Coombs-negative severe haemolytic anaemia in an immunocompetent adult following cytomegalovirus infection.

Severe haemolysis is a rare, but potentially life-threatening, complication of cytomegalovirus (CMV) infection in immunocompetent adults. Treatment with steroids or immunoglobulins, or even splenectomy, may be justified when an autoimmune mechanism can be identified as the cause of the anaemia. Described here is the case of a previously healthy patient who presented with severe haemolytic anaemia following CMV infection. The patient's haemoglobin level fell to 5.1 g/dl while extensive testing for an autoimmune mechanism remained negative. The patient made a slow but full recovery without additional medication or blood transfusions. This case demonstrates that severe haemolytic anaemia following CMV infection is possible even when presently available tests fail to show autoimmune positivity. In immunocompetent subjects a wait and see policy, with supportive care when necessary, is likely to be justified.

Monocyte activation in peripheral blood and dialyser eluates: phenotypic profile and cytokine release.

BACKGROUND/AIMS: Monocyte activation and subsequent cytokine generation is presumed to be involved in haemodialysis (HD)-related morbidity. The present study was designed to investigate HD-induced changes in monocytes, with respect to their phenotypic profile and cytokine release, both in peripheral blood (PB) and dialyser eluates (DE). In addition, the effect of the type of dialyser on monocyte activation was assessed. METHODS: Dialyser elution was performed in 8 patients after 3 h of HD, using cuprammonium (CU) and polysulfon (PS) dialysers in a randomised cross-over design. PB samples and DE were analysed for both the expression of a variety of monocyte cell surface markers (CD62L, CD11b, CD25, HLA-DR, CD64 and CD14) by flow cytometry and IL-1beta levels. Monocytes were identified by dual labelling with antibodies against CD14. RESULTS: In PB, the expression of CD11b increased during HD with both devices, but was more pronounced with CU (CU versus PS: p < 0.05). CD62L decreased during HD, but only significantly for PS (p < 0.02). HLA-DR was downregulated during HD with CU (p = 0.056). The expression of CD64 was higher during HD with CU (p = 0.02). Finally, CD14 increased during HD with both dialysers (p < 0.03). DE yielded a mean cell count of 51 x 10(6) cells. The proportion of monocytes in DE was 3% for CU and 4% for PS. In eluted monocytes, a significant upregulation of CD11b, CD25, and HLA-DR was observed. CD62L was downregulated when compared to PB at t(180) (p < 0.001). In DE, no correlation was found between the type of dialyser and the phenotypic changes. In 10 of 16 DE supernatants, 6 CU and 4 PS, IL-1beta release could be demonstrated, CU yielding significantly more of this cytokine than PS (p = 0.03). CONCLUSIONS: According to both their phenotypic profile and cytokine release, monocytes sticking to the dialyser membrane after HD are considerably more activated than circulating monocytes. Activation of eluted monocytes appeared independent of the type of dialyser, suggesting an effect of mechanical stress rather than bioincompatibility. In contrast, phenotypic activation of peripheral blood monocytes and cytokine release in the DE supernatant were mainly dialyser-dependent.

Hemodialysis-induced degranulation of polymorphonuclear cells: no correlation between membrane markers and degranulation products.

BACKGROUND/AIMS: Degranulation of polymorphonuclear leukocytes (PMN) during hemodialysis (HD) is usually assessed by measuring degranulation products. However, this process might also be estimated by the assessment of cell surface markers. In this study, the relationship between the expression of PMN degranulation markers (CD63 and CD66b) and the release of degranulation products [myeloperoxidase (MPO) and lactoferrin (LF)] was investigated during clinical HD in order to evaluate cell surface markers as a useful index of PMN degranulation. METHODS: The expression of CD63 and CD66b on PMN and the release of MPO and LF were investigated in 10 chronic HD patients, during both heparin (HDhep) and trisodium citrate anticoagulation (HDcit), in a randomized order. Samples were drawn from both the efferent and afferent lines of the dialyzer at 0, 7.5, and 180 min. RESULTS: During HDhep at first passage, a major increase in MPO (from 158 +/- 32 to 448 +/- 177 microg/l, p = 0.001) and LF (from 134 +/- 52 to 260 +/- 120 microg/l, p = 0.01) was found across the dialyzer, whereas marked changes were not observed during HDcit. The expression of CD63 and CD66b increased across the dialyzer during both anticoagulation modalities, but was only significant in the case of HDhep (CD63: mean fluorescence intensity from 247 +/- 61 to 331 +/- 118, p < 0.01; CD66b: mean fluorescence intensity from 340 +/- 76 to 434 +/- 103, p = 0.01). During HDhep a correlation was noted between the degranulation products and markers of both azurophilic and specific granules (MPO and CD63: r = 0.35; p < 0.01; LF and CD66b: r = 0.39, p < 0.01). Significant differences in the expression of CD63 and CD66b between HDhep and HDcit were not observed. When analyzing the combined data for both HDhep and HDcit, no correlation was observed between degranulation products and markers. CONCLUSION: Our data suggest that the measurements of cell surface markers may not be a reliable indicator of the degree of HD-induced PMN degranulation.

