Canine Lymphomas: a Morphological and Immunohistochemical Study of 55 Cases, with Observations on p53 Immunoexpression

The purpose was to determine the immunophenotype of canine lymphomas (CLs) classified according to the WHO nomenclature for domestic animals, and to relate these findings to the immunoexpression of p53 protein. Lymphomas were immunophenotyped with antibodies to CD79a, CD3, and p53 protein, suitable for paraffin wax-embedded tissue sections. Of 55 cases, 40 (72.7%) were of the B-cell phenotype, 12 (21.8%) of the T-cell phenotype, and three (5.4%) were non-B-non-T lymphomas. Of the 40 B-cell lymphomas, 31 were of the large B-cell type, six were lymphoplasmacytic, one lymphocytic, one follicular (grade II) and one unclassified low-grade. One of the peripheral T-cell lymphomas was morphologically consistent with anaplastic large cell lymphoma. Immunolabelling for p53 occurred in 24 B-cell and seven T-cell lymphomas. Lymphomas with high grade histology showed a significantly increased frequency of p53 positivity (P = 0.01). Positivity for p53 (more than 10% positive cells) tended to be associated with the T-cell phenotype (P = 0.06). Mean patient age was significantly higher in p53-positive cases (P = 0.02). These data are comparable with findings in human lymphomas.

Gallium scan in adolescents and children with Hodgkin's disease (HD). Treatment response assessment and prognostic value

AIM

The aim of the present paper is to describe the accuracy of gallium ((67)Ga) scintigraphy in adolescents and children with Hodgkin's disease (HD). We have studied the diagnostic value of this nuclear imaging technique at disease presentation (staging) and its prognostic value based on changes in (67)Ga uptake observed after treatment (response assessment).

METHODS

From April 1985 to July 1999 74 consecutive untreated patients with a median age of 13 y underwent (67)Ga scans 48-72 h after injection of 37-111 MBq of (67)Ga-citrate. Planar whole-body scintigraphy was performed, supplemented with single photon emission tomography (SPET) of the mediastinum from 1996 onwards. Three patients did not undergo further scintigraphic examination because they were treated with radical surgery. After the 1st examination 71 of the 74 patients were monitored by 1-3 (67)Ga scans during the course of their disease. All of them had at least one (67)Ga scintigraphy at the end of the induction phase of chemotherapy, before any other therapeutic regimens were planned.

RESULTS

At disease presentation (67)Ga scintigraphy was positive in all patients, detecting 285 of 335 (85.0%) lymph nodal sites of disease. The best sensitivity was observed in the mediastinum (100%; 63/63) and the laterocervical supraclavicular region (85.6%; 125/146); it was lower for axillary (72.7%; 16/22) and retroperitoneal (68.7%; 11/16) lymph node masses. In detecting visceral involvement the sensitivity of (67)Ga scintigraphy was 66.6% (8/12) for lung and 80% (4/5) for bone involvement. Among 71 patients in follow-up, 2 showed rapid progression of disease during induction therapy while 69 patients were monitored for a long period. The response to therapy has been classified according to the changes observed on nuclear medicine or radiological images as complete response (CR) or partial response (PR). On the basis of (67)Ga scans 55 patients (72.4%) were considered as having a CR, while with radiological modalities (chest X-ray, CT, MRI) CR was observed in only 29 patients (40.8%). PR or progression was found with (67)Ga scintigraphy in 16 patients (22.5%) and with radiological modalities in 42 patients (59.1%). (67)Ga scan was concordant with clinical outcome in 97% (28/29). The diagnostic effectiveness of this imaging technique has been analysed by comparing the scintigraphic or radiological changes at the 1st scintigraphic/radiological follow-up examination after induction therapy with the clinical outcome. In this population the relapse rate was 50% (8/16) in the group that did not achieve a CR according to post-treatment (67)Ga scintigraphy, while it was only 10.9% (6/55) in the group that achieved a CR on the basis of scintigraphy findings. The overall survival (OS) and disease-free survival (DFS) were calculated by means of Kaplan-Meier cumulative survival plotting. When the 2 groups of patients with complete (CR) or incomplete normalisation (PR or progression) of (67)Ga scintigraphy were compared, both OS and DFS were found to be statistically different (p=0.0001 and p=0.0004, respectively). By contrast, no statistical difference was found when the radiological findings were considered as the criterion for assessment of tumour response. On the basis of X-ray results the relapse rate was 13.7% in patients with negative post-therapy findings and 23.8% in patients with positive radiological imaging.

