Immunoperoxidase and immunofluorescence techniques in pig tissues

[Histochemical and immunohistochemical study of the lymphoid tissue of swine: lymphatic ganglia, spleen and thymus]

Immunohistological (S-100, cIg) and enzyme histochemical (ANAE/ANBE, beta-glu, ATPase, AcP) investigations were carried out to identify lymphocyte and reticular cell subpopulations "in situ", in pig lymphoid tissue (lymph node, spleen, and thymus) of a 6 months old group, and a 6-9 days old one. By means of immunohistological techniques, in the 6 month old pigs we could detect S-100 protein (PAP), chiefly in T-areas lymphocytes, but we also found some S-100 positive lymphocytes in spleen follicles. Also S-100 protein were detected at Follicular Dendritic Cells (FDC) in lymph node and spleen; and Reticular Fibroblastic Cells (RFC) only in the first one. Finally, S-100 were noted in Hassall corpuscles (thymus), nervous fibres, and endothelial cells too. Using PAP (IgG, IgM) and IPI (IgA) techniques we could detect lymphocyte cytoplasmatic surface immunoglobulins (cIg) in lymphocytes, lymphoblastoid and plasmacytoid cells in nearly all tissue compartments. By means of histochemical techniques we could identify T-area lymphocytes ANAE/ANBE and beta-glu positives (cytoplasmatic spots) and B-area lymphocytes ATPase positive; macrophages, and polymorphonuclear eosinophiles PHNE being ANAE/ANBE and beta-glu positives (diffuse cytoplasmic stain); and Hassall corpuscles ANAE/ANBE and AcP positives. Concerning to reticular cells, we found FDC and RFC in lymphoid follicles, and Interdigitating Reticular Cells (IDC) in lymphoid diffuse tissue, with enzyme activity (all the enzymes studied) in nearly all the cases. In piglets, the immunohistological and histochemical pattern was nearly the same.

The tissue distribution of Ia- and IgM-positive cells in adult and newborn miniature pigs

Distribution of Ia- and IgM-positive cells was compared in tissues of adult and newborn miniature pigs, using indirect immunoperoxidase and immunofluorescent techniques with monoclonal antibodies. The different distribution patterns were found mainly in adult jejunum and kidney. Both IgM- and Ia-staining were ascertained in the lamina propria between the Lieberkühn crypts and in the lymphoid follicles of the jejunum. Moreover, IgM-positive cells were demonstrated in the crypts while Ia-reaction was seen in the lamina propria of the villi. In the kidney, IgM-staining was limited to the glomeruli. On the contrary, a distinct Ia-reaction was found mainly in intertubular structures. Small differences in IgM- and Ia-positive cell distribution were also noted in the mesenteric lymph nodes and in the spleen. Developmental changes of the adult distribution patterns (chiefly that of IgM-positive cells) were found in all tissues studied at 2 days of age.

Immunohistochemical evaluation of the equine endometrium during the oestrous cycle

Endometrial biopsies were obtained from four mares during consecutive oestrous cycles on the first day of oestrus, on the day when ovulation was detected, and four and eight days after ovulation. Cycle stages were confirmed by means of rectal palpation, ultrasonography and plasma progesterone determination. Immunohistochemical evaluation of the formalin fixed biopsy specimens was performed using a peroxidase anti-peroxidase technique. Immunoglobulin (Ig)A-, IgM-, IgG(Fc)- and IgG(T)-containing cells were detected in all biopsies; with IgA- and IgG(Fc)-containing cells generally predominating. There was no cyclical trend of Ig-containing cell numbers for any isotype. Free immunoglobulins of the four classes evaluated were frequently seen in luminal epithelium, glandular epithelium and secretions, and interstitium. This study of endometrial biopsies from a limited number of cycling mares suggests the presence in the equine endometrium of free and intracellular immunoglobulins of the classes A, M, G(Fc) and G(T) without any apparent cyclical trend.

Changes in malignant phenotype of a human carcinoma conditioned by growth environment

The human epidermoid carcinoma HEp3 exhibits highly malignant growth in chicken embryos that disappears progressively in cell culture. When studied by clonal analysis, loss of tumorigenicity was apparent within 20 generations and essentially complete after 40 generations in culture; affected all clones; and occurred under conditions which excluded the selection of variants based on superior growth rate in culture. Once ostensibly lost, the malignant phenotype reappeared after prolonged exposure of nontumorigenic cells to in vivo conditions. This similarly affected all clones assayed over a wide range of inoculum sizes. There was no evidence that HEp3 populations were heterogeneous with respect to tumorigenicity, or that the results were due to preferential selection of genetically determined subpopulations. It is suggested that the malignant phenotype of HEp3 is expressed in response to conditions in the physiological environment.

