Frank Momburg

Differential expression of HLA-DR, HLA-DP, HLA-DQ and associated invariant chain (Ii) in normal colorectal mucosa, adenoma and carcinoma

The expression of MHC class II antigens (HLA-DR, HLA-DP and HLA-DQ) and the associated invariant chain (Ii) was studied in epithelial cells of normal colorectal mucosae, colorectal adenomas and carcinomas, using a sensitive immunoperoxidase technique with monoclonal antibodies on frozen sections. In contrast to class II antigens, Ii was detected in some normal mucosae distant from the tumour. In residual non-neoplastic mucosa adjacent to carcinomas, Ii and class II antigens were induced in the order Ii ≥HLA-DR≥HLA-DP≥HLA-DQ, the reactions being most pronounced in cases with inflammatory alteration of the crypts. In 22/37 adenomas and 77/123 carcinomas, Ii expression clearly exceeded class II antigen expression. Class II antigens were found in 20/37 adenomas and 62/123 carcinomas, mostly in a non-coordinate manner, following the above order. A detailed analysis of the expression patterns in normal and neoplastic colon epithelial cells revealed a closer association of HLA-DP with HLA-DQ than of HLA-DR with HLA-DP, or HLA-DQ.

Expression of epidermal growth factor receptor in benign and malignant primary tumours of the breast

Using the monoclonal antibody EGFR1, normal mammary gland and a series of 213 unselected primary breast tumours were investigated immunohistochemically for expression of epidermal growth factor receptor (EGFR). In normal breast EGFR was expressed in variable patterns in lobular, ductal, and myoepithelial cells. In fibroadenoma, EGFR was detectable in variable numbers of ductal and myoepithelial cells and in stromal fibroblasts. The myoepithelial compartment of 2 cystosarcomas phyllodes also expressed EGFR. Among the 197 carcinomas tested only 20.3% contained EGFR expressing tumour cells which represented a minority in 12.2%, the majority in 2.1%, and the entire neoplastic population in 6.1% of the cases. Again, non-neoplastic ductal remnants often contained EGFR positive myoepithelial and ductal cells whereas stromal fibro-blasts expressed EGFR only occasionally. We conclude that in contrast to the normal state, EGFR-expression is a rather rare phenomenon in breast carcinoma cells, positively correlated with a declining grade of differentiation (p<0.025) and at least occasionally associated with squamous metaplasia within the tumour, that EGFR expression is not exclusively restricted to cells of the epithelial lineage, and that EGFR may have other functions not related to proliferation, since it is commonly detectable in myoepithelial cells.

Intra- and extrathymic B cells in physiologic and pathologic conditions Immunohistochemical study on normal thymus and lymphofollicular hyperplasia of the thymus*' **

Normal thymuses and thymuses with lymphofollicular hyperplasia have been examined immunohistologically using immunoenzymatic single and double labelling methods and a panel of monoclonal antibodies against B lymphocyte differentiation antigens (CD19-, CD20-, CD21-, CD22-, CD23- and CD37ag) and human immunoglobulins (IgM, IgD) for the presence and localisation of B lymphocytes and cells expressing B cell differentiation antigens. The numerous hyperplastic lymph follicles which occur in the pathological condition of lymphofollicular hyperplasia of the thymus were found to originate in the extrathymic compartment of the interlobular septal space. This area was found to be blown up by the growing lymph follicles with exactly the same cellular composition as their counterparts in the peripheral lymphatic tissue. Some of the B lymphocytes expressing the immunophenotype of follicular mantle zone lymphocytes which were detected in the thymic medulla probably infiltrated through discontinuities of the border between the perivascular space and the thymic medulla. Apart from this primarily extrathymic B cell compartment, B lymphocytes and cells expressing B cell antigens were found within the thymus medulla of normal control thymuses of different ages from fetal to adult life. These cells were detected as a small subpopulation in normal fetal, juvenile and adult thymuses. Morphologically they could be subdivided into small, round lymphoid cells accounting for less than 1% of medullary lymphoid cells, and into a larger variant, asteroidally shaped because of short cytoplasmic processes. These asteroid cells were even more infrequent than the lymphoid variant. Immunophenotype (CD19ag+, CD20ag+, CD22ag+, CD37ag+, IgM+, IgD+) and morphology of the first cell type led to the conclusion that the lymphoid cells were in fact B lymphocytes. They were scattered throughout the medulla of fetal and juvenile and adult thymuses alike. The second, the asteroid cell type, constantly expressed CD20ag and inconstantly IgM, CD22ag and CD37ag; furthermore, CD23ag was detected in a subset of the asteroid cells either restricted to the perinuclear zone or expressed in the entire cytoplasma and on the plasma membrane. The asteroid cells were located in the corticomedullary region of the fetal thymuses but were randomly distributed with a tendency to Hassalls corpuscles in juvenile and adult thymuses. They often formed rosettes with non-B lymphocytes. It can be concluded that a small number of B cells and asteroid cells of still uncertain origin, but expressing B cell antigens, are constitutive elements of the fetal and adult thymic medulla. It can be assumed that the asteroid cell might represent a novel type of thymic accessory cell and that the rosetting of non-B lymphocytes around this asteroid cell might simulate or in fact be the earliest B cell interaction of maturing T cells.

