Orosomucoid, a2-macroglobulin and Immunoglobulins in
Serum and Pleural Effusions
PLATO P. ASSEO, M.D. AND GEORGE D. TRACOPOULOS, M.D.
The 10th Medical Unit of the Athens Chest Hospital
Sotiria, Athens, Greece
Asseo, Plato P. and Tracopoulos, George D.: Orosomucoid,
a2-macroglobulin and immunoglobulins in serum and pleural
effusions. Am J Clin Pathol 76: 437-441, 1981. Serum and
pleural fluid levels of orosomucoid, a2-macroglobulin, IgG,
IgA, and IgM were measured in 36, 29, and nine patients suffering from malignant, tuberculous, and non-malignant, noninflammatory pleural disease, respectively. Pleural fluid concentrations of the studied proteins were higher in tuberculous
effusions, but due to wide overlapping of the values, correlation with diagnosis could not be established. The ratio of the
pleural fluid to the serum concentration of the studied proteins
was below unity with the exception of three tuberculous and
one cancer patient who showed higher values of orosomucoid
in the pleural fluid. The rate of diffusion of the various proteins in the pleural fluid was inversely proportional to their
molecular weight. (Key words: Orosomucoid; a2-macroglobulin; IgG; IgA; IgM; Pleural effusion.)
to etiological diagnosis, e.g., malignant disease (Group
I), tuberculosis (Group II), and non-malignant, noninflammatory disease (Group III). Group I included 36
patients; among them were 31 with primary lung
tumors, three with metastatic pleural involvement, one
with leukemia, and one with non-Hodgkin's lymphoma. Groups II and III comprised 29 and nine patients suffering from tuberculosis and congestive
heart failure, respectively. Diagnosis of malignant
and tuberculous pleurisy was based on cytologic
examination of sputum, pleural effusion, and
bronchial secretions, bronchoscopic or closed
pleural biopsy, and demonstration of tubercle bacilli
in direct smears and/or cultures.
Pleural fluid was collected in tubes containing solid
EDTA and centrifuged for 10 min at 3000 rpm. Serum
and pleural effusion samples were assayed the day of
the collection or stored at -20°C until assayed. Orosomucoid, a 2 -macroglobulin, IgG, IgA, and IgM were
measured by single radial immunodiffusion5 using commercially available standards and immunoplates (MPartigen, LC-Partigen and Tri-Partigen; Behringwerke, Marburg, Lahn).
THE PRESENCE of pleural effusion represents one of
the most commonly encountered problems in clinical
practice. Fluid accumulation in the pleural space might
appear as a result of pulmonary, cardiac, or systemic
disease, and in most instances clinical examination and
other investigations point to the correct diagnosis. In a
percentage of cases, however, in spite of every effort,
difficulties in diagnosis and delay in treatment arise
with occasional grave consequences for the patient's
future.
Orosomucoid estimation of pleural fluid was recently
proposed as a diagnostic aid, but opinions regarding its
value differ among various investigators 1,2,3,6,8 and
further study has been suggested. 8
The aim of this study was the evaluation of orosomucoid, a 2 -macroglobulin, IgG, IgA, and IgM in
serum and pleural effusion as indices of possible diagnostic assistance in discriminating malignant, tuberculous, and non-malignant, non-inflammatory pleural
effusions.
Results
Materials and Methods
Seventy-four patients with pleural effusion were included. They were divided into three groups according
Received December 3, 1980; accepted for publication December 18, 1980.
Address reprint requests to Dr. Tracopoulos: The 10th Medical
Unit of the Athens Chest Hospital "Sotiria", Messogeion 152,
Athens, Greece.
The results are shown in Table 1.
Mean serum levels of orosomucoid were found
higher in the tuberculous group of patients (II) when
compared to the malignant (I) and the non-malignant,
non-inflammatory group (III). Application of the t-test,
after log transformation of the values, showed statistically significant differences between all three
groups of patients. Mean pleural fluid orosomucoid
concentration was 2.8 times higher in malignant than in
non-malignant, non-inflammatory effusions. Tuberculous fluids contained 1.4 and 4.0 times more orosomucoid compared to malignant and non-malignant, noninflammatory effusions, respectively. These differences
0002-9173/81/0010/0437 $00.75 © American Society of Clinical Pathologists
437
438
A.J.C.P. . October 1981
ASSEO AND TRACOPOULOS
Discussion
The differentiation between malignant and inflammatory effusions with non-invasive technics is of great importance both in respect of prognosis and treatment.
Among inflammatory diseases of the pleura, tuberculous pleurisy is still prevalent in some areas of the
world; therefore it has a major place in the differential
diagnosis of pleural disease.
