The hippocampus and delayed recall: bigger is not necessarily better?

Healthy young female participants were tested on a measure of delayed verbal recall and then received volumetric Magnetic Resonance Imaging (MRI) scans. The analysis of the MRI scans focused on the volume of the hippocampus. Left hippocampal volume was negatively associated with the level of delayed verbal recall performance. This relationship was confirmed in further testing. This finding is consistent with a previous report of a similar relationship in healthy elderly individuals, but not in patients with Alzheimer's disease, in whom the opposite relationship was observed. An explanation of these findings in terms of impaired neural pruning of the hippocampus is advanced, whereby insufficient pruning of the hippocampus during childhood and adolescence (following adequate growth) may lead to reduced mnemonic efficiency.

Nonequilibrium critical behavior in unidirectionally coupled stochastic processes

Phase transitions from an active into an absorbing, inactive state are generically described by the critical exponents of directed percolation (DP), with upper critical dimension d(c)=4. In the framework of single-species reaction-diffusion systems, this universality class is realized by the combined processes A-->A+A, A+A-->A, and A-->0. We study a hierarchy of such DP processes for particle species A,B,..., unidirectionally coupled via the reactions A-->B, ...(with rates mu(AB),...). When the DP critical points at all levels coincide, multicritical behavior emerges, with density exponents beta(i) which are markedly reduced at each hierarchy level i> or =2. This scenario can be understood on the basis of the mean-field rate equations, which yield beta(i)=1/2(i-1) at the multicritical point. Using field-theoretic renormalization-group techniques in d=4-epsilon dimensions, we identify a new crossover exponent phi, and compute phi=1+O(epsilon(2)) in the multicritical regime (for small mu(AB)) of the second hierarchy level. In the active phase, we calculate the fluctuation correction to the density exponent on the second hierarchy level, beta(2)=1/2-epsilon/8+O(epsilon(2)). Outside the multicritical region, we discuss the crossover to ordinary DP behavior, with the density exponent beta(1)=1-epsilon/6+O(epsilon(2)). Monte Carlo simulations are then employed to confirm the crossover scenario, and to determine the values for the new scaling exponents in dimensions d< or =3, including the critical initial slip exponent. Our theory is connected to specific classes of growth processes and to certain cellular automata, and the above ideas are also applied to unidirectionally coupled pair annihilation processes. We also discuss some technical as well as conceptual problems of the loop expansion, and suggest some possible interpretations of these difficulties.

A conformationally-constrained MHC class II I-Ag7-derived peptide protects NOD mice from the development of diabetes

Allele-specific peptide vaccination against disease-associated MHC class II molecules is a promising new strategy for modulating self-antigen presentation to autoreactive T cells in autoimmune diseases. To evaluate the potential of this approach for treatment of insulin-dependent diabetes mellitus (IDDM), we have designed a cyclic peptide vaccine, DiavaX, from the third hypervariable region of the beta-chain of the NOD mouse MHC class II I-Ag7. NOD mice were treated at 5 and 9 weeks of age with 100 microg DiavaX emulsified in alum, a control peptide in alum, or alum alone. At the end of the study, 87% of alum treated mice had developed diabetes, compared with only 28% of DiavaX-treated mice. None of the control peptides, including a linear I-Ag7, a scrambled cyclic I-Ag7, or an analogous cyclic I-Aspeptide, reduced the incidence of diabetes, demonstrating that the protective effect of DiavaX is conformationally dependent and both allele- and sequence-specific. DiavaX treatment did not cause any general immune suppression, but did induce peptide-specific antibodies and memory T cells. DiavaX-induced protection from diabetes was associated with the maintenance of a non-destructive islet-associated autoimmune response. These data indicate that a conformationally constrained peptide from the disease-associated MHC represents a potential vaccine candidate for the prevention of clinical IDDM.