Effects of dialyser and dialysate on the acute phase reaction in clinical bicarbonate dialysis.

BACKGROUND: In chronic haemodialysis (HD), morbidity may result from repetitive induction of the acute phase response, caused by a bioincompatible dialysis membrane and/or contaminated dialysate. In the present study, cytokine release (interleukin-6, IL-6) and subsequent production of acute phase proteins (C-reactive protein, CRP and secretory phospholipase A(2), sPLA(2)) were assessed to investigate whether the HD-induced acute phase reaction depends mainly on the type of membrane or on the sterility of the dialysate. METHODS: In 11 patients, IL-6, CRP and sPLA(2) levels were assessed in blood samples drawn before (t(0)), at the end (t(180)) and 24 h after the start of HD (t(1440)). All patients were dialysed on Cuprammonium (CU) and Polysulphon (PS) dialysers and seven patients underwent an additional HD session on CU plus a dialysate filter (CUf). RESULTS: IL-6 levels were increased significantly at t(180) compared with t(0) (P<0.02) with both CU and CUf. At t(1440), IL-6 levels had returned to baseline. In contrast, marked fluctuations did not occur during HD with PS. At t(180), IL-6 was significantly greater with CU and CUf devices, than with PS (P<0.02). Following HD with CU and CUf, a significant increase in CRP was observed at t(1440), compared with postdialysis values (P

Clinical and immunological evaluation of patients with mild IgG1 deficiency.

Serum IgG subclass concentrations were determined in patients visiting, the pulmonology out-patient clinic with chronic respiratory tract problems. A total of 24 patients with a serum IgG1 concentration < 4.9 g/l (i.e. below the reference range) and normal values for IgG2, IgM and IgA were included. Patients with a selective IgG1 deficiency were vaccinated with a 23-valent pneumococcal polysaccharide vaccine. There were nine patients with a poor antibody response to pneumococcal capsular polysaccharide antigens. Responsiveness to protein antigens was intact in all patients. Patients with pneumonia showed a significantly lower anti-polysaccharide response in the IgG2 subclass than patients without pneumonia. Patients with recurrent sinusitis showed a significantly lower response in the IgA isotype after vaccination with pneumococcal polysaccharide vaccine compared with non-sinusitis patients. It can be concluded that patients with recurrent sinopulmonary infections and a mild IgG1 subclass deficiency have an impaired IgG1 anti-polysaccharide response, which can extend to decreased IgG2 and IgA anti-polysaccharide responses.

Cytokine profiles during clinical high-flux dialysis: no evidence for cytokine generation by circulating monocytes.

Secretion of cytokines by monocytes has been implicated in the pathogenesis of dialysis-related morbidity. Cytokine generation is presumed to take place in two steps: induction of mRNA transcription for cytokines by C5a and direct membrane contact, followed by lipopolysaccharide (LPS)-induced translation of mRNA (priming/second signal theory, Kidney Int 37: 85-93, 1990). However, the in vitro conditions on which this theory was based differed markedly from clinical dialysis. To test this postulate for routine hemodialysis, 13 patients were studied cross-over with high-flux cuprammonium (CU), cellulose triacetate (CTA), and polysulfon dialyzers, using standard bicarbonate dialysate, as well as CTA with filtered dialysate (fCTA). Besides leukocytes, C3a, C5a, and limulus amebocyte lysate reactivity, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6, IL-1RA, soluble TNF receptors, and IL-1 beta mRNA were assessed. Only during dialysis with CU did C5a increase significantly (561 to 8185 ng/ml, P < 0.001). Endotoxin content of standard bicarbonate was higher than filtered dialysate (median, 24.3 and < 5 pg/ml respectively, P = 0.002), whereas limulus amebocyte lysate reactivity was not detected in the blood, except in the case of CU. TNF-alpha levels were elevated before, and remained stable during, dialysis, independent of the modality used. IL-1 beta, IL-6, and mRNA coding for IL-1 beta could not be demonstrated. IL-1RA and soluble TNF receptors (p55/p75) were markedly elevated compared with normal control subjects, but showed no differences between fCTA and CTA. To summarize, no evidence was found for production and release of cytokines by monocytes during clinical high-flux bicarbonate hemodialysis, neither with complement-activating membranes nor with unfiltered dialysate. Therefore, this study sheds some doubt on the relevance of the "priming/second signal" theory for clinical practice. The data presented suggest that reluctance to prescribe the use of high-flux dialyzers, as advocated in many reports, may not be warranted.

