Abstract P1-13-08: Chemotherapy for Breast Cancer Causes Sustained Alteration In Number and Type of B Lymphocytes

Introduction: The initial immune toxicities of chemotherapy have been reported but longer-term effects are less clear. In order to ascertain if patients regain immuno-competence after chemotherapy, we studied the time-course and determinants of changes in lymphocytes during and after breast cancer chemotherapy, and the characteristics of repopulating cells.

Methods: To determine the long-term effects of chemotherapy on adaptive immunity, detailed immunophenotyping was performed on primary breast cancer patients before and after chemotherapy. Blood samples were collected from 83 patients prior to and at various time points post-chemotherapy. Total B and T lymphocyte number and B cell subpopulations were assessed by flow cytometry. Data was analysed using Wilcoxan Signed Rank Test, Mann Whitney U test or Kruskal-Wallis test (SPSS).

Results: Chemotherapy resulted in significant reduction in numbers of circulating CD3+ cells (median 42.7% of pre-chemotherapy levels, p < 0.001), NK cells (45.4%, p < 0.001) and, most strikingly, B cells (5.3%, p < 0.001). G-CSF treatment, given to combat neutropenia, reduced the magnitude of the chemotherapy effect. B cell numbers post-therapy were significantly higher in patients who received G-CSF as compared to those who did not (7.6% versus 2.2%, p < 0.001), as were CD3+ cells (64.5% versus 34.8%, p = 0.001) and NK cells (81.0% versus 24.7%, p < 0.001).

B cell recovery was slow, reaching only 31.0% and 40.1% of initial levels by 3 and 6 months post-chemotherapy. Most repopulating B cells were naïve (CD27−) (pre-chemotherapy: 55.0% of total B cells; 3 months post-chemotherapy: 81.3%) with expanded populations of CD38hiCD24hi (pre-chemotherapy: 5.0%; 3 months post-chemotherapy: 20.8%) and CD5+CD1d+ (pre-chemotherapy: 19.0%; 3 months post-chemotherapy: 51.28%). Smoking had potent influences on B cell repopulation: smokers' B cells recovered to only 21.1% and 32.3% of pre-chemotherapy levels at 3 and 6 months as compared to 41.9% and 47.9% in non-smokers (p < 0.001). Smoking also affected subclasses within repopulating B cells, with smokers having a 3-fold greater proportion of switched memory B cells (p < 0.001). There was no statistically significant difference in B cell repopulation between patients who had radiotherapy along with chemotherapy and those who had chemotherapy alone. There was also no statistically significant difference in B cell depletion or recovery between different age groups, initial tumour size or grade of tumour.

Conclusions: These results confirm that B cells are especially vulnerable to chemotherapy toxicity. Detailed phenotyping of B cells revealed that chemotherapy has a profound effect on B cell subpopulations. The significance of this on host immunity is under investigation. We have additionally identified two factors responsible for delayed B cell repopulation, which highlight the need for lymphocyte assessments to be performed during and after chemotherapy.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-13-08.

CVID patients with autoimmunity have elevated T cell expression of granzyme B and HLA-DR and reduced levels of Treg cells

AIMS

Common variable immunodeficiency (CVID) is a primary antibody immunodeficiency with approximately 20% of patients reporting additional autoimmune symptoms. The primary aim of this study was to compare the levels of activated and regulatory T cells (Treg cells) in CVID patients in an attempt to clarify their possible interactions leading to the generation of autoimmunity.

METHODS

Immunophenotyping of T cells was performed by flow cytometry using a whole blood approach. Surface expression of human leukocyte antigen HLA class II DR and intracellular levels of granzyme B in T cell subsets were assessed; Treg levels were measured using CD4 CD25, FOXp3 and CTLA-4.

RESULTS

CVID patients had higher levels of granzyme B and HLA-DR on CD8(+) T cells compared with control values (mean of 59% vs 30% and 45% vs 21%, respectively). Patients also had reduced levels of Treg cells compared with control values (con mean=3.24% vs pat=2.54%). Patients with autoimmunity (5/23) had a similar level of T cell activation markers to the rest of the patients but with lower Treg cells (mean of 1.1%) and reduced CD25 and CTLA-4 expression. Patients with autoimmunity had a higher ratio of activated to Treg cells compared with patients with no autoimmune symptoms.

CONCLUSIONS

These results highlight that reduced levels of Treg cells were associated with elevated levels of activated T cells, suggesting that reduced Treg cells in these patients may have functional consequences in allowing exaggerated T cell responses.

