Genetics of rheumatoid factor and rheumatoid arthritis

Rheumatoid serum factors are present in greater or lesser concentration in 10–40% of individuals, the titre distribution varying in different populations and being higher, as a rule, in the older age groups. Concordance between different serum factors occurs more often than would be expected by chance, and individuals with more than one factor or with a high titre of a single factor are more likely to have rheumatoid arthritis (RA).

Rheumatoid serum factors are found more often in the offspring of seropositive individuals than in persons of the same age distribution in the remainder of the population. Rheumatoid arthritis is aggregated in families independently of the rheumatoid serum factors. The aggregation is only of the severe grades with marked erosion of cartilage and bone.

It is suggested that rheumatoid serum factors may be produced by a number of different antigens and that a summation of the effect of several antigens may be important. Evidence is produced suggesting that rheumatoid arthritis may be triggered by some common respiratory infections. The more severe forms, however, appear to depend on a predisposition which may be genetically determined.

The immune response to foreign red blood cells and the participation of short-lived lymphocytes

The sequence of morphological changes in the rat spleen following SRBC injection associated with hemolysin production has been correlated with estimates of proliferative activity by splenic lymphatic tissue. Formation of new, reactive germinal centers containing macrophages which engulf nuclear debris is a prominent feature of the response. This is prevented by pretreatment of the animal with cortisol. Indirect evidence is provided that short-lived lymphocytes produced in germinal centers may be a necessary component in the induction of other cells to proliferate and differentiate into hemolysin-producing cells. The reasons are discussed for considering short-lived lymphocytes, such as those produced in the thymus, bone marrow, and germinal centers, as differing from long-lived lymphocytes capable of antibody synthesis.

Rheumatism in foundry workers

In order to investigate loss of work from rheumatic diseases in the metal trades, employees in 10 foundries were questioned. Of 325 foundry workers aged 35 to 74 years, who had worked for at least 10 years on the foundry floor, 299 were examined clinically and radiologically for evidence of rheumatic disease. Radiographs of the hands, knees, and dorsal and lumbar spine were taken as a routine, and the pelvis was included in those aged 45 and over. A comparison was made with a control series of radiographs, from men, matched for age, in a random population sample examined earlier in the town of Leigh. Rheumatic complaints in general were less frequent in the foundry workers than in the random sample, and the foundry workers less often gave a history of prolonged incapacity (three months or more) due to this cause. Radiological evidence of disc degeneration in the lumbar spine, however, was more frequent in the foundry workers than in the controls and was of greater severity. Further, the foundry workers more commonly had symptoms and signs of lumbar disc prolapse. On the other hand, the controls had more osteo-arthrosis of the hips and knees and lost more work from pain at these sites. This was associated with a difference of body habitus, obesity being less frequent in the foundry workers. Foundry workers directly exposed to hot conditions did not have less back or leg pain than those not so exposed despite a greater prevalence of disc degeneration. Measurements of air temperature, humidity, and radiant heat were made in a foundry while pouring was in progress. The air temperature rose from 18°C. to 26°C. and the humidity ranged from 70% to 54%. The mean intensity of radiation incident on the clothed surface of a foundry worker was 0·12 watt/cm.². This was compared with conditions during therapeutic exposure to radiant heat. The radiant heat under conditions of `heat therapy' varied between 0·16 and 0·37 watt/cm.². The possible influence of radiant heat on the prevalence of rheumatic complaints is discussed.

Infectious feline agranulocytosis

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