Systemic salmonellosis is a recognized complication of sickle cell anemia (SCA). In our initial study of SCA host defences against salmonella, we evaluated the bactericidal activity of serum against Salmonella typhimurium. When compared to controls, sera from eight out of nineteen SCA patients were deficient in bactericidal function. Levels of factor B, haemolytic complement and agglutinating antibody were similar in SCA and control sera. However, abnormalities that might theoretically account for the decreased antibacterial activity were observed in many SCA sera. These abnormal findings included:(a) defective function of the alternative complement pathway (decreased bacterial killing in the presence of Mg EGTA);(b) low serum C3 concentration; and (c) decreased total iron-binding capacity (TIBC), with a resultant increase in per cent saturation of iron-binding capacity. Of these deficiencies only the abnormal alternative pathway function was significantly associated with decreased serum bactericidal activity. A suggested function of serum bactericidal activity is prevention of bacteraemia by susceptible organisms. Thus diminished serum bactericidal capacity may increase the risk of Salmonella bacteraemia in some individuals with sickle cell disease.

Twelve patients of leprosy with arthritis and 161 patients without arthritis were studied for immunological parameters like immunoglobulins (IgG, IgM, IgA), C-reactive proteins and rheumatoid factor. There was increase in the levels of IgG, IgA value in leprosy patients with and without arthritis compared to healthy control. IgM level was decreased in both the groups compared to control, but significant decrease was observed (p <.01) in patients with arthritis. C-reactive protein was significantly positive in leprosy with arthritis group (p <.01) and positive in 12 cases of leprosy without arthritis group compared to negative control group. Rheumatoid factor was present in leprosy with arthritis (16.6%) compared to both the control group and leprosy without arthritis group. This study concluded the presence of arthritis in leprosy patients as a definite entity which showed changes in immunological parameters.

Serum concentrations of immunoglobulins G, A, M and IgG subclasses were determined by single radial immunodiffusion assay in a population of sickle cell anaemia patients resident in the tropics. Fifty apparently healthy subjects of haemoglobin genotype AA, of comparable age, sex and socioeconomic status (SES), and in the same environment as the patients, were included as controls. Three indices of morbidity in SCA, namely frequency of crisis, degree of anaemia and the number of organ complications, were used to derive a severity score for each patient; and thus categorize the subjects into severity groups. Immunoglobulin levels were then correlated with the indices of morbidity as well as the derived severity score. IgG, IgA, IgM, IgG1 and IgG3 levels were significantly raised in the SCA subjects when they were compared as a group with the controls. When separated into disease severity groups, the mildly affected patients were found to have virtually normal levels of immunoglobulins. Total IgG concentration and level of the IgG3 subclass showed significant positive correlation with frequency of crisis and derived severity score. Markedly raised levels of IgG and IgG3 may be predictive of severity in sickle cell anaemia.

Serum immunoglobulin levels (IgA, IgG, and IgM) have been assayed in a representative sample of children (aged 1-7 years) with homozygous sickle cell disease and in the age/sex-matched control children with a normal haemoglobin genotype, followed from birth in a prospective cohort study. In SS disease, significant elevation of IgA occurred from the age of two years and of IgG from the age of six years. IgM levels were not significantly different in the two genotypes. The mechanisms contributing to these changes in immunoglobulins are currently unclear as is their clinical significance.

Lymphocyte stimulation, frequency of autoantibodies and concentration of immunoglobuline classes were investigated in 90 persons of 3 age-groups (5--15, 30--40 and 65--95 years of age). An age dependent decrease of MLC- and PhA-reactivity was observed. In contrast, the frequency of autoantibodies and the concentration of IgA increased with age. Individuals with a positive antinuclear factor demonstrated decreased IgA levels. No correlation between lymphocyte stimulation and autoantibody-frequency could be observed.

Lysozyme (LZM), immunoglobulins and beta 2-microglobulin concentrations were measured in the saliva of 79 patients with primary (n = 29) or secondary (n = 50) Sjögren's syndrome and in a control population. beta 2-microglobulin and immunoglobulins A, G and M concentrations were higher, and LZM concentrations lower than in controls. A significant correlation was established between LZM and immunoglobulins, but no correlation was found between immunoglobulins and beta 2-microglobulin, nor between the latter and LZM. These results indicate that salivary LZM concentration may be of value in the diagnosis of Sjögren's syndrome.