Many attempts have been made in the past to identify
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were also statistically significant but considerable
overlapping of orosomucoid values existed between
the three groups of patients, both in serum and pleural
fluid (Fig. 1).
Regarding a2-macroglobulin, higher serum values
were observed in the non-malignant, non-inflammatory
group than in the tuberculous or the malignant groups
of patients. The average pleural fluid level of this protein was found to be 2.4 times higher in malignant
than in non-malignant, non-inflammatory effusions.
Furthermore, 1.5 and 3.6 times more protein was found
in tuberculous compared to malignant and to nonmalignant, non-inflammatory effusions, respectively.
Again, as in the case of orosomucoid, significant differences existed but remarkable overlapping of the
values was present (Fig. 2).
Among serum immunoglobulins, significantly lower
values of IgM were found in the malignant group compared to the other two groups. The mean levels of the
various immunoglobulins in the pleural fluid were
higher in the tuberculous than in the malignant effusions, but lower values were observed in the nonmalignant, non-inflammatory group in comparison to
the other two groups (Fig. 3). Statistical analysis of
pleural fluid immunoglobulin levels among the various
groups of patients showed significant differences, with
the exception of IgA between malignant and tuberculous groups (Table 1).
Effusion concentrations of all protein classes expressed as percentages of their corresponding serum
value were significantly lower in the non-malignant,
non-inflammatory group in c omparison to the other two
groups. Similarly, statistically significant differences
between tuberculous and malignant effusions were
found concerning orosomucoid, a2-macroglobulin,
IgA and IgM (Table 1). The rate of diffusion of the
various proteins in the pleural fluid was inversely related to their molecular weight (Fig. 4).
Quite unexpectedly, three tubercular patients and
one cancer patient had orosomucoid values in the
pleural fluid exceeding those of the serum (203 mg/dl
versus 186, 184 versus 14?!, 136 versus 132, and 93
versus 87).
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Vol. 76 • No. 4
GLOBULINS IN SERUM IN EFFUSIONS
mg/dl
SERUM
PLEURAL
FLUID
SERUM
PLEURAL
FLUID
SERUM
PLEURAL
FLUID
360-
320y
280-
240
200-
160
120-
9
>
r
80-
40
M A L I G N A N
T
TUBERCULOUS
NON-MALIGNANT
NON-INFLAMMATORY
FIG. 1. Orosomucoid in serum and pleural fluid.
the "one best test" or a set of examinations that could
effectively determine the nature of pleural effusions.
Investigative aids proposed at times included measurement in the pleural fluid of various proteins, enzymes,
carbohydrates, cancer associated proteins etc., but the
results were more or less conflicting and unrewarding.
In accordance with other studies1-2 mean levels of all
measured proteins in the present study were found significantly lower in non-malignant, non-inflammatory effusions, compared with malignant or inflammatory
ones (Table 1), but with an overlap of the values
(Figs. 1,2,3).
It was reported8 that the average orosomucoid concentration was 2.0 times higher in malignant than in
inflammatory pleural and peritoneal effusions, and 3.7
times higher than in non-malignant, non-inflammatory ones (130 mg/dl ± 13, compared to 65 ± 17 and
35 ± 4, respectively). These results were statistically
significant. In another study3 uniformly high values of
orosomucoid in the pleural fluid, higher than 108 mg/dl,
were reported as characteristic of the malignant
process; subsequently, however, orosomucoid was
found inadequate for differentiating malignant from inflammatory effusions.' In our study, in which the inflammatory group consisted entirely of tuberculous
pleural effusions, it was found, in contrast, that the
average orosomucoid concentration of the tuberculous
effusions was higher than that of the malignant and the
non-malignant, non-inflammatory ones (142.1 mg/dl
439
± 6.4, compared with 99.8 ± 6.2 and 35.9 ± 8.0, respectively). These findings were statistically significant
(Table 1) but considerable overlapping existed and no
cutoff value was present. This latter finding is also in
agreement with that of a recent report.8
Pleural fluid, in general, contained less orosomucoid
than serum. However, in three tubercular patients and
one cancer patient the reverse was true, and this discrepancy could be attributed to local production of the
protein during the course of the tuberculous inflammatory process; the cancer patient reported exhibited a
strongly positive (necrotic) tuberculin reaction to 1
TU of PPD, and the presence of concomitant tuberculosis cannot be excluded.
