Slow recovery of follicular B cells and marginal zone B cells after chemotherapy: implications for humoral immunity

Protective effect of Echinacea purpurea (Immulant) against cisplatin-induced immunotoxicity in rats

PURPOSE

Cisplatin, one of the most effective anticancer drugs, is known to cause undesirable adverse effects, including immunotoxicity. Echinacea purpurea is an important medicinal plant with immunostimulatory and anti-inflammatory activities. We have investigated the protective effect of an herbal formulation (Immulant) containing E. purpurea extract against cisplatin-induced immunotoxicity in rats.

METHODS

Forty mature albino rats were randomized into four groups (10 rats/group). Control (group 1) animals were subjected to intraperitoneal (i.p.) injection of saline solution (0.2 ml) once every 3 days. Group 2 animals received cisplatin (3.5 mg/kg, i.p.) once every 3 days for successive 2 weeks. Group 3 rats received oral Immulant (150 mg/kg) once daily for 2 weeks. Group 4 animals received oral Immulant treatment as in group 3 in addition to cisplatin as in group 2. Serum level of total protein and albumin, total and differential leukocytic count, phagocytic activity of monocytes, humoral activity and splenic histopathology and immunohistochemistry were used as diagnostic markers of immunotoxicity.

RESULTS

Cisplatin induced marked inhibition of cellular immunity as exhibited by significant decrease of leukocytic count, lymphocyte percentage and phagocytic activity with marked increase in neutrophil percentage. Humoral immunity represented by marked inhibition in total protein and γ-globulin concentration and significant inhibition in antibody titer against Mycoplasma gallisepticum were recorded. Histopathological and immunohistochemical observation of the spleen of cisplatin-treated rats revealed obvious pathological findings of marked depletion and degeneration of lymphoid tissue. Co-oral administration of Immulant resulted in substantial improvement of various immunotoxicological indices compared to cisplatin control.

CONCLUSION

The herbal medicine Immulant is an immunostimulant which could be used to treat the immunotoxic effects of cisplatin. Graphical abstract Cisplatin (CP) is a highly effective antineoplastic DNA alkylating agent. CP induces free radical production causing an oxidative damage.Cisplatin induced marked inhibition in cellular and humoral immunityEchinacea purpurea (Immulant) is a powerful anticytotoxic agent against cisplatin toxicity.

B cell homeostasis is disturbed by immunosuppressive therapies in patients with ANCA-associated vasculitides

B-lymphocytes play a pivotal role in ANCA-associated vasculitides (AAV). The homeostasis of peripheral human B-lymphocyte subpopulations is tightly regulated, but may be disturbed in autoimmune disease or following immunosuppressive therapies. To elucidate the effect of immunosuppression and the relevance of B-lymphocyte disturbances, the B-lymphocyte compartment was analysed in 61 AAV patients. After immunosuppressive treatment a general B-lymphocytopenia developed in AAV patients. Within the B-lymphocyte subpopulations transitional B cells are the first maturation stage found in the peripheral blood. Transitional B-lymphocytes were significantly lower in AAV patients after immunosuppressive therapy compared to healthy controls. Furthermore, marginal zone B cells--a B-lymphocyte population protecting against encapsulated bacteria--were markedly lowered after immunosuppressive therapy in AAV patients. AAV patients treated with immunosuppressants had lower numbers of naïve and memory B-lymphocytes. Numbers of marginal zone B cells, memory B cells and plasmablasts correlated with concentrations of immunoglobulins. We evaluated plasmablasts for a potential correlation with disease activity. Different from what has been reported for e.g. large vessel vasculitis, absolute numbers of plasmablasts were not increased in patients with AAV and showed no correlation to disease activity. As low transitional B cells after treatment with immunosuppressants indicated an impaired early B-lymphocyte development, seven patients treated with the B cell depleting agent rituximab (RTX) because of relapsing disease activity were analysed for their B cell repopulation kinetics. In the majority of these patients repopulation of the peripheral B cell compartment by newly formed transitional B cells after RTX treatment was constricted and delayed.

Egyptian sweet marjoram leaves protect against genotoxicity, immunosuppression and other complications induced by cyclophosphamide in albino rats

