Basement membrane
proteins laminin,
type IV collagen and aminoterminal propeptide of
type III collagen (
type III pN-collagen) are important components of extracellular matrix of normal lymph nodes; they are present in reticular fibres and in the walls of blood vessels and sinuses. We have studied the distribution of these
proteins in 45 cases of non-Hodgkin's
lymphomas representing different types of Kiel classification. Light microscopic immunohistochemistry was used on sections from
formalin fixed,
paraffin embedded biopsy specimens. Reticular cells were identified by using
antibodies against
S-100 protein, a marker for dendritic and interdigitating reticulum cells, and against
cystatin A for the demonstration of follicular dendritic reticulum cells. The findings of the immunohistochemical stainings were generally similar in the different
lymphoma types. Thus the method for the demonstration of
extracellular matrix proteins could not give obvious aid for
lymphoma classification. BM stainings proved to be efficient in the demonstration of sinuses. Marginal and medullary sinuses of the nodal cases were either totally or partly spared and open also in the cases in which there was extracapsular growth. The fibre content was variable, but generally the distribution of all the three
extracellular matrix proteins was comparable with each other and mainly corresponded with the pattern seen in conventional Gomori's
reticulin stain. This also holds for the
tumor tissue infiltrated through the
capsule and for extranodal cases. Areas of
sclerosis of some cases contained only
type III pN-collagen. Reticular fibres were at places seen to be closely associated with cells of spindle or dendritic shape. A few reticulum cells could be found to show cytoplasmic staining for
laminin,
type IV collagen and
type III pN collagen. This finding suggests that the cells are synthetizing these
proteins. The amount of cells staining for
cystatin A or
S-100 protein did not generally correlate with the amount of fibres, and most of the stained cells were not closely associated with fibres. The results show that in non-Hodgkin's
lymphomas basement membrane
proteins and
type III pN-collagen are important components of reticular fibres. Results also indirectly support the main role of fibroblastic reticulum cells in the production of the fibres.