Frequency of Treg cells is reduced in CVID patients with autoimmunity and splenomegaly and is associated with expanded CD21lo B lymphocytes

INTRODUCTION

Common variable immunodeficiency is a heterogeneous antibody deficiency syndrome with autoimmune and inflammatory complications in a significant proportion of patients. The study was designed to evaluate the role of T regulatory (Treg) cells in common variable immunodeficiency (CVID) patients with autoimmunity.

METHODS

The number and frequency of Treg cells (CD4(+), CD25(hi), Foxp3(+)) were evaluated in patients and controls, and Foxp3 expression in different subgroups of CVID patients with common clinical manifestations was compared.

RESULTS

CVID patients had significantly fewer Treg cells than controls, and low frequency of Treg cells was associated with expansion of CD21(lo) B cells in patients. Patients with autoimmunity had significantly reduced frequency but normal numbers of regulatory T cells, whilst patients with splenomegaly had significant reduction in frequency and number of regulatory T cells.

CONCLUSION

Foxp3 is useful on its own or as an adjunct to classify CVID patients although the possibility of reduction in Treg cells as a secondary phenomenon cannot be excluded.

Treatment of mice with IL-12 DNA constructs leads to augmented NK activity in lungs but low IFN-gamma release -- implications for Bordetella pertussis infections following aerosol challenge

Interleukin-12 protein has been widely used experimentally in therapeutic and adjuvant settings in the treatment of different diseases including intra-cellular bacterial infections. The in vivo clearance of Bordetella pertussis infections in naive mice and in animals vaccinated with whole cell vaccine is considered to be a Th-1 dependent mechanism. Furthermore, the addition of IL-12 protein to an acellular pertussis vaccine increases the efficacy of this vaccine. Whilst the use of IL-12 protein is often beneficial, a number of problems there are associated with this cytokine including toxicities and down regulation of normal immune functions. The use of DNA constructs encoding this cytokine may be a way of achieving maximum therapeutic benefit with minimum toxicity. The aims of this study were to optimise the effects of two IL-12 DNA constructs, especially with respect to augmenting pulmonary immune responsiveness and to compare the effect of IL-12 DNA and IL-12 protein on bacterial colonisation of lungs following aerosol challenge with B. pertussis. We found that IL-12 DNA constructs augmented the activity of pulmonary NK cells but had little effect on the course of B. pertussis infections in mice. In contrast to IL-12 protein, the DNA constructs had no immunosuppressive effects on splenic lymphocyte mitogen responses.

High dose interleukin-12 exacerbates Bordetella pertussis infection and is associated with suppression of cell-mediated immunity in a murine aerosol challenge model

The in-vivo clearance of Bordetella pertussis infections in murine models in naive mice and animals vaccinated with whole-cell vaccine is considered to be via a Th-1-dependent mechanism in which interleukin-12 (IL)-12 may play a prominent role. It has also been demonstrated clearly that the treatment of animals with macrophage-derived IL-12 administered with an acellular vaccine can increase the efficacy of this vaccine preparation to levels seen with the whole-cell vaccine. However, the effects of exogenously added IL-12 on immune responses in non-vaccinated B. pertussis-challenged mice remain unclear, with two studies giving contradictory findings. In this study we have treated mice with escalating doses of mIL-12 (0.1-10 microg/mouse) prior to challenge with B. pertussis (using an aerosol challenge model of infection). The ability of mice to clear infection was assessed in IL-12 treated and in phosphate buffered saline (PBS) control animals at days 6 and 13 post-challenge. Lymphoid cells were isolated from spleen and cell-mediated immune responses assessed at days 1, 6 and 13 post-challenge. In addition, the direct effects of high-dose IL-12 on challenged mice was assessed by checking natural killer (NK) activity from isolated lung and spleen lymphoid cells as well as interferon-gamma (IFN-gamma) generation from isolated cells and serum at day 1 post-challenge. The results from this study show that bacterial colonization of the lungs is actually enhanced following treatment with high-dose IL-12. This is associated with impaired cellular immune responses. The mechanisms associated with the immunosuppressive effects of IL-12 are discussed.

Human serum inactivates non-glycosylated but not glycosylated granulocyte colony stimulating factor by a protease dependent mechanism: significance of carbohydrates on the glycosylated molecule

It has previously been reported that the biological activity of the human hematopoetic cytokine granulocyte colony stimulating factor (G-CSF) was reduced following incubation with human serum. The mechanism of action of serum has remained elusive although a number of possible mechanisms have been suggested including inactivation due to binding to the serum protein alpha(2)-macroglobulin (alpha(2)M) and degradation by serum proteases. The aim of this study was to clarify the conditions required by serum to reduce the biological activity of the cytokine and to define the mechanism involved. It has also been noted that G-CSF obtained from a CHO expression system (and therefore considered a glycosylated molecule) was resistant to serum inactivation unlike G-CSF obtained from an E. coli expression system (considered to be non-glycosylated). We used an enzymatic approach to remove the carbohydrate residues from glycosylated G-CSF and tested this material for its stability in serum. We additionally used a mutated G-CSF lacking glycosylation sites. We concluded that glycosylation was important in protecting against serum inactivation. We observed that serum reduced the biological activity of non-glycosylated G-CSF in a dose, and temperature dependent manner and deduced that the mechanism of action was dependent upon alpha(2)M bound serum protease enzymes.