Low polymorphonuclear cell degranulation during citrate anticoagulation: a comparison between citrate and heparin dialysis.

INTRODUCTION: Haemodialysis (HD)-induced bio-incompatibility includes alterations in both cellular elements and humoral factors. As far as polymorphonuclear (PMN) cells are concerned, an increase in both adhesion and degranulation has been reported. However, whereas increased PMN adherence and aggregation is highly linked with early transient complement activation, degranulation seems a continuous process, independent from the formation of complement degradation products. In the process of cell activation, including PMN degranulation, divalent cations (Ca2+) appear to play a pivotal role. As regionally administering citrate creates an almost Ca(2+)-free environment within the dialyser, it is tempting to speculate that Ca2+ dependent phenomena of bio-incompatibility, originating within the dialyser, can be attenuated by substituting conventional heparin for citrate. METHODS: Therefore, both anticoagulation modalities were compared in 10 stable patients, undergoing haemodialysis (HD) treatment with cellulose-triacetate membranes (CTA) only. Apart from the intracellular granule products myeloperoxidase (MPO) and lactoferrin (LF), the classical parameters of bio-incompatibility, peripheral blood neutropenia and complement activation, were measured. RESULTS: Analysis of MPO and LF gradients across the dialyser (concentration in efferent line-concentration in afferent line) suggested that degranulation is an early process, that occurs mainly within the extracorporeal circuit. Citrate abolished the release of MPO almost completely, whereas LF release was partially inhibited. Neither neutropenia, nor complement activation could be correlated with the occurrence of degranulation. CONCLUSIONS: HD-induced PMN degranulation seems largely independent from complement activation, but primarily reliant on Ca2+, at least in the case of CTA membranes.

Mechanisms of intra-dialyser granulocyte activation: a sequential dialyser elution study.

INTRODUCTION: During haemodialysis (HD), an early and transient white blood cell (WBC) reduction is noted in the peripheral blood, which has been attributed mainly to the sequestration of polymorphonuclear cells (PMN) in the pulmonary vasculature. However, WBC also adhere to the dialyser, as demonstrated before in an elution study performed after HD. In the present study, we investigated if intradialyser WBC sequestration contributes to the WBC nadir in the blood shortly after the start of HD and whether or not different mechanisms underlie PMN adherence in dialyser and lung. In addition, PMN degranulation was analysed not only in peripheral blood but also in dialyser eluates (DE). SUBJECTS AND METHODS: Dialysers were eluted after 7 1/2 (DE-7 1/2) and 180 (DE-180) min of HD in eight patients. Blood samples were taken before HD (t0), and at t7 1/2 and t180. Besides WBC count and differentiation, PMN adhesion (CD11b and CD62L) and degranulation markers (CD63 and CD66b) were assessed by flow cytometry. RESULTS: In the blood, a WBC fall was noted at t7 1/2 (from 5.8 to 4.8 x 10(9)/l; absolute about 5 x 10(9) cells). DE contained 3.0 x 10(6) cells at t7 1/2, and 57.2 x 10(6) at t180 (P = 0.015). As for CD11b, at t7 1/2 both in the blood and DE an increased expression was observed, as compared to t0 (P = 0.01); CD11b expression in DE-7 1/2 was higher than in DE-180 (P = 0.025). In contrast, CD62L showed downregulation only in DE both at t7 1/2 (mean fluorescence intensity (MFI) PB 4172 and DE-7 1/2 2353, P = 0.01), and at t180 (MFI 794, P = 0.03 versus DE-7 1/2), when compared to blood at t0. As for degranulation markers, an increase was observed in blood at t7 1/2 (MFI CD63 from 357 to 506, P = 0.02; CD66b from 507 to 794, P = 0.001), in comparison with t0. Eluted PMN at t7 1/2 showed a higher expression of CD63 than PMN in blood at t7 1/2 and DE-180 (MFI in DE-7 1/2 1280 and blood 506, P = 0.003). The expression of CD66b was increased in DE-7 1/2 (MFI 1803 versus blood 794, P = 0.01), and even more in DE-180 (MFI 2763, P = 0.002), when compared to blood. CONCLUSIONS: From these data it is concluded first, that intradialyser PMN sequestration does not contribute markedly to the WBC nadir in the circulation. Second, intradialyser PMN trapping appears to result primarily from non-adhesion-molecule-mediated factors, as indicated by an increased expression of CD11b at t7 1/2 on eluted PMN associated with low cell numbers in DE, and normalized CD11b expression at t180 associated with considerably higher cell numbers in DE. Third, HD-induced degranulation seems to be a complex phenomenon. After a rapid transient onset, characterized by an early upregulation of CD63 and CD66b on PMN leaving the dialyser, degranulation continues within the device as indicated by an additional rise in the expression of CD66b on PMN in DE-180.

