Epitope specificities and quantitative and serologic aspects of monoclonal complement (C3c and C3d) antibodies.

Twenty-two monoclonal antibodies to human C3c and ten to C3d were obtained by hybridization after the immunization of mice with complement-coated human red cells and/or purified human complement components. C3c antibodies were variable in their agglutination reactions with cells coated with C3 by antibody in vitro; more consistent and potent reactions with these cells were observed with anti-C3d, and all anti-C3d reacted with red cells coated with C3 in vivo. Immunoradiometric assays were used to estimate antibody concentration, affinity, and epitope specificity. The antibody content in ascitic fluids varied from less than 0.1 mg per ml to 5.6 mg per ml. The estimated values of antibody affinities for Sepharose-coupled C3 ranged from 2.8 X 10(6) l per M to 5.0 X 10(8) l per M; on average, IgM antibodies had higher affinities than IgG antibodies. Competitive binding assays showed that the monoclonal antibodies recognized at least seven different epitopes, four on the C3c and three on the C3d fragment of C3. When the results of serologic and quantitative assays were compared, no convincing relationship was found between serologic performance and epitope specificity, antibody concentration, or affinity. IgM antibodies generally gave higher agglutination scores than IgG antibodies, and Ig class was the only useful predictor of serologic efficacy.

Maturation of human peripheral blood leukemic cells in short-term culture.

This work is a continuation of earlier studies in this laboratory (Palú et al. 1979) in which two populations of cryopreserved acute myelogenous leukaemia (AML) cells were shown to undergo progressive maturation in vitro. Twelve other populations of AML cells have since been studied and three distinct patterns of in vitro behaviour have been observed: 1. Cells which did not mature. 2. Cells which matured to the polymorph series and 3. Cells which matured to the macrophage series. Six populations of AML cells were studied both before and after cryopreservation to demonstrate that exposure to the cryopreservative agent dimethylsulphoxide (DMSO) does not influence the patterns of maturation observed. The effect of thioproline and prostaglandins A1 and A2 on maturation was also studied. It is too early to say whether any correlation between the prognosis of the AML patients and the maturation pattern of their AML cells can be established.

Reactive arthritis following asymptomatic yersinia infection.

A case of an acute asymmetrical polyarthritis occurring in a teenage boy is described. This was shown by serological tests to be secondary to a recent infection with Yersinia enterocolitica. Reactive arthritis following infection by this organism is well recognised in Scandinavia. Only recently have two cases been reported in the U.K. (1,2). This is the first reported case in Scotland and is unusual in that the initial infection was asymptomatic. Clinical improvement was associated with falling Y. enterocolitica titres and a reduction in the E.S.R. The patient was HLA B27 positive. It is suggested that all patients presenting with an acute asymmetrical polyarthritis predominantly affecting the lower limbs should be screened by stool culture and serology for recent Y. enterocolitica infection.