Reduction or loss of HLA-A,B,C antigens in colorectal carcinoma appears not to influence survival

Primary colorectal carcinomas of an unselected group of 159 patients 126 of whom could be curatively resected were examined for the expression of MHC class I antigens with monoclonal antibody W6/32 directed against a non-polymorphic determinant of HLA-A,B,C heavy chain. One hundred and nine (68.6%) were found to express HLA-A,B,C antigens in normal quantities, 33 (20.8%) showed a substantial reduction in expression, while 17 (10%) lacked these antigens either completely or incompletely. The loss of HLA-A,B,C was inversely correlated with the degree of differentiation. The tendency of mucinous carcinomas to lack class I antigens was statistically not significant. Tumours with distant metastatic spread at the time of operation tended to be normal with respect to HLA-A,B,C expression. Within the curatively resected group, poor differentiation and mucus production were risk factors for survival as could be shown by life table analysis after a maximum follow-up of 39 months. In contrast, the mode of HLA-A,B,C expression of the primary tumour did not influence survival within this time of observation. We conclude that in spite of increasing experimental data suggesting the contrary, the presence or absence of MHC class I antigens does not seem to profoundly modify tumour biology, at least in human colorectal carcinoma.

TPA-Induced Modulation of B Cell Differentiation Antigens Defined by Monoclonal Antibodies (HD6, HD28, HD37, HD39)

B cell neoplasms, particularly chronic lymphocytic leukemias (CLL) and non-Hodgkin’s lymphomas, can be considered as monoclonal cell populations which are arrested at certain stages of normal B cell differentiation. Efforts to suspend this restriction by treatment with the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) resulted in the stimulation of terminal differentiation-like changes of the leukemic cells (1). This process was assessed by alterations in cytoplasmic and surface immunoglobulin content (2), HLA-class II antigens (3), complement receptor (4), and morphological features (5). Lately, modulations of cell surface structures after TPA stimulation, which were followed up by monoclonal antibodies specific for B cell differentiation antigens, supported the assumption that chronic lymphocytic leukemias can be induced by TPA to further maturation towards the plasma cell stage (6,7). Thus, the monitoring of TPA-induced alterations of differentiation antigens by B cell-specific antibodies could help to i) describe more precisely the reaction pattern of the respective monoclonal antibody, ii) define closer sections along the normal B cell differentiation pathway, and iii) gain information about the genetic program of the various leukemia and lymphoma types.

Monoklonale Antikörper in der Tumordiagnostik und Tumortherapie

Seit langem ist versucht worden, tumorspezifische Antikorper herzustellen. Sowohl die Spontanregression mancher Tumore, die Infiltration des Tumors mit Leukozyten als auch der Nachweis von Antikorpern im Patientenserum zeigen, das sich das Immunsystem mit dem Tumor auseinandersetzt und versucht, ihn abzustosen. Daraus wurde der, vielleicht etwas voreilige, Schlus gezogen, das es tumorspezifische Zellmembran-Antigene geben musse, die eine Unterscheidung von normalen und neoplastischen Zellen durch Antikorper erlauben. Die klassische Methode der Immunisierung von Tieren, z. B. Kaninchen, mit Tumorzellen hatte keinen uberzeugenden Erfolg. Mit Einfuhrung der neuen Technologie der Zellhybridisierung zur Herstellung monoklonaler Antikorper durch Georges Kohler und Caesar Milstein im Jahre 1975 [1] wurde wieder die Hoffnung genahrt, nun doch endlich tumorspezifische Strukturen zu entdecken. Hunderte vielleicht sogar tausende monoklonale Antikorper gegen Tumorantigene verschiedenster menschlicher Tumoren sind inzwischen beschrieben worden. Heute, 10 Jahre nach Etablierung der Hybridomtechnik, ist man nach der anfanglichen Euphorie zu einer differenzierteren Betrachtungsweise gekommen. Es herrscht allgemeine Ubereinstimmung, das es absolut tumorspezifische Antigene offenbar nicht gibt; das jedoch Antikorper gegen Differenzierungsantigene von grosem Nutzen sind. Anhand von 3 Themenkreisen sollen die Wertigkeit, aber auch die Probleme dargestellt werden, die monoklonale Antikorper in der Tumordiagnostik und -therapie haben.