Lymphocyte subsets in dialyser eluates: a new parameter of bioincompatibility?

INTRODUCTION: During haemodialysis (HD), several adverse reactions in peripheral blood can occur, which have been attributed to the bioincompatibility of the dialyser membrane. Utilizing a dialyser elution technique, we have demonstrated that polymorphonuclear cells (PMN) manifested non-membrane dependent signs of activation during HD with cellulose triacetate (CTA), cuprammonium (CU) and polysulphone (PS) membranes. In the present study, we employed this elution technique to investigate the influence of HD with these membranes on lymphocytes. METHODS: Eight patients were studied during HD with CTA, CU, and PS dialysers in a randomized crossover design. Dialyser elution was performed after 3 h of HD. Besides total leukocyte count and differentiation, lymphocyte subpopulations and activation status in peripheral blood and dialyser eluates were analysed by flow cytometry. RESULTS: Only with CU was a significant leukocyte decrease observed in peripheral blood at 30 min (P<0.001). Neither the total number of lymphocytes nor the proportion of T(CD3+) and B(CD19+) cells had markedly changed after HD with either membrane. Meanwhile, all membranes induced a relative decline in natural killer cells -NK(CD3-/CD16+/56+)- at the end of dialysis, although this was only significant for CTA (P=0.04). As for the T-lymphocyte subsets, the proportion of CD4+ cells had markedly increased after three hours of HD with all three dialysers, CTA and PS being significant (P<0.05). Dialyser eluates contained 33.8-82.2 x 10(6) cells, CTA yielding the highest cell counts. The majority (81-91%) of the eluted cells consisted of PMN dialyser eluates versus peripheral blood: P<0.05), whereas only few lymphocytes were found (4-13%, absolute 2.6 x 10(6)). Lymphocyte subpopulations in dialyser eluates were comparable to peripheral blood at t 180 in case of CTA and CU. In contrast PS eluates contained significantly fewer T-cells (37%), but more B-cells (22%) and NK-cells (30%) in comparison with peripheral blood at 180 min (peripheral blood: 79, 6 and 16% respectively; P<0.05). The expression of activation markers on T-cells (HLA-DR, CD25) in dialyser eluates was comparable with peripheral blood. Conclusions. The absolute number of lymphocytes in dialyser eluates of CTA, CU, and PS dialysers was low (mean 2.6 x 10(6)) in comparison with peripheral blood (mean 1.4 x 10(9)/l). Whereas non-selective adhesion occurred in CU and CTA dialysers, a selective adhesion pattern of lymphocyte subpopulations was observed in case of PS, suggesting a difference in bioincompatibility. Apparent T-cell activation was not noted, either in peripheral blood or in dialyser eluates. Because PMN in the dialyser eluates of three different membranes showed similar activation patterns in a previous study, we hypothesize that eluted lymphocyte, rather than PMN, represent a preferable parameter of bioincompatibility.

Ex vivo elution of hemodialyzers. An additional criterion for the assessment of bioincompatibility.

