Summary The distribution of iron and iron binding proteins (IBP) Hodgkin's disease (HD) is a progressive disorder of' the lymphoid system often accompanied by a deficiency in cell mediated immunity (Hansen & Good, 1974;Kaplan, 1976). The depression of cell mediated immunity in HD has been related to increased activity of suppressor cells (Twomey et al., 1980;Hillinger & Herzig, 1978;Goodwin et al., 1977; Sibbett et al., 1978), the presence of circulating inhibitory factors (Siegal, 1976; Fuks et al., 1976;Moroz et al., 1977), and, in advanced disease, decreased numbers of T-cells, (Aiuti et al., 1973;Bukowski et al., 1976). De Sousa et al. (1977 have reported poor proliferative responses to phytohaemaglutinin (PHA) of peripheral blood lymphocytes from patients with HD when compared with normal controls, corrected by splenectomy. This data coupled with observations of increased T-cell percentages in the spleens from patients with HD (Kaur et al., 1974;Payne et al., 1976;Gupta, 1980) led De Sousa et al. (1977 to postulate that depressed cell immunity in the blood is a consequence of the sequestration of a particular T-cell subset in the spleen and further to suggest that this may be associated with the presence of iron binding proteins (IBP) in the cells of the reticuloendothelial system (De Sousa et al., 1978 Anomalies of iron handling by the phagocytic system in HD were first described by Beamish et al. (1972). De Sousa et al. (1977 examined iron deposition and the distribution of IBP in five spleens involved with the disease and one nonHodgkin's lymphoma control. IBP were identified by immunofluorescent staining of frozen sections and iron by Perls Prussian blue technique. These results claimed a relationship between the distribution in the spleen of iron and IBP and involvement with HD. Smithyman et al. (1979) confirmed that elevated levels of ferritin were found in frozen sections of HD spleens, but again the study was small and the frozen section technique employed gave poor morphological detail. These reports suggest a specific relationship between IBP and, or, iron and the development of a cellular defect in HD. We were doubtful that this was so and this scepticism prompted us to study the distribution of iron and IBP not only in HD but also in other disorders including non-Hodgkin's lymphomas, thalassaemia and carcinoma where the haematological changes associated with HD may not occur.We present the results of a study of splenic tissue from 63 cases of lymphoma, 49 of which were from patients with HD. Various non-lymphomatous control spleens were included in the study incorporating spleens from patients with thalassaemia, a disease with a known abnormality in iron metabolism.

The fixation and drying regimes for frozen sections and cytocentrifuge preparations for the demonstration of surface antigens, such as immunoglobulins and iron binding proteins, vary enormously between different groups of workers. A method using freeze-dried sections and acetone fixation was compared with 16 other methods of fixation and found to be the best for tissue preservation and antigen demonstration. Freeze drying was found to improve the cytological preservation of air-dried sections considerably.

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