Physical characterization of a low-charge glycoform of the MUC5B mucin comprising the gel-phase of an asthmatic respiratory mucous plug

We have previously noted that sequential extraction of an asthmatic mucous exudate with 6 M guanidinium chloride yielded a fraction of the mucins that were most resistant to solubilization and of high Mr [Sheehan, Richardson, Fung, Howard and Thornton (1995) Am. J. Respir. Cell Mol. Biol. 13, 748-756]. Here we show that this mucin fraction is dominated (at least 96% of the total) by the low-charge glycoform of the MUC5B gene product. Seen in the electron microscope the mucins appeared mainly as compact 'island' structures composed of linear threads often emanating from globular 'nodes' rather than the discrete linear threads more typical of mucins that we have previously described. The effect of reducing agents was as expected for other gel-forming mucins, i.e. reduced subunits or monomers of Mr 3x10(6)) were produced within 15 min of treatment. Kinetic experiments on the cleavage of the intact mucins with the proteinase trypsin indicated two clear regimes of fragmentation. An initial rapid cleavage generated mucins ranging from Mr=4x10(6) to 30x10(6) that in the electron microscope appeared as polydisperse threads (500-3000 nm in length), similar to normal and other respiratory mucins that we have previously characterized. A subsequent slower fragmentation over many hours yielded a major fragment of Mr 3x10(6) and length 200-600 nm, very similar in size and Mr to the subunits obtained by reduction. The results suggest that the MUC5B mucin is assembled, first into polydisperse linear threads, which are then linked together via a protein-mediated process. This might involve part of the mucin polypeptide or an as yet unidentified protein(s). The high proteinase susceptibility of the linkage suggests that it might be a point of control for mucin size and thus mucus rheology.

Salivary mucin MG1 is comprised almost entirely of different glycosylated forms of the MUC5B gene product

The MG1 population of mucins was isolated from human whole salivas by gel chromatography followed by isopycnic density gradient centrifugation. The reduced and alkylated MG1 mucins, separated by anion exchange chromatography, were of similar size (radius of gyration 55-64 nm) and molecular weight (2.5-2.9 x 10(6) Da). Two differently-charged populations of MG1 subunits were observed which showed different reactivity with monoclonal antibodies to glycan epitopes. Monosaccharide and amino acid compositional analyses indicated that the MG1 subunits had similar glycan structures on the same polypeptide. An antiserum recognizing the MUC5B mucin was reactive across the entire distribution, whereas antisera raised against the MUC2 and MUC5AC mucins showed no reactivity. Western blots of agarose gel electrophoresis of fractions across the anion exchange distribution indicated that the polypeptide underlying the mucins was the product of the MUC5B gene. Amino acid analysis and peptide mapping performed on the fragments produced by trypsin digestion of the two MG1 populations yielded data similar to that obtained for MUC5B mucin subunits prepared from respiratory mucus (Thornton et al., 1997) and confirmed that the MUC5B gene product was the predominant mucin polypeptide present. Isolation of the MG1 mucins from the secretions of the individual salivary glands (palatal, sublingual, and submandibular) indicate that the palatal gland is the source of the highly charged population of the MUC5B mucin.

[Minimally invasive coronary artery surgery]

BACKGROUND

There is a growing interest to perform a left internal mammary artery (LIMA) graft to the left anterior descending coronary artery (LAD) on a beating heart through a minimally invasive access to the chest cavity.

AIM

To report the experience with minimally invasive coronary artery surgery.

PATIENTS AND METHODS

Analysis of 11 patients aged 48 to 79 years old with single vessel disease that, between 1996 and 1997, had a LIMA graft to the LAD performed through a minimally invasive left anterior mediastinotomy, without cardiopulmonary bypass. A 6 to 10 cm left parasternal incision was done. The LIMA to the LAD anastomosis was done after pharmacological heart rate and blood pressure control and a period of ischemic pre conditioning. Graft patency was confirmed intraoperatively by standard Doppler techniques. Patients were followed for a mean of 11.6 months (7-15 months).

RESULTS

All patients were extubated in the operating room and transferred out of the intensive care unit on the next morning. Seven patients were discharged on the third postoperative day. Duplex scanning confirmed graft patency in all patients before discharge; in two patients, it was confirmed additionally by arteriography. There was no hospital mortality, no perioperative myocardial infarction and no bleeding problems. After follow up, ten patients were free of angina, in functional class I and pleased with the surgical and cosmetic results. One patient developed atypical angina on the seventh postoperative month and a selective arteriography confirmed stenosis of the anastomosis. A successful angioplasty of the original LAD lesion was carried out.

CONCLUSIONS

A minimally invasive left anterior mediastinotomy is a good surgical access to perform a successful LIMA to LAD graft without cardiopulmonary bypass, allowing a shorter hospital stay and earlier postoperative recovery. However, a larger experience and a longer follow up is required to define its role in the treatment of coronary artery disease.