CONCLUSION

Our data demonstrate the high value of (67)Ga scintigraphy in HD staging in paediatric patients. In addition, evaluation of the (67)Ga uptake is very useful as a prognostic parameter; changes in (67)Ga uptake after therapy indicate a favourable prognosis, whereas children still positive on post-treatment (67)Ga scintigrams should be given more aggressive treatment.

Experimental Trypanosoma evansi infection in South American coati (Nasua nasua): hematological, biochemical and histopathological changes

The course of an experimental Trypanosoma evansi infection in coatis (Nasua nasua, carnivora, Procyonidae) was followed for 262 days. Hematological analysis of the infected coatis revealed a marked decline in hemoglobin, packed-cell volume, and total erythrocyte count. An intense anemia followed the first wave of parasitemia and persisted until the end of the experimental period. Biochemical analysis showed increased serum levels of alanine aminotransferase and aspartate aminotransferase and decreased albumin. The main histopathological features consisted of myocarditis with the presence of degenerate cardiac fibers and meningoencephalitis. This study has shown that coatis infected with T. evansi develop a chronic disease.

Fibroelastoma of the mitral valve as a cause of transient ischemic stroke

A 44-year-old woman had a transient ischemic stroke, fibroelastoma of the mitral valve being the source of the embolus. The patient evolved with neutropenia induced by ticlopidine after 10 days of treatment. We report the major clinical features, therapeutical options, and medicamentous toxicity resulting from the use of antiplatelet drugs.

Post-stress end-systolic left ventricular dilation: a marker of endocardial post-ischemic stunning

Several studies have shown the accuracy of gated single photon emission computed tomography (SPECT) using thallium-201 and technetium tracers in the assessment of myocardial perfusion and function. Gated SPECT has been successfully utilized to detect post-stress left ventricular ejection fraction (LVEF) reduction resulting from post-ischemic stunning in patients with coronary obstruction. The aim of this study was to evaluate whether the post-stress LVEF impairment could be related to the post-stress end-systolic ventricular dilation resulting from post-ischemic endocardial stunning. Two hundred and eighty-two consecutive patients were studied by conventional diagnostic 2 day stress/rest gated SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual-headed SPECT camera. One hundred and forty-seven of these patients (52%) showed reversible perfusion defects, 69 (24%) permanent defects and the remaining 66 (24%) had normal perfusion. One hundred and thirty-eight of these patients had a history of myocardial infarction (MI) and 19% underwent coronary angiography without an intervening cardiac event. Perfusion was analysed on ungated images using 20 segments scored on a five-point scale (0, normal; 4, no uptake), while wall thickening (WT) was assessed visually on stress/rest end-systolic images using a four-point score (0, normal; 3, absence of WT). LVEF and volumes were calculated using an automatic algorithm. The post-stress and rest ratios were determined for both end-diastolic (EDV) and end-systolic (ESV) volume. Normal values for all these parameters were obtained using data from 149 patients with a low likelihood (<5%) of coronary artery disease (CAD). In 50 of the 147 (34%) of patients with reversible perfusion defects, post-stress LVEF was >5% lower than rest values (stunned group), while the remaining 97 patients did not show a significant LVEF change (group 2A). The percentage of patients who developed exercise-induced angina, the percentage of patients who underwent coronary angiography and the segmental summed perfusion and WT scores were significantly higher in the stunned group compared with group 2A. Only ESV increased significantly post-stress, and this increase occurred only in stunned patients. Both EDV and ESV ratios were significantly higher in the stunned group compared with normal controls (P=0.008 and P<0.000001, respectively) and with the subgroup 2A (P=0.011 and P<10(-12), respectively). The ESV stress/rest ratio correlated significantly with the summed WT difference score by univariate analysis in stunned patients. It can be concluded that the post-stress ESV dilation, obtained by stress/rest gated SPECT, seems to be due to endocardial post-ischemic stunning. The stunned patients showed more severe clinical, angiographic, perfusion and function parameters.

