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The significance of immunological aspects in lymphogranulomatosis for the pathophysiological understanding of the disease was confirmed recently. Moreover, immunologic knowledge increasingly influences diagnosis, prognosis and treatment of Hodgkin's disease. In this survey cell-markers and cell-function of subpopulations of cells, participating in the disease are described. The origin of Hodgkin's- and Reed-Sternberg-cells as well as the aetiopathogenesis of the disease are discussed.

The IgD is unique with regard to its structure, differences between species, genetic organization and behaviour in the immune response. With the successful analysis of the structure a new picture of the function has been emerged. The function of the membrane-bound IgD as a trigger receptor of B cells is qualitatively different from the mIgM. The secreted form could act as an intercellular messenger in the network regulation of the immune response. The mechanisms of the induction and maintenance of the immunological memory and tolerance remain unclear.

Remission spectroscopy in living tissues can only be performed because scattering processes induce a pronounced amount of backscattered light. New types of scattering chambers were constructed in order to investigate the angular distribution of light intensities caused by scattering events typical for living tissues. Different solutions and suspensions containing microspheres, haemoglobin molecules, erythrocytes and liver homogenate were used in order to gain basic information applicable to remission spectrophotometry in tissue. Reflection spectroscopy in biological tissues is only possible because of the scattering properties of the material under observation. Light which penetrates the sample is remitted from the tissue. The remission is caused by the scattering of the light by different biological structures and particles. This scattered light gives information about the optical properties of the particles and structures in an integral form. A scattering chamber for small sample volumes has been developed for measurements of the optical properties of various particles in suspension. Measurements of scattering diagrams from microspheres with an average diameter of 7 microns, artificial particles, haemoglobin solutions, mixtures of microspheres and haemoglobin as well as erythrocytes and mitochondria have been performed. The different optical behaviour of the measured signals is qualitatively discussed.

The Erlangen micro-lightguide spectrophotometer EMPHO 1 was designed for fast diffuse reflection (remission) spectrophotometry in small tissue volumes. The aim was to construct a compact, modular instrument with a high repetition rate which can be adapted to moving organs, e.g. the beating heart in situ, by the use of highly flexible micro-lightguides. Focusing problems, which cannot be solved when conventional optical devices such as microscopes are used in moving tissues, become negligible. A bandpass interference filter disk, which is rotated by a motor serves as a monochromating unit. One diffuse reflection spectrum in a selected wavelength domain is recorded during each revolution of the motor. Special filter disks, with spectral ranges of 400-520, 500-630, 600-1200 nm can be used for different tasks. The monochromated light is transmitted by means of a flexible fluid-lightguide to a photomultiplier tube. The electrical signal, which is proportional to the light intensity is recorded by an IBM-compatible AT. An analogue to digital converter has been developed for the AD conversion. Sampling of the spectra occurs in steps of 2 nm triggered by a decoding unit, containing an EPROM where the function between the wavelength-angular position characteristic of the filter disk is stored. A decoder wheel mounted on the same axle as the driving motor is used to program the decoder unit and to recall the wavelength position function. The decoding procedure enables a high wavelength reproducibility to be attained. The monochromating device allows a sampling velocity of 100 spectra per second. The EMPHO I has been successfully applied to experiments in the beating heart, the brain, the eye, the liver, the small intestine and the skeletal muscle of mammals. First investigations have also been performed in the heart during open heart surgery and in human skin. The apparatus has a high sampling rate and the small catchment volume allows measurements of remission spectra in tissue volumes supplied by only a few capillaries. The absolute oxygenation and the relative haemoglobin concentration can be determined by on-line computer evaluation of the recorded spectra and displayed on a screen.