AKAP79 inhibits calcineurin through a site distinct from the immunophilin-binding region

Targeting of protein kinases and phosphatases provides additional specificity to substrate selectivity in cellular signaling. In the case of the Ca2+/calmodulin-dependent protein phosphatase calcineurin, AKAP79 has been shown to bind calcineurin and inhibit its activity in vitro (Coghlan, V., Perrino, B. A., Howard, M., Langeberg, L. K., Hicks, J. B., Gallatin, W. M., and Scott, J. D. (1995) Science 267, 108-111). In the present study, we characterized the binding regions on calcineurin A (CnA) and AKAP79 that are important for this interaction. Residues 30-98 and 311-336 on CnA, and residues 108-280 on AKAP79 were found to be important for binding. The binding of CnA by AKAP79 does not require the calcineurin B subunit, and occurs in a region distinct from where the immunosuppressant-immunophilin complex bind. AKAP79 also bound to CnA in cells transfected with AKAP79 and CnA. To determine the function of AKAP79-calcineurin interaction in intact cells, we measured the dephosphorylation and subsequent activation of NFAT, a transcription factor that is a substrate for calcineurin. Overexpression of AKAP79 inhibited NFAT dephosphorylation, resulting in a decrease in NFAT activation. These results demonstrated that AKAP79 can bind to and inhibit calcineurin activity in vivo, suggesting a physiological role for AKAP79-calcineurin interaction in NFAT-mediated signaling.

The role of alternative splicing of the adhesion molecule, CD44, in lymphoid malignancy

AIM

To investigate the expression of CD44 isoforms containing variant exon 6 (v6) in a well characterised cohort of patients with non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukaemia (CLL), and to correlate this with phenotype and disease course.

METHODS

Cryostat sections of OCT embedded diagnostic nodal material from NHL patients and cryopreserved mononuclear preparations from CLL patients were used as sources of RNA. After reverse transcription, PCR was carried out with amplimers positioned at either side of the variant exon insertion site to amplify all possible CD44 isoforms. Those isoforms containing v6 were identified after Southern blotting and hybridisation with a radiolabelled oligonucleotide.

RESULTS

Of 32 NHL samples analysed, 16 did not express CD44 isoforms containing v6, six expressed an isoform containing exon v6 alone, and 10 expressed v6 long isoforms which contained exon v6 in addition to other variant exons. These data did not correlate with lymphoma classification, disease staging, or the presence or absence of extranodal disease. However, those patients expressing v6 long CD44 isoforms had a worse overall survival than those that did not. The plateau of the survival curves was 50% compared with 82%. No v6 long isoforms were detected in the 21 CLL samples investigated.

CONCLUSIONS

The expression of v6 long CD44 isoforms is associated with aggressive disease in NHL, independent of grade, stage, or presence of extranodal disease.

Interactive case challenge. Dysphoric disorders in women: a case of premenstrual syndrome

When this woman's long-standing PMS grows progressively more severe over the 3 years following the birth of her third child, what pharmacologic and nonpharmacologic treatments would you recommend? Symptoms of mood swings, irritability, and anxiety occur in many women during the premenstrual phase of the menstrual cycle. Several promising treatment options now exist for women whose symptoms are severe and interfere with daily functioning. These include nonpharmacologic as well as pharmacologic interventions, such as serotonergic antidepressants, anxiolytics, and hormones that suppress ovulation. When PMS becomes intolerably severe for this 36-year-old mother of 3 children--all under 10 years of age--she seeks treatment.

Practice what we preach? HIV knowledge, beliefs, and behaviors of adolescents and adolescent peer educators

The purpose of this article is to (a) describe the knowledge, beliefs, and sexual behaviors of urban adolescents and adolescent peer educators, and (b) identify elements needed to design effective HIV/AIDS prevention programs for out-of-school youth. Thirty-three predominantly African American adolescents (female = 14; male = 19) between the ages of 14 and 24 in a large urban city including adolescent (n = 18) and adolescent peer educators (n = 15) participated. Paper-and-pencil questionnaire and focus-group interviewing methods were used. Adolescents and adolescent peer educators had a moderately high level of HIV knowledge, confidence in their ability to use condoms, and beliefs that condom use would not decrease sexual pleasure or imply infidelity. Both groups reported low perceptions of susceptibility of HIV infection. Engagement in sexual risk behavior was low, but was significantly higher among males. Although adolescent male peer educators engaged in a higher frequency of risk behaviors over time, they had a lower frequency of sexual risk behaviors in the past 2 months compared with male adolescents. Study findings showed that HIV prevention interventions need to include information about specific risk behaviors, such as using condoms for oral sex, and cleaning drug paraphernalia. Community-based and church programs, visible HIV prevention messages, specifically those aimed at increasing perceptions of HIV risk, and the development of condom-use skills were identified by adolescents and adolescent peer educators as relevant approaches to reduce HIV infection among this population.