Cyclophosphamide (CP) is one of the most popular alkylating anticancer drugs that show a high therapeutic index, despite the widespread side effects and toxicity particularly in high-dose regimens and long-term use. Here, we evaluated and compared the efficacy of two different doses (50 and 100 mg/kg body weight, given orally for 30 consecutive days) of Egyptian sweet marjoram leaf powder (MLP) and marjoram leaf aqueous extract (MLE) in alleviating the genotoxicity, immunosuppression and other complications induced by CP in non-tumour-bearing albino rats. The present study showed (probably for the first time) that both MLP and MLE significantly alleviated (P < 0·05–0·001) most side effects and toxicity of CP-treated rats including the increase in chromosomal aberrations of bone marrow cells and serum malondialdehyde level, the decrease in the level of serum Ig, the delayed type of hypersensitivity response as also the weights and cellularity of lymphoid organs, and myelosuppression, leucopenia, macrocytic normochromic anaemia as well as thrombocytopenia by reactivating the non-enzymic (reduced glutathione) and enzymic (catalase, glutathione peroxidase, glutathione S-transferase, superoxide dismutase) antioxidant system and increasing the mitotic index of bone marrow cells. The modulatory effects of marjoram leaves shown in the present study were dose dependent in most cases and much higher in MLE (21–23 % for all parameters taken together). In addition, the doses used in the present study were considered safe. In conclusion, sweet marjoram leaves (especially in the form of a herbal tea) may be useful as an immunostimulant and in reducing genotoxicity in patients under chemotherapeutic interventions.

A semi-physiological-based pharmacokinetic/pharmacodynamic model to describe the effects of topotecan on b-lymphocyte lineage cells

PURPOSE

To develop a semi-physiological-based model describing simultaneously the time course of immature and mature B-lymphocytes after topotecan (TPT) administration to tumor-bearing rats.

METHODS

Twenty-four tumor-bearing BDIX male rats received a single 6 mg/kg intra-peritoneal dose of TPT or saline. Mature and immature B-cell levels were measured every two days during three weeks and showed a very different temporal pattern. Both B-cell populations declined rapidly, reaching the nadir at 3-4 days after TPT administration; however, mature cells returned to baseline at day 8, while immature B-cells stayed at nadir until day 9 instead. Data were modeled using the population approach with NONMEM VI.

RESULTS

The model developed maintains the proliferation, maturation and degradation elements of previous published models for myelosuppresion. In order to describe the rapid recovery of mature cells, it includes a peripheral compartment providing a constant supply of mature cells to the bloodstream.

CONCLUSIONS

The major contribution of the model is its new structure and the dynamical consequences, demonstrating an independent behavior between mature and immature B-cells during recovery. The final model could represent a good basis for the optimization of cytotoxic drugs oriented to attain a maximum antitumor efficacy while minimizing hematological toxicity.

Complement dependency of splenic localization of pneumococcal polysaccharide and conjugate vaccines

The immune response to polysaccharides is initiated when polysaccharides bind complement factor C3d, and these polysaccharide-C3d complexes subsequently localize on splenic marginal zone B cells strongly expressing CD21 (complement receptor 2). Infants and children under the age of 2 years have low or absent expression of CD21 on their marginal zone B cells, and consequently do not adequately respond to polysaccharides. In contrast, polysaccharide-protein conjugate vaccines are able to induce antibodies at this young age. Conjugate vaccines apparently overcome the necessity for CD21-C3d interaction for an antipolysaccharide immune response. We demonstrate in a rat model that localization of pneumococcal polysaccharides on splenic marginal zone B cells indeed is complement dependent. We also show that pneumococcal conjugates do not specifically localize on splenic marginal zone B cells and that splenic localization of polysaccharide conjugates is independent of the presence of complement. Thus, the induction of antipolysaccharide antibodies by conjugate vaccines apparently can occur independently of CD21-C3d interaction. These basic findings may explain the effectiveness of conjugated vaccines in young children and may open the way for their application in other patient groups.

Noradrenergic responses of peripheral organs to cyclophosphamide in mice

To determine if the chemotherapeutic drug cyclophosphamide influences the activity of the sympathetic nervous system, the effects of cyclophosphamide on norepinephrine concentration in the heart, adrenal gland, spleen, and thymus gland were evaluated. Male BALB/cByJ mice were administered a single injection of cyclophosphamide (15, 50, or 100 mg/kg, i.p) or saline-vehicle. Organs were collected 72 or 120 h after injection and norepinephrine concentrations were determined by high pressure liquid chromatography with electrochemical detection. Cyclophosphamide reduced spleen, thymus gland, and heart mass while also elevating spleen and thymus gland norepinephrine concentrations (both pmoles/mg tissue and pmoles/mg protein) in a dose- and time-dependent manner. Norepinephrine concentrations in heart and adrenal gland were not altered by cyclophosphamide at any drug dose or time point. Dose- and time-dependent cyclophosphamide-mediated changes in peripheral norepinephrine levels in the spleen and thymus gland are interesting because subjects administered cyclophosphamide may be more susceptible to opportunistic infections, not only because the drug is antineoplastic, but also because the drug alters nervous system-immune system communication and the neurochemical milieu in which surviving cells interact.