[Detection and assessment of myocardial stunning with perfusion tomographic scintigraphy using gated SPECT]

BACKGROUND

Gated-SPECT using 99mTc-labeled flow tracers provides the simultaneous assessment of global and regional myocardial perfusion and function. The aim of this study was to identify patients with stress-induced postischemic stunning, among those with reversible stress perfusion defects, and patients with artifactual defects among those with fixed defects, in order to assess the value of the functional data provided by gated acquisition of perfusion imaging in the characterization of ischemia.

METHODS

We studied 221 consecutive patients who underwent conventional diagnostic dual day stress/rest gated-SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual head SPECT camera, 115 of whom (52%) showed reversible perfusion defects, and 66 (30%) fixed defects. Perfusion was analyzed on ungated images using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake), while wall thickening was assessed visually on stress/rest end-systolic images using a 4-point score (0 = normal, 3 = absence of wall thickening). Left ventricular ejection fraction and volumes were calculated using an automatic algorithm (quantitative gated-SPECT). Fifty-two out of 221 (23.5%) patients underwent coronary angiography.

RESULTS

In 40/115 (35%) patients with reversible perfusion defects, post-stress left ventricular ejection fraction was > 5% lower than that at rest (Group A: stunned), whereas in the remaining 75 patients, post-stress left ventricular ejection fraction was either +/- 5% or greater than that at rest (Group B: non-stunned). Peak exercise angina and ischemic electrocardiographic response to exercise were present in 79 and 58% respectively of Group A patients and in 33 and 39% of Group B patients. The number of patients with multivessel disease was significantly higher in Group A compared to Group B (58 vs 41%, p < 0.05). The total stress and rest perfusion scores were significantly higher in Group A than in Group B (p < 0.01); even the total stress wall thickening score was significantly higher in Group A (p < 0.001). As for global parameters, post-stress end-systolic volume was significantly higher in the stunned group (p < 0.05). In 40 out of 66 (60.5%) patients without reversible ischemia fixed defects were judged to be ischemic (Group C), while in 26/66 (39.5%) they were attributed to attenuation artifacts (Group D). Eighty percent of Group C patients had a previous myocardial infarction against none of Group D. Stress/rest perfusion and wall thickening scores were significantly higher in Group C than in Group D.

CONCLUSIONS

Gated-SPECT myocardial perfusion evaluation allowed us to identify a subgroup of post-stress stunned coronary artery diseased patients. The post-stress left ventricular ejection fraction reduction in this population seems to be due to the increase in end-systolic volume. The stunned patients showed more severe perfusion defects and wall thickening abnormalities.

Clinical, parasitological and immunological aspects of experimental infection with Trypanosoma evansi in dogs

This research investigated the pattern of antibody response by means of enzyme linked immunosorbent assay (Elisa) and indirect fluorescent antibody test (IFAT) through the course of experimental Trypanosoma evansi infection in dogs. Clinical and parasitological features were also studied. The average prepatent period was 11.2 days and parasitaemia showed an undulating course. Biometrical study of parasites revealed a mean total length of 21.68mm. The disease was characterized by intermittent fever closely related to the degree of parasitaemia and main clinical signs consisted of pallor of mucous membrane, edema, progressive emaciation and enlargement of palpable lymph nodes. Diagnostic antibody was detected within 12 to 15 days and 15 to 19 days of infection by IFAT and Elisa, respectively. High and persistent antibody levels were detected by both tests and appeared not to correlate with control of parasitaemia

Isolation of Babesia bigemina and babesia bovis merozoites by ammonium chloride lysis of infected erythrocytes

1. We describe the isolation of viable merozoites from erythrocytes infected with Babesia bovis or Babesia bigemina organisms by ammonium chloride lysis. 2. Parasite morphology was examined by both light and transmission electron microscopy. Erythrocyte-free parasites maintain their viability and infectivity, retain their antigenicity and are suitable for use in the indirect fluorescent antibody assay.

