Patients characteristics and standard CSF parameters
In total, the CSF results of 108 patients from four centers were analyzed. As many patients received several lumbar punctures, a total of 316 CSF analyses were considered. The patients’ mean age was 48 years, with a range from 19 to 81 years. The underlying diagnoses included multiple sclerosis treated with natalizumab (MS/NTZ, n = 54), HIV infection (n = 25), and hematological diseases such as B-cell non-Hodgkin lymphoma (n = 10), multiple myeloma (n = 2), chronic lymphocytic leukemia (n = 6), and acute myeloid leukemia (n = 1) (referred to collectively as lymphoma group). Ten patients of the lymphoma group were treated with rituximab mono- or combination-therapy. Other chemotherapy regimens included bendamustine, melphalane, mitoxantrone, or methotrexate. In four of the patients an organ transplant had been performed and they received immunosuppressive therapy with tacrolimus, mycophenolate mofetil, or ciclosporin. One patient each suffered from bronchial carcinoma, sarcoidosis, microscopic polyangiitis and common variable immunodeficiency (CVID). In two cases no explanatory underlying disease was found. Detailed information about the individual patients can be found in supplementary table 1. Regarding the standard CSF parameter of the first lumbar puncture (Table 1), 24/108 patients (22%) had an elevated cell count and 35/108 patients showed an elevated Qalbumin indicating a disturbed blood-CSF-barrier. The mean lactate content was 1.64 mmol/l (range: 0.99–2.8 mmol/l), whereby 6/108 (6%) subjects presented with increased lactate levels.
Table 1
Standard CSF parameters of first LP (whole cohort).CSF: cerebrospinal fluid. *With an average age of the cohort of 48 years, the upper limit of Qalbumin is 7.2 (Qalbumin = 4 + (age/15).
| Standard value | Elevated (n) | Mean | Maximum | Minimum |
Cell count (cell/µl) | ≤ 4 | 24 | 5 | 34 | 1 |
Qalbumin | < 7.3* | 35 | 8.62 | 25.1 | 1.9 |
CSF protein (mg/l) | ≤ 500 | 41 | 541 | 1330 | 226 |
CSF lactate (mmol/l) | < 2.2 | 6 | 1.64 | 2.8 | 0.99 |
Comparison of PML cohort and control group
Standard CSF parameters of the whole PML cohort were compared with CSF results of an aged matched control group (suppl. table 2) consisting of patients with NPH (n = 8) or IIH (n = 13). The mean age of the control group was 50 years. In the case of CSF lactate, Qalbumin, and CSF protein there was no difference between the two groups. In contrast, the CSF mean cell count of the PML cohort was higher compared with the control group (Fig. 1).
Comparison of different groups regarding standard CSF parameters at first lumbar puncture
We then compared the PML patients with different underlying diagnoses (Fig. 2). Patients with PML due to HIV infection had a higher cell count, CSF protein, Qalbumin, and CSF lactate compared with MS patients who suffered from PML because of natalizumab treatment. Also, in comparison with the control group, the HIV PML patients showed a higher cell count, CSF lactate, CSF protein, and Qalbumin level. Other PML subgroups compared among each other and in comparison with the control group had similar standard CSF parameter.
Comparison between HIV control group and HIV-PML group
To investigate whether the differences between HIV-PML patients and the other subgroups regarding standard CSF parameters were caused by either the HIV infection itself or by the PML, the HIV-PML patients were compared with an HIV control group without PML (suppl. table 3). While there was no significant difference concerning CSF lactate, HIV-PML patients showed a significantly higher CSF cell count, CSF protein and Qalbumin compared with the
non-PML control group (Fig. 3.
Analysis of standard CSF parameters in subsequent lumbar punctures
Several patients received subsequent lumbar punctures after PML was initially diagnosed. The maximum number of lumbar punctures in one patient was 26. To investigate whether the results of CSF analysis changed over time, the average time between the first lumbar puncture and subsequent punctures was calculated. In total, up to the first 9 punctures were considered. The results of the further punctures (10 to max. 26) were not considered representative for the total cohort because of too few patients. None of the parameters changed significantly over time or in the course of subsequent punctures (Fig. 4).
CSF cell distribution in PML patients at first lumbar puncture
In 85 patients of the total cohort a differentiation of cell distribution was performed at the first lumbar puncture. Sixty-seven patients (79%) showed a lymphocytic predominance while in 10 patients (12%) the majority of cells was monocytic. Six patients (7%) exhibited a mixed cell distribution and only two patients (2%) demonstrated mainly granulocytes within the CSF. The latter is best explained by artificial blood admixture. Considering the individual subgroups, patients of the MS/NTZ-, the HIV-, the lymphoma- and the transplant-group all showed a lymphocytic predominance (Table 2). Regarding both control groups, the clear majority of patients showed a lymphocytic predominance. A certain percentage of HIV patients showed a mixed cell distribution, whereby in all of those lumbar punctures an artificial blood admixture could be observed.
