Immunocytochemical demonstration of lymphocyte subsets and MHC class II antigen expression in synovial membranes from dogs with rheumatoid arthritis and degenerative joint disease

The study describes the distribution of canine leucocyte antigens in synovial membrane biopsies from six dogs with canine rheumatoid arthritis (CRA) and from eight dogs with osteoarthritis (OA) secondary to spontaneous rupture of the cranial cruciate ligament (CCL) (n = 5) or patellar luxation (n = 3). Synovial membranes from five dogs without evidence of joint lesions were used as control tissues. In the subsynovium of dogs with normal joints CD5+, CD4+, CD8+ and alpha beta TCR+ lymphocytes were present only in low numbers. With monoclonal antibody (mAb) to MHC class II antigen, either none or up to 20-30% of synovial lining cells were immunoreactive. Furthermore, scattered MHCII+ stromal cells were seen in the deeper subsynovial layer. In synovial membrane biopsies from dogs with CRA numerous diffusely and perivascularly distributed CD5+ lymphocytes were found in the subsynovium. CD4+ cells outnumbered CD8+ cells and were more numerous in the perivascular areas. In all the CRA cases examined, there were markedly higher numbers of alpha beta TCR+ cells compared with gamma delta TCR+ cells. With mAb to CD21, low numbers of immunoreactive lymphocytes were demonstrated. In all the CRA cases, a marked increase of MHC class II antigen expression was noted. In the majority of samples, 50% or more than 90% of the synovial lining cells were strongly MHC class II+. Throughout the subsynovial layer there were numerous MHC class II+ cells and included those with dendritic morphology and inflammatory mononuclear cells. Furthermore, marked perivascular immunoreactivity for MHC class II antigen was found. In biopsies from dogs with OA, there were markedly lower numbers of subsynovial CD5+, CD4+ and CD8+ lymphocytes. T-cells were mainly diffusely distributed. In three of the eight OA dogs examined, there was an increased percentage of synovial lining cells expressing MHC class II. The majority of OA cases had subsynovial major histocompatibility complex (MHC) class II+ cells with a dendritic morphology.     

Book review

Manual of Procedures in Quantitative Genetics, by Walter A. Becker. Second edition, 1967. Washington State University, Pullman, Washington. Price $4.00.     

The hen's egg: Shell cracking at oviposition in battery cages and its inheritance

It is known that there is much variation between individual hens and between strains of hen in (a) the incidence of egg‐shell cracking and (b) the height through which the egg is dropped at oviposition. Pilot experiments are described from which it is concluded that:

1. most cracks that occur in a battery cage are produced when the egg drops on to the floor at oviposition;

2. they are located predominantly in the two polar thirds of the shell;

3. their incidence is determined mainly by the effective mass of the cage floor, the mean drop height and the mean attitude of the eggs at emergence from the cloaca (broad or narrowpole first) ;it is affected only slightly by the mean shell thickness and the overall mean shell curvature (egg size);

4. if a hen is kept on a floor with a high effective mass, an indirect estimate of her mean drop height can be obtained quickly, easily and with high precision from observations made on her eggs after they have been laid; the observations required are the incidence of eggs with poorly formed shells, the type, location and incidence of cracks in eggs with well‐formed shells and the mean weight of the eggs;

5. the incidence of cracking on a heavy cage floor can be used to predict the incidence on a normal floor;

6. the incidence of cracking is heritable and responds rapidly to downward selection.

It is suggested that breeders should test the technique described, with a view to adopting it as a method of selecting for low crack incidence.