Toxicologic evaluation of acute and subacute oral administration of Cucurbita maxima seed extracts to rats and swine

The extract prepared from dried seeds of Cucurbita maxima was administered to rats and pigs. Following a single dose or 4 weeks of daily oral administration, the extract produced no changes in serum glucose, urea, creatinine, total protein, uric acid, GOT, GPT, LDH or blood counts. Urine analysis (urea, uric acid, creatinine, total protein, Na and K), as well as histopathological investigation, showed no abnormalities. These results taken as a whole indicate that the seeds of C. maxima as used in Brazilian folk medicine are not toxic for rats and swine.

[4 cases of Horton's temporal arteritis. Hypothesis on the possible correlations with rheumatic polymyalgia]

Giant cell arteritis (GCA) or temporal arteritis is an entity of unknown aetiology and uncertain autonomy for the close relationship with polymyalgia rheumatica (PMR). This work describes four patients with GCA alone. All patients had clinical and laboratoristic evidence of the disease and were treated with steroids. The distribution of HLA antigens showed an increased occurrence of DR4 and B8 antigens. Unfortunately, the small number of patients and the short period of observation don't allow to prove the exact nature of the link between GCA and PMR.

Human pulmonary dirofilariasis: report of a new European case

We report a new European case of pulmonary dirofilariasis occurring in an Italian patient. The paper emphasizes the peculiar pathological features of Pulmonary Dirofilariasis, that, on clinical and radiological grounds, closely imitates primary or secondary neoplasms. The disease characteristically presents itself as a solitary subpleural coin-like lesion, histologically corresponding to a well demarcated, roughly spherical infarct, centered by a medium-sized thrombosed artery whose lumen contains the parasite, i.e. a Dirofilaria nematode.

Analysis of the B-cell growth-promoting activity of human IL-4, the co-stimulatory assay with anti-immunoglobulin antibodies. Comparison with the B-cell growth-promoting activity of other lymphokines

Human recombinant interleukin-4 (rIL-4) was assessed for its ability to promote the proliferative response of purified human B cells co-stimulated with submitogenic concentrations of soluble F(ab')2 fragments of anti-immunoglobulin (Ig) antibodies. The growth-promoting activity of rIL-4 was usually as potent as, or even more potent than, that of recombinant interleukin-2 (rIL-2), and more potent than that of recombinant interferon-gamma (rIFN-gamma). Preincubation with rIL-4 did not cause enhancement of the proliferative response of B cells to the subsequent addition of rIL-4 and anti-IgM antibody. In contrast, the proliferative response of B cells preincubated with anti-IgM antibody and rIL-4 was potentiated by the subsequent addition of rIL-4. The simultaneous addition of rIFN-gamma and rIL-2 or rIFN-gamma and rIL-4 had an additive effect in comparison with the response induced by rIL-2 or rIL-4 alone, respectively, whereas simultaneous addition of rIL-2 and rIL-4 induced a response equal or lower than that stimulated by rIL-2 or rIL-4 alone. The addition of rIFN-gamma at the beginning of culture or preincubation of B cells with rIFN-gamma and anti-IgM antibody potentiated the proliferative response of B cells to the subsequent addition of either rIL-2 or rIL-4. Taken together, these data suggest that rIL-4 acts as a growth factor for activated human B cells and displays on such cells a growth-promoting activity similar to that of rIL-2.