Immunohistochemical studies of the local immune system in the reproductive tract of the sow

Tissues from the reproductive tract of sexually mature female pigs were examined histologically using antisera to porcine IgG, IgA and IgM coupled to horseradish peroxidase. Plasma cells synthesising all three immunoglobulins were found in all regions of the tract, with IgA-producing cells as the predominant type. Larger numbers of plasma cells were found in the lower region of the tract and the number of plasma cells was raised during oestrous. Intercellular staining of immunoglobulins was also observed and was also under hormonal influence. The results indicate the presence of a local mucosal immune system in the female reproductive tract of the pig.

Immunofluorescence studies on formalin-fixed and paraffin-embedded material

In an attempt to apply immunomorphologic techniques to formalin-fixed material, various tissues were studied by indirect immunofluorescence. To minimize nonspecific background staining, formalin-fixed paraffin sections were treated with pronase prior to incubation with the antisera. This technique was published by Huang in 1975 to study hepatitis B core and surface antigen in formalin-fixed liver-tissue. Our examination demonstrate that this technique might enable the morphologist to identify immunoglobulins in formalin-fixed tissues and so to get new criteria for their diagnosis.

Immunoglobulin-producing cells in the inflammatory infiltrates of cutaneous tumors. Immunocytologic identification in situ

An immunocytochemical technique has been developed for the identification in situ of immunoglobulin-producing cells in tissues fixed in Bouin's solution and embedded in paraffin. Technical details are discussed as well as the application of the technique to the study of plasma cells in the inflammatory infiltrate around cutaneous tumors. Preliminary results have been obtained with basal cell epitheliomas, squamous cell carcinomas, and malignant melanomas. IgA-producing cells were present in all tumors. IgG-producing cells were present in variable frequency, depending on the type of tumor, and IgM-producing cells were found only in basal cell epitheliomas and squamous cell carcinomas.

[Immunofluorescence studies of experimental glomerulonephritis in formalin-fixed and paraffin-embedded material (author's transl)]

Immunofluorescence studies are an essential part of the diagnosis in glomerulonephritis. For these studies unfixed, frozen material was used only, on account of intense background staining of formalin-fixed slides. A method developed by Huang (1975) was tested on experimental glomerulonephritis. He succeeded in minimizing the background staining of formalin-fixed liver tissue with pronase-treatment. Our results show no differences in the immunofluorescence of the experimental glomerulonephritis between frozen and paraffin-embedded sections. It seems to be possible therefore to investigate a glomerulonephritis in formalin-fixed material by this method.

Immunofluorescence studies on pathologic routine material: application to malignant lymphomas

In an attempt to apply immunmorphologic techniques to pathologic routine material, malignant lymphomas of the Non-Hodgkin- and the Hodgkin-type were studied by indirect immunofluorescence. To minimize nonspecific background staining formalin fixed paraffin sections were treated with protease prior to incubation with the antisera. The usefullness of this procedure in providing additional diagnostic criteria was tested on specimens of malignant lymphomas (chronic lymphocytic leukemias, immunocytic lymphomas, plasmocytic lymphomas, centrocytic lymphomas, centroblastic-centrocyctic lymphomas, centroblastic lymphomas, immunoblastic lymphomas, lymphoblastic lymphomas of Burkitt, convoluted and unclassified type, Hodgkin's disease). In addition, cases of nonspecific lymphadenitis were studied. The discrimination of single cells particularly of the B-cell line was facilitated using immunofluorescence and different patterns were easily recognized thus aiding the diagnosis based on light microscopic criteria. In addition, preliminary evidence was obtained that lymphoblastic lymphomas categorized as "others" may be further characterized.

The respiratory tract immune system in the pig. I. Distribution of immunoglobulin-containing cells in the respiratory tract mucosa

The number of cells containing immunoglobulins A, G and M in the respiratory tract mucosa of pigs from birth to maturity was assessed using the immunoperoxidase technique. Immunoglobulin-containing cells first appeared at 6-7 days of age and rose rapidly to reach levels at 3-4 weeks similar to those in the adult. IgA-containing cells predominated at all sites in all age groups, although there were significant proportions of cells containing IgM and IgG. Our findings suggest that IgA is transported into secretions via the mixed mucoserous glands of the nasal and tracheobronchial mucosa, and that this route is also operative for colostral IgA absorbed from the gut in the baby pig.

Background staining and sensitivity of the unlabelled antibody-enzyme (PAP) method. Comparison with the peroxidase labelled antibody sandwich method using formalin fixed paraffin embedded material

The PAP procedure was compared with the peroxidase labelled antibody sandwich method and was found to be at least 20 times more sensitive. Background staining was reduced by the addition of normal swine serum to all the immune sera or by pretreating sections with it at the beginning of either method. The PAP procedure could be effectively reduced to a period of 1 hour or less.