Table 2
CSF cell distribution of PML subgroups. HIV: human immunodeficiency virus, MS: multiple sclerosis. Normal cell distribution is defined as 90 − 60% lymphocytes and 10–40% monocytes.
| cell count (cell/µl) | Qalbumin | protein (mg/l) | lactate (mmol/l) | lymphocytes (%) | monocytes (%) | granulocytes (%) |
only PML (n = 18) | 1.4 ± 2.7 | 6.07 ± 2.91 | 499 ± 469 | 1.58 ± 0.76 | 88.8 ± 23.1 | 18.8 ± 31.1 | 9 ± 9.2 |
IRIS (n = 26) | 3.7 ± 11.2 | 6.95 ± 8.72 | 514 ± 585 | 1.91 ± 1.13 | 77 ± 53.5 | 13.4 ± 26.5 | 28.8 ± 47.6 |
p-value | 0.052 | 0.553 | 0.849 | 0.052 | | | |
Analysis of CSF parameters of patients who were diagnosed with PML-IRIS |
Table 3: Results of initial lumbar punctures compared with subsequent CSF analyses in patients with PML-IRIS. IRIS: immune reconstitution syndrome, PML: progressive multifocal leukoencephalopathy
In 18 patients of the total cohort (16 MS/NTZ patients, 2 HIV patients) detailed information about the occurrence of an immune reconstitution syndrome (IRIS) in subsequent lumbar punctures was available. Further 23 MS/NTZ patients presented with IRIS as well, but information about subsequent lumbar punctures was insufficient. A total of 26 additional lumbar punctures that were performed in PML-IRIS patients could be used for further analysis. Results of the initial CSF analyses (only PML) were compared with those of subsequent lumbar punctures (table 3). After IRIS was diagnosed, the patients tended to exhibit a higher cell count and higher lactate values. In contrast, no differences were observed regarding the other parameters. In addition, quantitative intrathecal immunoglobulin synthesis was determined in six IRIS-patients (data not shown). Two of them suffered from HIV infection as underlying diagnosis, the others belonged to the group of MS/NTZ patients. Except for one patient, all showed new intrathecal immunoglobulin synthesis during or after IRIS.
Comparison of CSF parameters of patients with JCPyV negative PCR with JCPyV PCR positive patients
Table 4
Comparison of JCPyV PCR positive patients and JCPyV negative patients at first LP. Neg: negative, PCR: polymerase chain reaction, Pos: positive.
| cell count (cell/µl) | Qalbumin | protein (mg/l) | lactate (mmol/l) |
PCR neg (n = 19) | 5 | 8.76 | 523.4 | 1.49 |
PCR pos (n = 76) | 4.49 | 8.3 | 542.6 | 1.68 |
p-value | 0.90 | 0.78 | 0.85 | 0.035 |
At the first lumbar puncture, the result of a JCPyV PCR analysis was available in 95 of 108 patients. Nineteen patients (20%) exhibited a negative JCPyV PCR while JCPyV PCR was positive in 76 patients (80%). While the comparison of both groups revealed no significant differences regarding CSF cell count, Qalbumin, or CSF protein, PCR positive patients exhibited a significant higher CSF lactate.
Analysis of oligoclonal bands of PML patients at first lumbar puncture
At first lumbar puncture oligoclonal bands (OCB) were analyzed in 58 patients. In 22 cases (38%) OCB type 2 (OCB in CSF only) were found, of which 18 patients belonged to the MS/NTZ group and one patient each to the HIV-, lymphoma-, and transplant-group. Nine patients (16%) exhibited OCB type 3 (identical OCB in CSF and serum and additional OCB in CSF only). The majority of patients (n = 5) suffered from HIV as underlying disease, two patients had MS/NTZ and one patient each belonged to the lymphoma and transplant group. Oligoclonal bands were negative in 27 patients, with 13 patients (22%) showing type 1 OCB (no OCB) and 14 patients (24%) showing type 4 OCB (identical OCB in CSF and serum) (Fig. 5). Seven patients (26%) of the MS/NTZ group exhibited negative oligoclonal bands at first lumbar puncture. This effect might be due to the natalizumab treatment which is known to modify oligoclonal bands (Mancuso et al, Mult Scler 2014; Harrer et al, Mult Scler 2013).