The Fc epsilon R2/CD23 antigen: a hallmark of chronic lymphocytic leukemia B cells

The effect of different stimuli on the expression of the low-affinity receptor for the Fc fragment of IgE (Fc epsilon R2/CD23) on peripheral blood B cells from patients with chronic lymphocytic leukemia (CLL) was investigated. CLL B cells cultured for 3 days in medium alone showed a progressive decrease of the Fc epsilon R2/CD23 expression, while the addition to the cell cultures of IgE or interleukin-4 had a slackening effect on the decrease of the Fc epsilon R2/CD23. In contrast, in the presence of interferon-gamma the proportion of Fc epsilon R2/CD23+ cells was more rapidly reduced compared to CLL B cells cultured in medium alone. Stimulation of CLL B cells with Staphylococcus aureus Cowan I (SAC) bacteria, which are able to enhance the expression of Fc epsilon R2/CD23 on normal B cells, induced a rapid loss of the Fc epsilon R2/CD23 from CLL B cells.

Role of HLA class I and class II antigens in activation and differentiation of B cells

The monoclonal antibodies (MoAb) CR10-214, CR11-115, and Q1/28 to distinct monomorphic determinants of HLA class I antigens, the MoAb CL413 and PTF29.12 recognizing monomorphic determinants of HLA-DR antigens, the anti-HLA-DQw1 MoAb KS11, the anti-HLA-DPw1 MoAb B7/21, and the anti-HLA-DR,DP MoAb CR11-462 were tested for their ability to modulate human B-lymphocyte proliferation and maturation to IgM-forming cells. Purified tonsillar B cells were stimulated with Staphylococcus aureus bacteria of the Cowan first strain (SAC) or anti-human mu-chain xenoantibodies, as well as in growth factor- or T-cell-dependent activation cultures. The B-cell proliferative responses induced by SAC or by mitogenic concentrations of anti-mu-chain xenoantibodies were inhibited by some of the anti-HLA class I and anti-HLA class II monoclonal antibodies tested. The same antibodies were effective inhibitors of the proliferation of B cells stimulated with interferon-gamma (IFN-gamma) or interleukin-2 (IL-2) and with submitogenic concentrations of anti-mu-chain xenoantibodies. The proliferation induced by IL-2 of SAC-preactivated B cells was inhibited by some of the anti-HLA class II monoclonal antibodies, but not by the anti-HLA class I monoclonal antibodies tested. This inhibition appeared to reflect at least in part a direct effect on later events of the B-cell activation cascade, since some anti-HLA class II monoclonal antibodies still exerted considerable inhibitory activity when added together with IL-2 to SAC-preactivated B cells after the third day of culture. Anti HLA-DR, DQ, and DP monoclonal antibodies consistently inhibited the IgM production induced in B cells by T cells alone, T cells plus pokeweed mitogen (PWM), SAC plus IL-2, or IL-2 alone. In contrast, two of the three anti-HLA class I monoclonal antibodies tested inhibited the IgM production in cultures stimulated with SAC plus IL-2 and one the IgM production induced by IL-2 alone, but none of them had inhibitory effects on T-cell dependent IgM production. The results reported herein indicate that HLA class II molecules directly participate in different phases of the B-cell activation cascade. In addition, our data also suggest that HLA class I molecules can be involved in the events leading to B-cell proliferation and differentiation into immunoglobulin-secreting cells.

Analysis of the role of interferon-gamma, interleukin 2 and a third factor distinct from interferon-gamma and interleukin 2 in human B cell proliferation. Evidence that they act at different times after B cell activation

