An evaluation of serum and tissue bound immunoglobulins in prostatic diseases.DR Gahankari, KB Golhar
Dept of Surgery, Government Medical College, Nagpur, Maharashtra.
In forty-four patients with different prostatic lesions serum immunoglobulins and tissue deposited immunoglobulins were studied by single radial immunodiffusion technique, and direct immunofluorescence and immunoperoxidase (PAP) methods respectively. Serum IgM levels were found reduced only in patients with prostatic carcinomas (80% of cases) as compared to controls. Serum IgA levels showed stage dependence in prostatic carcinoma being more raised in advanced malignancy (stage C and D) than in localized ones (stage B). Localization of immunoglobulins particularly IgM, was characteristically found in stroma and lumen along with intracellular localization in prostatic carcinoma; while normal and benign lesions of prostate only showed characteristic 'necklace' pattern. Also the intensity of deposits of immunoglobulins in poorly differentiated prostatic carcinomas was markedly low as compared to well differentiated carcinomas indicating lowered local immunological response in former. In prostatitis, IgA was also found localized in lumen indicating the immunological defence against infection by secretory antibody (IgA).
Keywords: Human, Immunoglobulins, analysis,metabolism,Male, Prostatic Hyperplasia, metabolism,pathology,Prostatic Neoplasms, metabolism,pathology,Prostatitis, metabolism,pathology,Protein Binding,
Prostatic lesions are characterized by the fact that, though they are etiologically quite different, they produce similar symptom complex. These lesions, particularly prostatic carcinomas, face great difficulties in diagnosis by routine screening methods like per rectal examination, serum acid phosphatase, cystoscopy etc. due to their high false positive rates. Even needle biopsy can miss 10% of prostatic carcinoma.
Chodirkar and Tomasi found that blood and prostate formed separate immunological compartments with respect to serum immunoglobulins. They further stated that these compartments might alter in diseased states and that the estimation of these immunoglobulins could yield information of a diagnostic value. Sirkar et al studied the tissue deposited immunoglobulins by direct immunofluorescent technique and showed that there were distinct differences between malignant and other diseases of prostate.
Are these alternations in serum and tissue bound immunoglobulins consistent and are they suggestive of underlying prostatic pathology? We attempted to seek answers to these questions in the present study, by evaluating the alterations in serum and tissue bound immunoglobulins in prostatic diseases.
In 44 patients of various prostatic lesions selected for the present study, (benign prostatic hyperplasia= 21, prostatic carcinoma= 20 and prostatitis= 3 patients), serum immunoglobulins i.e. IgG, IgA and IgM were estimated by single radial immunodiffusion (SRID) technique with the help of tripartigen plates obtained from Hoechest laboratory, Germany. Controls were 20 healthy age matched males for comparison.
Formalin fixed, paraffin embedded prostatic tissues obtained by transcrectal 'Trucut' needle biopsy or prostatectomy were studied for tissue bound immunoglobulins by immunohistochemical techniques. Controls were 2 prostates removed from healthy adults on autopsy. Localization of immunoglobulins IgG, IgA, and IgM was studied by peroxidase - antiperoxidase (PAP) method as well as by direct immunofluorescence method. Reagents for both were obtained from Dakopatts, through J. Mitra and Sons, New Delhi. The procedures in short, were as follows:
The immunoperoxidase (Peroxidase-antiperoxidase-PAP) technique adopted by Burns was used which required horse radish peroxidase complex (PAP complex), rabbit antihuman IgG, IgM and IgA, and swine antirabbit immunoglobulins. Substrate used was 3'3' diabenzedine tetrahydrochloride (DAB), which gave reddish brown precipitate at the site of antigen-antibody reaction.
For direct immunofluorescence FITC conjugate antihuman antibodies and FITC conjugated IgG, IgA and IgM were used. Slides were viewed under fluophot (Nikon) fluorescent microscope for apple green fluorescence and photomicrographs were taken with attached Nikon microflex 'Fx' system on Fuji 1600 ISA film. Results were recorded as site of localization and intensity of fluorescence.
[Table - 1] shows levels of serum immunoglobulins found in normal subjects and patients with different prostatic diseases.
Of the 44 patients of prostatic lesions studied for serum immunoglobulins, reduction in serum IgM levels was observed only in prostatic carcinomas as compared to levels in controls. This was observed in majority of patients (80%) of prostatic carcinomas. Two cases in present study need special mention. In spite of strong clinical suspicion of malignancy in both (on per rectal examination), the needle biopsies were suggestive of benign hyperplasia. Both these patients had reduced serum IgM levels. They were subjected to prostatectomy and histology confirmed early prostatic carcinoma. Reduction in serum IgM level is also reported by other authors,,,. Schmidt et al, proposed that such [Table - 2] shows comparative observations of serum depression in serum IgM levels probably denotes impaired B- cell function.
Benign prostatic hyperplasia, and prostatic cancer often stand against each other in differential diagnosis of suspected prostatic lesions. In present study the difference in the serum immunoglobulin levels between both was statistically evaluated and the difference was found to be highly significant (p < 0.02) for serum lgM levels. This can be an important criterion for differentiation between the two.
Serum IgA levels were found to be more significantly raised in advanced prostatic carcinoma (stage C and D) than in localized ones. Such stage dependence was also reported by Ablin and Deture et al. However, Gursel et al 8 has found high levels of Serum IgG and IgM in stage C and D of prostatic carcinoma [Table:3]. It is said that extracapsular tumor extension stimulates the immunoglobulin production.
In both the normal prostates studied for tissue bound immunoglobulins, localization of lg was found to be in the basal cytoplasm giving a 'necklace' pattern on immunofluorescence. [Figure:1A]. In benign hyperplasia and chronic prostatitis also deposition of IgG, IgA and 19M was found in the basal cytoplasm, thus demonstrating preservation of 'necklace' pattern [Figure:1B], [Figure:2A]. In chronic prostatitis case, the deposits were also seen in lumen against IgA, probably indicating immune defence mechanism against infection [Figure:2B].
In prostatic carcinoma, particularly in well-differentiated category, the intensity of immunofluorescence was marked as compared to normal. Also characteristically, there was localization of immunoglobulins in stroma and in lumen alongwith intracellular deposition. This indicates the existence of immunologic struggle against cancer cel IS2. Similar deposits were also noted by immunoperoxidase (PAP) technique [Figure:3A], [Figure:3B].
In majority of patients with prostatic cancer, IgM was found localized around malignant zone suggesting that probably it acts as cytotoxic antibody against cancer cells. Localization of IgG was also observed in 30% cases around malignant zone. IgG in this situation probably acts as a 'blocking antibody' and interferes with complement mediated Cytotoxicity,.
In 2 cases of poorly differentiated prostatic carcinoma, the intensity of localization as seen by immunofluorescence and immunoperoxidase was markedly low as compared to well differentiated category indicating severely impaired local immunologic response in poorly differentiated prostatic cancer [Figure:4A], [Figure:4B].
We are indebted to Dr S Grover, Prof and Head, and Dr SK Bhobhate, Associate Prof, Department of Pathology, Government Medical College, Nagpur for their cooperation and technical help in the interpretation of data.
[Table - 1], [Table - 2]