Cyclophosphamide induces dose- and time-dependent elevations in spleen norepinephrine levels of BALB/c mice

Chemotherapeutic drugs may not only kill rapidly dividing cells but may also alter the extracellular environment of surviving cells. We investigated the possibility that cyclophosphamide might alter the noradrenergic environment of the spleen. Male BALB/cByJ mice were administered a single injection of cyclophosphamide (0, 15, 50, or 100 mg/kg). Seventy-two hours after injection animals receiving 50 or 100 but not 15 mg/kg experienced elevated norepinephrine concentrations (pmol/mg) compared to animals given 0 mg/kg. The time course of changes in norepinephrine concentration was investigated 24-216 h after administration of 50 mg/kg cyclophosphamide; norepinephrine took 48 h to elevate, remained elevated for 48-96 h, and returned to vehicle-treated levels by 120 h. Cyclophosphamide in both experiments reduced spleen mass but did not alter total norepinephrine/spleen. These results suggest that low doses of cyclophosphamide can increase the norepinephrine available to influence cell-cell interactions in the spleen.

Effects of multidose combination chemotherapy on the humoral immune system

Patients receiving multidose combination chemotherapy are at risk for severe, life-threatening infections, caused by among others encapsulated bacteria like Streptococcus pneumoniae. The splenic marginal zone is essential in the initiation of immune responses to S. pneumoniae. We analyzed effects of multidose combination chemotherapy on B-cell subpopulations. Immune response capacity was evaluated by using Pneumovax (PPS) or Tetavax (TT) as antigenic challenge. Three days after finishing therapy, all B-cell subpopulations in bone marrow and spleen were severely reduced, including the mature marginal zone B-cell population. When analyzing the anti-PPS immune response capacity at 3 days after finishing therapy, we found that the IgM antibody levels did not differ significantly from control immunized rats. The IgG antibody levels were significantly lower compared to control immunized rats but still significantly higher compared to unimmunized rats. The depletion of marginal zone B cells by multidose combination chemotherapy most likely contributes to the prolonged period that patients are at risk for developing severe infections after chemotherapy, despite the capacity to generate sufficient antibody levels. It is conceivable that the local (temporary) loss of immunological memory, together with the supposed inability to generate a humoral response in a short time frame, plays an important role in this vulnerability.

After chemotherapy, functional humoral response capacity is restored before complete restoration of lymphoid compartments

Chemotherapy has, besides the beneficial effects, several adverse effects. Suppression of the immune system is one of the most important problems. Infections caused by encapsulated bacteria like Streptococcus pneumoniae are responsible for a major part of infectious problems during and after treatment. The splenic marginal zone is essential in the initiation of an immune response to encapsulated bacteria. In this study, we analysed the effects of three different cytostatic agents on humoral immune responses. We found a reduced, but detectable immune response capacity at two days after treatment although the marginal zone B cell population is severely reduced at this time point. Twenty-four days after cessation of treatment, the immune response capacity was largely restored although lymphoid compartments were still not completely restored at that time point. Apparently, the presence of only few marginal zone B cells is sufficient to evoke a rise in antibody titres and although antibody titre increases are low, even small rises are most likely clinically relevant.

Structure-function relationships for human antibodies to pneumococcal capsular polysaccharide from transgenic mice with human immunoglobulin Loci

To investigate the influence of antibody structure and specificity on antibody efficacy against Streptococcus pneumoniae, human monospecific antibodies (MAbs) to serotype 3 pneumococcal capsular polysaccharide (PPS-3) were generated from transgenic mice reconstituted with human immunoglobulin loci (XenoMouse mice) vaccinated with a PPS-3-tetanus toxoid conjugate and their molecular genetic structures, epitope specificities, and protective efficacies in normal and complement-deficient mice were determined. Nucleic acid sequence analysis of three MAbs (A7, 1A2, and 7C5) revealed that they use two different V(H)3 genes (A7 and 1A2 both use V3-15) and three different V(kappa) gene segments. The MAbs were found to have similar affinities for PPS-3 but different epitope specificities and CDR3 regions. Both A7 and 7C5 had a lysine at the V(H)-D junction, whereas 1A2 had a threonine. Challenge experiments with serotype 3 S. pneumoniae in BALB/c mice revealed that both 10- and 1- micro g doses of A7 and 7C5 were protective, while only a 10- micro g dose of 1A2 was protective. Both A7 and 7C5 were also protective in mice lacking either an intact alternative (FB(-/-)) or classical (C4(-/-)) complement pathway, but 1A2 was not protective in either strain. Our data suggest that PPS-3 consists of epitopes that can elicit both highly protective and less protective antibodies and that the superior efficacies of certain antibodies may be a function of their structures and/or specificities. Further investigation of relationships between structure, specificity, and efficacy for defined MAbs to PPS may identify antibody features that might be useful surrogates for antibody (and vaccine) efficacy.