Recombinant interferon-gamma (rIFN-gamma) was able to induce proliferation of human tonsillar B cells activated with suboptimal concentrations of anti-mu antibody. The B cell growth factor (BCGF) activity of rIFN-gamma was not due to substances contaminating the IFN-gamma preparation, nor was it mediated by factors released by T cells or large granular lymphocytes following activation by rIFN-gamma. The response of B cells to rIFN-gamma peaked on day 3 of culture and rapidly declined thereafter, whereas the response of parallel anti-mu-activated B cell cultures to recombinant interleukin 2 (rIL2) appeared on day 3, but continued at least until day 5. In addition, B cells responsive to rIFN-gamma could be at least in part separated from those responsive to rIL2, the former being primarily contained in B cell fractions enriched for high-density small B lymphocytes. Finally, the addition to anti-mu-stimulated B cell cultures of very low concentrations of rIFN-gamma potentiated the B cell proliferation promoted by rIL2. The simultaneous addition of monoclonal antibodies against IFN-gamma and T cell activation antigen to anti-mu-stimulated B cell cultures strongly reduced the B cell proliferative response promoted by three different crude BCGF preparations obtained by polyclonal T cell activation in mixed lymphocyte culture. However, the supernatant from a T cell clone (DP5/11) apparently free of IL2, which manifested a BCGF activity similar to that of rIFN-gamma, still maintained its ability to promote proliferation of anti-mu-activated B cells after complete removal of IFN-gamma. Taken together, our data indicate that although some T cell clones are able to produce a BCGF distinct from both IFN-gamma and IL2, these lymphokines account for most of the BCGF activity of supernatants obtained from polyclonal T cell populations. They also suggest that IFN-gamma and the BCGF distinct from IFN-gamma and IL2 act primarily in the earlier phases of B cell activation and potentiate the proliferative response of activated B cells to IL2.

Direct induction of human B-cell differentiation by recombinant interleukin-2

Recombinant interleukin-2 (rIL-2) induced highly purified human tonsillar B cells to differentiate into immunoglobulin (Ig)-producing cells in vitro. The B-cell response was not due to rIL-2-contaminating substances, but reflected the activity of IL-2 itself, since it was inhibited by addition to the cultures of anti-TAC monoclonal antibody. The rIL-2-induced B-cell response was apparently not mediated by factors released by residual T cells present in B-cell suspensions at undetectable levels, since supernatants (SN) from unstimulated autologous T cells cultured at concentrations even much higher than those possibly contaminating B-cell suspensions did not induce any detectable Ig production. In addition, the Ig production by B cells cultured with SN prepared from high numbers of autologous T cells stimulated with rIL-2, as well as from allo-activated or mitogen-stimulated T cells, was of the same magnitude as the Ig production resulting from direct addition of rIL-2 concentrations comparable with those present in the supernatants. After centrifugation on Percoll density gradients, most of the tonsillar B cells responsive to rIL-2 were recovered in the lower density cell fraction containing a number of larger activated B cells. Moreover, B-cell enriched suspensions from peripheral blood (PB) (which usually contains a lower number of in vivo activated B cells than tonsil) showed poor or no response to rIL-2 alone, but displayed significant Ig production when rIL-2 was added to the cultures in the presence of Staphylococcus aureus Cowan I (SAC) bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

HTLV-III seropositivity in symptom-free Italian haemophiliacs. Correlation with consumption of commercial concentrate and abnormalities of T and B lymphocytes

Various immunological parameters exploring both T- and B-cell functions were determined in a group of 74 symptom-free Italian haemophiliacs treated with commercial concentrate imported from the USA and were correlated with the presence in their serum of antibody to HTLV-III. There was a strong correlation between HTLV-III seropositivity and the amount of concentrate consumed. A significant correlation between HTLV-III seropositivity and T-cell alterations, such as T4/T8 ratio less than 1 and reduction in the absolute number of T4+ lymphocytes, or B-cell alterations such as hypergammaglobulinaemia and enhanced spontaneous IgG synthesis in vitro, was also observed.