The analysis of hemodialysis (HD)-related bioincompatibility is focused mainly on phenomena observed in peripheral blood. However, since biocompatibility originates inside the dialyzer, white blood cells (WBC) adhering to the dialyzer are probably most subject to the influence of both dialyzer membrane and dialysate. In order to collect membrane-adherent cells, a reliable and reproducible elution technique was developed. After 3 h of HD, blood was returned to the patient with 0.9% NaCl. Then, dialyzers were eluted by recirculation of phosphate-buffered saline (PBS) or PBS/3 mM EDTA for 20 min, with or without prior flushing with 200 ml PBS. Finally, remaining adherent cells were collected by an afterwash with 10% trypsin. These solutions, as well as blood samples, were analyzed for WBC count, viability and differentiation. Random eluate samples were analyzed by flow cytometry, and the influence of elution on PMN activation was tested in a separate control experiment. WBC numbers decreased by flushing before elution, whereas cell numbers were maximal after elution with PBS/3 mM EDTA (30 x 10(6)). Trypsin afterwash resulted in a further yield of 12 x 10(6) cells. The eluates contained 81% PMN (blood 68%, p < 0.01), with a degranulated appearance, and only 12% lymphocytes (blood 21%, p < 0.05); cell viability in the eluates was > 95%. The eluted cells could be analyzed by flow cytometry, and the procedure itself induced only minimal PMN activation. In conclusion, a maximal number of adherent cells, consisting mainly of PMN, was obtained by direct elution with PBS/3 mM EDTA. The method itself did not induce marked PMN activation, and the cells obtained were suitable for further investigations, including flow cytometry.

Granulocyte sequestration in dialysers: a comparative elution study of three different membranes.

BACKGROUND: The present study was designed to investigate the expression of activation markers on polymorphonuclear cells (PMN) in peripheral blood and dialyser eluates, comparing three different membranes. METHODS: Eight patients were studied during HD with cellulose triacetate (CTA), cuprammonium (CU), and polysulphone (PS) dialysers in a randomized crossover design. In addition to total cell count and microscopic leukocyte differentiation, the expression of degranulation (CD63, CD66b) and adhesion (CD62L) markers on PMN was analysed in peripheral blood over time, and in dialyser eluates at the end of HD. RESULTS: In peripheral blood a significant drop in PMN was noted only during CU HD (P < 0.001), whereas none of the membranes induced any substantial change in the expression of the activation markers mentioned. In dialyser eluates the mean number of cells was 53 x 10(6), CTA yielding a significantly higher number as compared with CU (P = 0.05). The proportion of PMN was 81-91% (P < 0.05 versus peripheral blood). The expression of CD63, and especially CD66b, in dialyser eluates of all membranes was significantly higher in comparison with peripheral blood, whereas the expression of CD62L in dialyser eluates was considerably lower. CONCLUSIONS: Dialyser eluates of all three dialysers consisted mainly of PMN. Based on the relatively modest cell numbers and the expression of the activation markers described, our results suggest primarily degranulation within the dialyser. Apart from differences in cell numbers, CTA yielding the highest cell counts, no differences between CTA, CU, and PS could be demonstrated in dialyser eluates.

Biocompatibility and performance of a modified cellulosic and a synthetic high flux dialyzer. A randomized crossover comparison between cellulose triacetate and polysulphon.

The biocompatibility and performance of two high flux membranes (modified cellulosic: cellulose-triacetate (CTA), and a synthetic material: polysulphon [PS]) were assessed in 31 stable patients on hemodialysis (HD) in a randomized crossover study. Parameters evaluated included leukocytes, complement activation products C3a and C5a, cytokines, lymphocyte subpopulations, urea, creatinine, phosphate, and beta 2 microglobulin. Considering biocompatibility, the drop in the number of leukocytes was more pronounced during CTA HD compared with PS (p = 0.045), although both were low in comparison with cuprammonium dialysis in the same patients, as observed during a separate study. Both membranes induced a low and transient state of complement activation. Interleukin 1 beta and interleukin 6 could not be detected at all, whereas tumor necrosis factor alpha levels were marginally elevated before and after HD with both membranes. During the first 30 min of HD with either membrane, the numbers of CD8+ cells decreased significantly, resulting in an increase in the CD4/CD8 ratios; in addition, the number of NK cells decreased. Performance, as measured by extraction ratios for small molecular weight solutes and Kt/V urea, was significantly better during CTA dialysis (p < 0.001), but almost similar after correction for membrane surface area. On the basis of these data, it seems justified to conclude that, whereas biocompatibility of the PS dialyzer appeared slightly superior to CTA, performance of both dialyzers was comparable.

Methodology-dependent variations in reticulocyte counts using a manual and two different flow cytometric procedures.