Measurement of adenosine concentration in aqueous and vitreous

PURPOSE

The release of adenosine by the ischemic retina may be an initial signal in the development of ischemic macular edema and neovascularization. The levels of adenosine have never been quantified in ocular fluids. In this study, a technique was developed for in vivo measurement of the concentration of adenosine in aqueous and vitreous.

METHODS

Aqueous and vitreous samples were obtained from bovine eyes after death and from live porcine eyes with the subject under general anesthesia. Samples from live eyes were immediately incubated in the sampling syringe with pentoxifylline, erythro-9-(2-hydroxy-3-nonyl) adenine, and dipyridamole to prevent synthesis or degradation of adenosine during the collection procedure, filtered, and flash-frozen in liquid nitrogen. All samples were then filtered and purified on phenylboronate agarose columns and incubated with chloroacetaldehyde to convert the adenosine present in the sample to the fluorescent derivative 1,N6-ethenoadenosine. The 1,N6-ethenoadenosine was separated by high-pressure liquid chromatography and then measured by fluorometry.

RESULTS

Levels of adenosine as low as 0.5 pmole could be detected with this procedure, compared with 20 pmoles by UV detection. By using this technique to measure adenosine levels in the eyes of normal weanling domestic pigs, it was determined that the adenosine concentration in the aqueous was 321.3 +/- 164.9 nM and in the vitreous was 210.8 +/- 41.5 nM.

CONCLUSIONS

The conversion of adenine-containing compounds to fluorescent 1,N6-etheno derivatives offers analytical advantages of selectivity and sensitivity for the quantitative determination of these compounds, with the fluorometric detection providing substantially greater sensitivity than direct detection by UV absorption. The levels obtained in vivo from anesthetized but otherwise healthy pigs presumably reflected basal aqueous and vitreous adenosine levels under the described conditions. This method should be useful in investigating more directly the role of adenosine in models of retinal or ocular ischemia in vivo and in measuring adenosine levels in vitreous or aqueous samples from human patients.

Predictors of positivity for hepatitis B and the derivation of a selective screening rule in a Canadian sexually transmitted disease clinic

OBJECTIVES

To determine the prevalence of hepatitis B surface antibody (anti-HBs) and antigenemia (HBsAg), the risk factors for seropositivity and the effectiveness of a selective serologic screening rule among sexually transmitted diseases (STD) clinic attendees.

STUDY DESIGN

Clients in the Hamilton STD Clinic were surveyed from October 1992 to July 1993 on sociodemographic, past medical, and behavioural data, were tested for several STDs and were offered serological testing and vaccination against hepatitis B. Predictors of seropositivity were determined by single variable analysis. A selective serologic screening rule was derived using logistic regression modelling.

RESULTS

The seroprevalence of anti-HBs was 6.8% (21/310) in the 310 of 385 clients (80.5%) who agreed to be tested and interviewed. There were no HBsAg carriers. Five independent risk factors were identified by logistic regression: (1) age greater than 35 years; (2) birth outside Canada and histories of; (3) syphilis; (4) gonorrhoea; or (5) injection drug use. If clients with at least one of these predictors had been tested, 34.5% would have been selected for serologic testing and 85.7% of all positives would have been detected. The screening rule was more effective for men than for women.

CONCLUSION

In this low prevalence setting, selecting STD clinic clients based on the presence of any one of five risk predictors appears to be an effective strategy for hepatitis B serologic screening in the context of a Canadian vaccination program.

Dysphoric disorders in women: a case of perinatal depression

During her third pregnancy, a woman becomes preoccupied with illness and death. When the dysphoria continues after her child is born, how would you evaluate and manage the problem?