Abnormalities of in vitro immunoglobulin production in apparently healthy haemophiliacs: relationship with alterations of T cell subsets and with HTLV-III seropositivity

The pokeweed mitogen (PWM)-induced immunoglobulin (Ig) production by cultures of peripheral blood mononuclear cells (PBMC) was reduced in healthy haemophiliacs treated with commercial factor VIII (or IX) concentrate, whereas the spontaneous IgG synthesis in vitro was enhanced. PWM-induced Ig production was lower in those who had received greater amounts of concentrate, in those with inverted T4/T8 lymphocyte ratios and in those with antibody to HTLV-III. The spontaneous IgG production in vitro was higher in haemophiliacs who had received larger amounts of concentrate, in those with inverted T4/T8 ratio and in those with antibody anti-HTLV-III. However, some patients with normal T4/T8 ratio and some with HTLV-III antibody also had raised spontaneous IgG production.

Synergy of B cell growth factor and interleukin 2 in the proliferation of activated human B cells

The activity of purified interleukin 2 (IL2), obtained by the recombinant DNA technology, on the proliferative response of human B cells stimulated with low concentrations of anti-mu antibody was investigated. Recombinant IL2 was capable of augmenting the proliferative response of anti-mu-activated B cells and the T cell activation (Tac) antigen was expressed on a substantial proportion of normal B cells stimulated with anti-mu antibody. However, crude supernatants from protein A-stimulated peripheral blood mononuclear cells, which were found to possess both IL2 and B cell growth factor (BCGF) activities, maintained the ability to promote proliferation of anti-mu-activated B cells after depletion of IL2. In addition, supernatants from some T cell clones, apparently free of IL2 activity, displayed strong BCGF activity in the co-stimulation assay with anti-mu antibody. This BCGF activity was found in 25 kDa fractions by gel filtration and it was unaffected by addition to the cultures of anti-Tac antibody, which consistently inhibited the B cell proliferative response promoted by recombinant IL2. The proliferative response of anti-mu-activated B cells to clonal, IL2-free supernatants containing BCGF and recombinant IL2 present together from the beginning of culture was close to the sum of responses to the two stimulants, separately. In addition, the presence of clonal supernatant containing BCGF from the beginning of culture had a synergistic effect in the response of activated B cells to the subsequent addition of IL2, whereas the initial presence of IL2 had no such an effect on the reactivity of anti-mu-stimulated B cells to the late addition of clonal supernatant containing BCGF. The synergistic effect of BCGF in the IL2-promoted B cell proliferation was probably the result of the recruitment of a greater number of IL2-reactive B cells. In fact, the number of Tac-positive cells was significantly higher in 36-h cultures established in the presence of anti-mu antibody plus clonal supernatant containing BCGF than in cultures stimulated with anti-mu antibody alone. Taken together, these data indicate that anti-mu antibody promotes the expression by normal human B cells of distinct receptors for IL2 and a BCGF distinct from IL2. They also suggest that BCGF can exert a synergistic effect in the IL2-promoted proliferation of activated B cells.

Different reactivity of activated human B cells to B-cell growth factor and interleukin 2 in the costimulation assay with anti-IgM antibody and in the preactivation assay with Staphylococcus bacteria

The two main assay systems which have been developed for the study of lymphokine-mediated human B-cell proliferation, i.e., the costimulation assay with anti-mu antibody and the preactivation assay with Staphylococcus aureus Cowan I (SAC) bacteria, were compared. Purified interleukin 2 (IL-2), obtained by the recombinant DNA technology (r-IL-2), enhanced the proliferative response of anti-mu-stimulated human B cells in the costimulation assay with anti-mu antibody and maintained the B-cell proliferation induced by preactivation with SAC bacteria. Although the majority of T-cell clones, established from normal peripheral blood T lymphocytes, showed production of both IL-2 and B-cell growth factor (BCGF) following phytohemagglutinin (PHA)-stimulation, some T-cell clones were found whose supernatants (PHA-SN), apparently free of IL-2, manifested strong BCGF activity in the costimulation assay with anti-mu antibody. However, the same clonal, IL-2-free, T-cell SN displayed no BCGF activity in the preactivation assay with SAC bacteria. When B cells were activated for 3 days with anti-mu antibody, followed by the addition of r-IL-2 or clonal T-cell SN containing BCGF for an additional 3 days, r-IL-2 showed the ability to maintain B-cell proliferation, whereas clonal SN containing BCGF had virtually no effect. These data indicate that the costimulation assay with anti-mu antibody explores the reactivity of normal human B cells to both BCGF and IL-2, whereas the preactivation assay with SAC bacteria, due to a shorter reactivity to BCGF of activated human B cells, essentially represents a probe for the study of IL-2-promoted B-cell proliferation.