This paper describes a comparison between the microscopic brilliant cresyl blue and the flow cytometric thiazol orange (FACScan) and auramine O (Sysmex) methods for enumeration of reticulocytes. The mean intra-assay coefficients of variation for the microscopic, FACScan and Sysmex methods were established to be 33.9 and 5% respectively. A rather poor correlation was observed between the microscopic count and both flow cytometric methods (FACScan r = 0.61; Sysmex r = 0.57). However, the correlation between the flow cytometric methods was satisfactory (r = 0.79). Reference ranges for the reticulocyte count, corresponding with the 2.5th and 97.5th percentile, were determined for the microscopic (8-30/1000), FACScan (11-27/1000) and Sysmex (8-18/1000) methods. Sysmex R-3000 methodology definitely revealed the lowest and narrowest reference range. In conclusion, because of higher reproducibility, flow cytometric analysis of reticulocytes is an attractive alternative procedure for the microscopic enumeration method.

Nephelometric measurements of human IgG subclasses and their reference ranges.

IgG subclass measurements are generally performed with the radial immunodiffusion (RID) technique. With this method, results are obtained after an incubation period of 48-72 hours. We developed nephelometric assays on the Behring Nephelometer Analyzer (BNA) that allow a quantification of IgG subclass concentrations in a large number of samples quickly (less than 15 minutes for a complete IgG subclass profile) and reproducibly (intra-assay variation 2.5-5.5%, interassay variation 3.4-6.0% and inter-lab variation 5.4-10.3%). The nephelometric method was compared with the RID technique by analyzing the IgG subclass levels in sixty selected samples. For all IgG subclasses identical results and high correlation coefficients (r > 0.93) were found. In addition, the detection limits of the nephelometric method for all four IgG subclasses were identical or lower than those of the RID technique. Furthermore, the interlab variations of the nephelometric IgG subclass assays are lower than those of the RID method. However, the major advantages of the nephelometric assay are the speed, the minimal workload (automated IgG subclass determinations) and the possibility for automated bidirectional data transmission. Recently we have established new reference ranges for the human IgG subclasses in sera of adults and children. In order to validate these reference values we have measured the IgG subclasses in sera from 112 healthy children with the nephelometric method. In 1992, more than 2000 patient sera were tested by the nephelometric assay. A predominance of IgG2 abnormality was observed. In 9.8% of these sera the IgG2 concentration was decreased. Elevated IgG2 concentrations were found in 1.9% of the sera. Furthermore, the sum of the quantitated four IgG subclasses was similar to that of total IgG (less than 20% difference).

Comparative evaluation of the pharmacia CAP system and the DPC AlaSTAT system for in vitro detection of allergen-specific IgE with the skin prick test.

Allergen-specific IgE concentrations for 6 inhalant allergens were compared in 54 subjects, using the Pharmacia CAP System and the DPC AlaSTAT System. Similar results were obtained in 91.6% of the tests. In 8% of the tests a positive score was obtained for the Pharmacia CAP System whereas a negative result was found by use of the DPC AlaSTAT System. A negative Pharmacia CAP System result combined with a positive DPC AlaSTAT System result occurred only in 0.4% of the tests. Sensitivity and specificity was established for the Pharmacia CAP System and the DPC AlaSTAT System by comparison with results of the skin prick test. Results obtained with the Pharmacia CAP System were found to be of slightly higher sensitivity than those obtained by DPC AlaSTAT System and of similar or slightly lower specificity.

The periarteriolar lymphocyte sheath in immunodeficiency T- or B-lymphocyte area?

T- and B-lymphocyte populations in peripheral lymphoid tissues occur in distinct compartments (e.g., the periarteriolar lymphocyte sheath of the splenic white pulp is a T-cell area). The authors report on two patients with severe combined immunodeficiency (SCID) and one patient with immunodeficiency after anti-T-cell treatment for rejection of a heart transplant, in which the area surrounding the central arteriole in spleen white pulp was well-populated despite T-cell deficiency (documented by, for example, severe depletion of lymph node paracortex). Immunologic phenotyping showed the B-lymphoid lineage of lymphocytes at this location. The framework in the periarteriolar area consisted of follicular dendritic cells, which are typical framework components of B-cell areas. We conclude that assessment of only conventional histopathology of the spleen in these patients leads to erroneous conclusions about the type of immunodeficiency and that immunologic phenotyping is required to document the exact nature of the deficiency.