Antigen-initiated B-lymphocyte differentiation. XVII. The inhibitory effects of recent antigen prepriming on the subsequent responsiveness of 'pre-progenitor' B cells

We have analysed the transient unresponsiveness of B cells following specific antigen prepriming. The effect is restricted to adoptive-transfer antibody-forming cell (AFC) progenitors (that is, 'pre-progenitors') and does not occur with the separate subset of cell culture AFC progenitors ('direct progenitors'). The transient unresponsiveness is displayed by both primary and secondary 'pre-progenitor' B cells. Mixing experiments and experiments with athymic mice indicate that the effect is not due to suppressor T cells or other inhibitory cells. Nor is the effect due to an impaired seeding ability of the activated or antigen-binding cells, since after adoptive transfer the preprimed cells can be activated by an appropriate non-specific stimulus. The most likely explanation involves direct interaction of specific antigen with the antigen receptors on 'pre-progenitor' B cells, rendering these cells more prone to temporary or permanent 'tolerance' on further antigen contact or, alternatively, directing their differentiation away from IgM AFC production on day 8 after transfer.

Transgene expression of bcl-xL permits anti-immunoglobulin (Ig)-induced proliferation in xid B cells

Mutations in the tyrosine kinase, Btk, result in a mild immunodeficiency in mice (xid). While B lymphocytes from xid mice do not proliferate to anti-immunoglobulin (Ig), we show here induction of the complete complement of cell cycle regulatory molecules, though the level of induction is about half that detected in normal B cells. Cell cycle analysis reveals that anti-Ig stimulated xid B cells enter S phase, but fail to complete the cell cycle, exhibiting a high rate of apoptosis. This correlated with a decreased ability to induce the anti-apoptosis regulatory protein, Bcl-xL. Ectopic expression of Bcl-xL in xid B cells permitted anti-Ig induced cell cycle progression demonstrating dual requirements for induction of anti-apoptotic proteins plus cell cycle regulatory proteins during antigen receptor mediated proliferation. Furthermore, our results link one of the immunodeficient traits caused by mutant Btk with the failure to properly regulate Bcl-xL.

Production and characterization of canine osteosarcoma cell lines that induce transplantable tumors in nude mice

OBJECTIVE

To produce and characterize cell lines from canine primary appendicular osteosarcomas that induce transplantable tumors in athymic nude mice.

ANIMALS

57 six- to 8-week-old female athymic nude mice.

PROCEDURE

Canine primary appendicular osteosarcoma tumors were harvested and cell lines were produced. Canine osteosarcoma (COSCA)-Toby (COSCA-T; 10 mice), COSCA-Princess (COSCA-Pr; 16) or canine osteosarcoma D-17 (ATCC CCL-183; 31) cells were injected into the proximal portion of the left tibia of nude mice to evaluate tumor production from each cell line; the right tibia served as the control. Tibial measurements were taken on alternating days to evaluate tumor growth during a 6-month period. Student's t-tests were used to determine whether size of the proximal portion of the left and right tibias differed significantly during the observation period.

RESULTS

88% of mice receiving COSCA-Pr and 50% of mice receiving COSCA-T cells developed a tumor at the injection site by 9 days after implantation. The D-17 cells induced tumors in 50% of injected tibias; however, tumors were not detected for 79 days. Tumors generated from COSCA-Pr and COSCA-T cells in nude mice were histologically similar to the canine tumor from which they were developed.

CONCLUSION

New osteosarcoma cell lines that can reliably and rapidly induce transplantable tumors in nude mice were developed.

CLINICAL RELEVANCE

Use of cell lines will allow evaluation of new treatments of canine primary appendicular osteosarcoma in a nude mouse model.

Chlamydial cervicitis: testing the practice guidelines for presumptive diagnosis

OBJECTIVE

To test the recommendation from the Canadian guidelines for sexually transmitted diseases (STDs) that mucopurulent endocervical discharge and 10 or more polymorphonuclear leukocytes (PMNs) per high-power field of a Gram-stained endocervical smear or, when Gram staining is not possible, the presence of endocervical discharge and one of edema, erythema or induced mucosal bleeding of the cervix can be considered diagnostic for chlamydial cervicitis.

METHODS

A total of 596 consecutive women attending 2 family planning clinics for routine care underwent vaginal speculum examination and were tested for Chlamydia trachomatis and Neisseria gonorrhoeae. PMN counts from Gram-stained endocervical smears and the presence or absence of putative indicators of chlamydial infection were recorded.