In contrast to Vladutiu and colleagues8 who couldn't
find measurable a2-macroglobulin in the pleural fluid
of nine patients, this protein was detected in all the
studied fluids, with values ranging from 23 to 277.5
mg/dl. The same authors reported higher values of
a2-macroglobulin in malignant effusions compared to
non-malignant ones without, however, statistically significant difference. Our study does not support this finding. In fact, it was shown that tuberculous fluids contained higher levels of a2-macroglobulin compared to
mg/d I
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0M A L I G N A N T
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FIG. 2. a2-Macroglobulin in serum and pleural fluid.
440
ASSEO AND TRACOPOULOS
A.J.C.P. . October 1981
Ig A
IgG
I gM
it
11
59
22
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MALIGNANT TIJ8ERCULOUS NON-MALIGNANT
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MALIGNANT TUBERCULOUS NON-MALIGNANT MALIGNANT TUBERCULOUS NCN-MALIGNANT
NON-INFLAMMATORY
NON-INFLAMMATORY
FIG. 3. IgG, IgA, and IgM in serum and pleural fluid.
malignant effusions (Table 1). Similarly, higher values
of a2-macroglobulin in inflammatory pleural and peritoneal effusions are reported in another study,1 although without significant difference.
Previous studies on immunoglobulins1,7 have not
shown significant differences between malignant and
inflammatory pleural effusions. Such differences were
found to exist between tuberculous and malignant fluids
concerning IgM and IgG (Table 1). Our results confirm
that of Kay and associates' who found the mean IgG
level to be significantly lower in the malignant compared with that of the inflammatory group of effusions.
These authors postulated that the low IgG levels in
malignant effusions could not be attributed to low circulating levels of this protein, although serum immunoglobulins were not estimated. Our data show
(Table 1) both lower serum levels and rate of diffusion
of IgG in malignant compared with tubercular patients; hence the lower effusion content of this immunoglobulin in malignant compared to inflammatory effusions. This statement is also valid for IgM. It is obvious that the wide overlappiiilg of the values of all three
immunoglobulins in the examined groups of effusions
renders their estimation for differential diagnostic purposes valueless.
9080-
70-
60x 50-
40-
Q:
30-
3
20-
ii
10-
MALIGNAN T
TUBERCULOU S
NON- MALIGNANT
NON- INFLAMMATORY
FIG. 4. Pleural fluid concentrations of the various proteins expressed as percentages of the serum values. Mean levels (±2SE)
are plotted in increasing value of molecular weights. (O) Orosomucoid (M.W. 44100), (D) IgG (M.W. 150000), (A) IgA (M.W. 170000
to 398000), (O) a 2 -macroglobulin (M.W. 820000), and (V) IgM
(M.W. 900000).
Vol. 76 • No. 4
GLOBULINS IN SERUM IN EFFUSIONS
The observed (inversely,proportional to their molecular weight) rate of diffusion of the studied proteins in
the pleural fluid (Fig. 4) is in agreement with that of
other studies.1:7 It was found to be constantly higher
in tuberculous than in malignant disease (Table 1), possibly reflecting severe endothelial damage during the
course of the tuberculous inflammatory process. Nonmalignant, non-inflammatory effusions showed the
lowest rate of diffusion.
According to our results no individual protein js of
value for differentiating the malignant from the inflammatory effusions. The rate of diffusion of the various
proteins—especially the macromoleculars a2-macroglobulin and IgM—could possibly be used for the separation of pleural transudates; however this can be
achieved by less costly and time consuming procedures.
441
References
1. Agostoni A, Marasini B: Orosomucoid contents of pleural and
peritoneal effusions of various etiologies. Am J Clin Pathol
67:146-148, 1977
2. Booth SN, Lakin G, Dykes PW, et al: Cancer-associated proteins in effusion fluids. J Clin Pathol 30:537-540, 1977
3. Dirat MF, Valdiguie P: Les glycoproteines des liquides
pleuraux. Clin Chim Acta 77:219-225, 1977
4. Kay AB, Smith AF, McGavin CR, et al: Immunoglobulins and
complement in pleural effusions associated with bronchogenic
carcinoma. J Clin Pathol 29:887-889, 1976
5. Mancini G, Carbonara AO, Heremans JF: Immunochemical
quantitation of antigens by single radial immunodiffusion.
Immunochemistry 2:235-254, 1965
6. Rudmann D, Chawla RK, Del Rio AE, et al: Orosomucoid
content of pleural and peritoneal effusions. J Clin Invest
54:147-155, 1974
7. Telvi L, Jaubert F, Eyquem A, et al: Study of immunoglobulins in pleura and pleural effusions. Thorax 34:389-392, 1979
8. Vladutiu AO, Adler RH, Brason FW: Diagnostic value of biochemical analysis of pleural effusions. Am J Clin Pathol 71:
210-214, 1979