but there was a much larger population of B cells bearing surface IgG and a greater number of CD4+ helper T cells, particularly in the regional nodes, in the breast cancer patients. Many more T cells in the cancer patients were found to be carrying the HLA DR and Tac antigens. The axillary lymph nodes were the major site of B cells and CD4+ T cells whilst the primary tumour was the source of the CD8+ suppressor/cytotoxic T cells. Any immune response appeared to be largely loco-regional and may therefore destroyed by conventional surgery or radiotherapy.

Electron immunocytochemical localization of retinal S-antigen with a rat monoclonal antibody**

This report describes the ultrastructural localization of S-antigen in pig and human retinas by means of a highly specific rat IgG monoclonal antibody, S2.4.C5, followed by a secondary antibody adsorbed to colloidal gold. This monoclonal antibody gave definitive staining with negligible background. The protein was detected in both the rod outer and inner segments. Connecting cilia and the rod outer segment disc membranes were labelled. The outer segment plasma membrane was not obviously labelled. Cones were labelled at background level. S-Antigen was not detected in any other cells of the neural retina. The fate of S-antigen was also followed to the pigment epithelial phagosomes where intracytoplasmic ROS debris was stained with the antibody. No label, however, was detected in the choroid, suggesting that trans-cellular transport of the S-antigen did not occur.