Role of class II histocompatibility antigens in Staphylococcus aureus protein A-induced activation of human T lymphocytes

The capacity of peripheral blood monocytes and B lymphocytes to support staphylococcal protein A (SpA)-induced proliferation of autologous and allogeneic T cells, as well as the role of major histocompatibility complex (MHC) class I and II molecules in this activation process, were investigated. Highly purified peripheral T lymphocytes did not proliferate in response to SpA, but their response was reconstituted by both irradiated (or mitomycin C-treated) monocytes and B lymphocytes. The effect of B cells on the SpA-induced T-cell response could not be explained by a contamination of residual accessory cells because long-term continuous B-cell lines restored SpA-induced T-cell DNA synthesis as effectively as did monocytes. Support of SpA responsiveness by B cells could not be accounted for by polyclonal binding of SpA to cell surface immunoglobulins, since the ability of SpA-unreactive and SpA-reactive B cells was comparable. The cells from two human leukemic lines--K562 and Raji--showed the same ability in supporting the pokeweed mitogen-induced T-cell response, but the class II-positive Raji cells were much more effective than class II-negative K562 cells in restoring the T-cell responsiveness to SpA. Monoclonal antibodies specific for monomorphic determinants of MHC class II antigens, as well as their F(ab')2 fragments, consistently inhibited the SpA-induced proliferative response, whereas antibodies specific for MHC class I antigens were without effect. The antibodies specific for class II antigens appeared to act at the level of accessory cell, since pretreatment with these antibodies inhibited the ability of SpA-pulsed monocytes or Raji cells to present SpA to autologous or allogeneic T lymphocytes, respectively. These data indicate that either monocytes or normal and lymphoblastoid B cells can act as accessory cells for the proliferative response of human T cells to soluble SpA and that monomorphic determinants of MHC class II molecules play an important role in this activation process.

Anti-Ia reactivity in sera of untreated patients with active Hodgkin's disease

The effect of sera from eight patients with Hodgkin's disease on the autologous and allogeneic mixed lymphocyte response of normal individuals was examined. Sera from three patients with active disease caused marked inhibition of both autologous and allogeneic mixed lymphocyte reaction without inducing significant reduction of the phytohemagglutinin-induced proliferative response. The inhibitory activity of Hodgkin's disease sera on the autologous mixed lymphocyte reaction was removed by adsorption with non-T, but not T, lymphocytes and it was correlated with the ability of such sera to block the binding of monoclonal anti-Ia antibody to Ia-positive target cells. Anti-Ia antibodies were detected in the same sera by double antibody radioimmunoassay and analysis on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, using 125I-labeled, partially purified, Ia antigens from two different human B-cell lines. This anti-Ia reactivity was strongly reduced or absent in sera taken from the same patients at the completion of multidrug chemotherapy.

Alterations of both responder T cells and stimulator non-T cells are responsible for abnormal mixed lymphocyte reaction in aged humans

The autologous and allogeneic mixed lymphocyte reactions of 15 young and 15 aged human adults were compared. Both autologous and allogeneic mixed lymphocyte reactions were significantly reduced in the aged group. T cells from aged adults displayed a reduced proliferative response to non-T cells of either aged or young adults. T cells from young adults also showed a reduced proliferative response to non-T cells from aged adults. Sera from aged adults, showing depression of autologous and allogeneic mixed lymphocyte reaction, did not exert any inhibitory effect on the autologous and allogeneic mixed reaction of lymphocytes from young donors. These data suggest that depression of mixed lymphocyte reaction in aged humans probably reflects intrinsic abnormalities of both responder T cells and stimulatory non-T cells.