RESULTS

The prevalence of chlamydial cervicitis was 6.2% (37/596), and no women tested positive for N. gonorrhoeae. Presumptive diagnosis of chlamydial cervicitis based on the guidelines criteria of mucopurulent endocervical discharge and 10 or more PMN per high-power microscopic field had a sensitivity and specificity of 18.9% and 97.0% respectively, a positive predictive value of 29.2% and a positive likelihood ratio (LR) of 6.2 (p = 0.003). Presumptive diagnosis based on endocervical discharge with edema, erythema or induced mucosal bleeding of the cervix had a sensitivity and specificity of 43.2% and 80.0% respectively, a positive predictive value of 12.5% and a positive LR of 2.2 (p = 0.002). In the presence of bacterial vaginosis or vaginitis, the LR for the criteria of mucopurulent endocervical discharge and 10 or more PMN per high-power field was 5.4 (p = 0.04), whereas the LR was 4.3 (p = 0.10) if bacterial vaginosis and vaginitis were absent.

CONCLUSIONS

In this setting, the practice of making a presumptive diagnosis of chlamydial cervicitis on the basis of the criteria given in the Canadian STD guidelines was not supported.

FLAG epitope positioned in an external loop preserves normal biophysical properties of CFTR

We asked whether inclusion of the FLAG epitope in the fourth extracellular loop of the cystic fibrosis transmembrane conductance regulator (M2-901/CFTR), which permits detection of cell surface expression, affected CFTR's biophysical properties or channel regulation by kinases, phosphatases, and nucleotides. Channel activity of M2-901/CFTR was evaluated in numerous cell types and expression systems to characterize its gating and regulation. Our results show that M2-901/CFTR required adenosine 3',5'-cyclic monophosphate-dependent protein kinase phosphorylation to initiate channel activity. Subsequently, ATP alone was sufficient to support channel gating, and ADP inhibited channel opening. Current fluctuation analysis indicated that the nucleotide-dependent gating rates were indistinguishable from those of wild-type (wt) cystic fibrosis transmembrane conductance regulator (CFTR). Channel conductance in symmetric Cl- (11.2 pS), anion permeability ratio (1.66), and block by gluconate indicate that the anion conduction pathway is indistinguishable from wtCFTR. Sulfonylureas (glibenclamide and LY-295501) inhibited M2-901/ CFTR channel activity by an identical mechanism to that described for wtCFTR. Finally, CFTR-dependent insertion and retrieval of cell membrane was unaffected by the presence of the FLAG epitope. These results indicate that this structural alteration does not affect the control mechanisms for channel gating and suggest that the fourth extracellular loop of CFTR does not contribute to the ion pore. Detection of M2-901/CFTR by a commercially available monoclonal antibody (M2), together with presentation of normal functional properties, makes M2-901/CFTR a valuable tool to evaluate CFTR protein expression and cellular location.

Mouse germinal center B cells with the xid mutation retain responsiveness to antimouse CD40 antibodies but diminish IL-5 responsiveness

The germinal center (GC) develops in secondary lymphoid tissues in response to thymus-dependent (TD) antigens. To investigate the molecular mechanism of B cell differentiation in GC, we enriched GC B cells from spleen of TD antigen-immunized wild-type and X-linked immunodeficient (XID) mice, and examined the differentiation of GC B cells into antigen-specific IgG1 antibody-forming cells (AFC) in response to anti-CD40 mAb and cytokines. A significant proportion of freshly purified GC B cells expressed receptors for IL-4 and IL-5. Anti-CD40 mAb sustained the viability of GC B cells and IL-4 co-operated with anti-CD40 mAb for further enhancement of the cell viability. Anti-CD40 mAb and IL-4 were essential for inducing differentiation of GC B cells into antigen-specific IgG1-AFC and IL-5 efficiently enhanced their differentiation. GC B cells with the xid mutation responded for proliferation to CD40 ligation to a lesser extent and for the IgG1-AFC response to anti-CD40 mAb together with IL-4, but they showed impaired responsiveness to IL-5, regardless of enhanced expression of IL-5R in response to anti-CD40 mAb and IL-4. These results suggest that anti-CD40 mAb, IL-4 and IL-5 play a critical role in the differentiation of mouse GC B cells. The GC B cells from XID mice show a functional defect with respect to IL-5-mediated differentiation.