The effect of pertussis whole cell and acellular vaccines on pulmonary immunology in an aerosol challenge model

Recent clinical trials have shown that the new generation of acellular pertussis vaccines (Pa) can confer protection against whooping cough with negligible adverse reactions. We have compared the effects of pertussis whole cell and acellular vaccines on pulmonary immune responses after aerosol challenge in a murine model of infection. Mice were vaccinated with PBS, Pw or Pa and challenged with Bordetella pertussis by the aerosol route. Cytokine gene expression was analysed from lung tissue and cells; lung lymphocytes were re-stimulated in vitro and cytokines produced measured. The results obtained are consistent with the proposal that a strong Th-1 response is associated with bacterial clearance in both the non-vaccinated and Pw vaccinated mice. The acellular vaccine treated mice cleared the bacterial challenge (with an intermediate efficacy) in the presence of low levels of any of the cytokines assessed. This suggests that Pa protects via a Th-2 independent mechanism.

The significance of carbohydrates on G-CSF: differential sensitivity of G-CSFs to human neutrophil elastase degradation

It has been reported recently that granulocyte-colony stimulating factor (G-CSF) is degraded upon exposure to human neutrophil elastase (HNE), and this has a negative effect on the ability of the cytokine to promote the in vitro proliferation and maturation of CD34+ cells. This has important implications on the possible in vivo role of elastase in providing negative feedback to granulopoiesis by the direct antagonism of G-CSF. The cytokine used in that study was expressed in Escherichia coli [and was nonglycosylated (NG)], unlike the naturally occurring cytokine, which is an O-linked glycoprotein. As a Chinese hamster ovary-derived (glycosylated) cytokine is available, we compared the susceptibility of NG and glycosylated G-CSF to elastase degradation by incubating the cytokines with HNE and assessing its impact by sodium dodecyl sulfate gel electrophoresis and bioassay. We confirmed the ability of elastase to degrade NG G-CSF in a time- and concentration-dependent manner and found this was associated with a reduction in biological activity of the cytokine. Glycosylated G-CSF, however, was more resistant to elastase degradation, although prolonged exposure did lead to degradation and decreased biological activity. The significance of sugar residues on glycosylated G-CSF in providing protection against the effects of elastase was investigated using enzymatically deglycosylated G-CSF and a mutated form of the G-CSF molecule that was expressed in yeast but was NG. The possible role of HNE in serum-induced inactivation of NG G-CSF was also considered.

Tumor-specific CTL kill murine renal cancer cells using both perforin and Fas ligand-mediated lysis in vitro, but cause tumor regression in vivo in the absence of perforin

Kidney cancer is a devastating disease; however, biological therapies have achieved some limited success. The murine renal cancer Renca has been used as a model for developing new preclinical approaches to the treatment of renal cell carcinoma. Successful cytokine-based approaches require CD8(+) T cells, but the exact mechanisms by which T cells mediate therapeutic benefit have not been completely identified. After successful biological therapy of Renca in BALB/c mice, we generated CTLs in vitro using mixed lymphocyte tumor cultures. These CTL mediated tumor-specific H-2K(d)-restricted lysis and production of IFN-gamma, TNF-alpha, and Fas ligand (FasL) in response to Renca. CTL used both granule- and FasL-mediated mechanisms to lyse Renca, although granule-mediated killing was the predominant lytic mechanism in vitro. The cytokines IFN-gamma and TNF-alpha increased the sensitivity of Renca cells to CTL lysis by both granule- and FasL-mediated death pathways. Adoptive transfer of these anti-Renca CTL into tumor-bearing mice cured most mice of established experimental pulmonary metastases, and successfully treated mice were immune to tumor rechallenge. Interestingly, we were able to establish Renca-specific CTL from mice gene targeted for perforin (pfp(-/-)) mice. Although these pfp(-/-) CTL showed reduced cytotoxic activity against Renca, their IFN-gamma production in the presence of Renca targets was equivalent to that of wild-type CTL, and adoptive transfer of pfp(-/-) CTL was as efficient as wild-type CTL in causing regression of established Renca pulmonary metastases. Therefore, although granule-mediated killing is of paramount importance for CTL-mediated lysis in vitro, some major in vivo effector mechanisms clearly are independent of perforin.