In human milk we previously found catalytic antibodies (abzymes) catalyzing hydrolysis of DNA, RNA, NMP, NDP, and NTP and also phosphorylation of proteins and lipids. In the present study we have analyzed nuclease activities of antibodies in blood of women during pregnancy and lactation. Blood of healthy male and female volunteers lacked catalytically active antibodies, whereas antibodies from blood of pregnant women hydrolyzed DNA and RNA and their relative activity varied over a wide range. Relative blood abzyme activities significantly increased after delivery and at the beginning of lactation. The highest abzyme activity was observed in blood of parturient women. Although the dynamics of changes in antibody DNase activity during pregnancy was rather individual for each woman, there was a common trend in the increase in antibody activity in the first and/or third trimester of the pregnancy. The DNase activity of IgG and IgM from blood of healthy pregnant women was 4-5 times less than that from pregnant women with pronounced autoimmune thyroiditis.
Inbred Brown-Norway female rats were immunized intraperitoneally with ovalbumin (OVA) or sham-immunized 14 days before and 10 days after mating. In subsequent studies with OVA, babies fed by immunized mothers, regardless of whether they were born from immunized or sham-immunized mothers, showed suppression of IgG, IgM and IgE anti-OVA responses. In additional studies, these babies developed OX-8-positive but W3/25-negative phenotypic suppressor T-cells specific for anti-OVA antibody production. However, these regulatory cells did not react with OVA itself when tested for in vitro proliferative response to OVA. Subsequent immunization of the neonates with OVA appeared to abrogate suppression of IgG and IgM antibody responses. However, maternally induced suppression of IgE persisted and was not influenced by subsequent immunization.
Varying titres of secretory IgA antibodies to poliovirus type 1 were found previously in the milk of unvaccinated, lactating Pakistani mothers during two different years, reflecting the antigenic exposure on mucosal membranes. To study further the changes in the extent and the form of antigenic exposure reflected in the human milk, human milk samples from Pakistani, Indian, Japanese, and Swedish mothers were collected. The quality and the neutralising capacity of the antibodies was also studied. Secretory IgA, IgG, and IgM antibodies to poliovirus type 1 were determined using enzyme linked immunosorbent assay (ELISA) and relative affinity was measured in ELISA by elution with potassium thiocyanide. Microneutralisation tests were also performed. The higher secretory IgA antibody titres to poliovirus type 1 in the unvaccinated, naturally exposed Pakistani and Indian mothers' milk, compared with the Swedish and Japanese mothers, presumably reflect the epidemiological situation in these countries. Neutralising capacity and the relative antibody affinity seemed to be higher both in the Pakistani mothers and the group without natural exposure but only given inactivated poliovirus vaccine, that is the Swedish mothers, than the group meeting only live vaccine strains, that is the Japanese mothers.