Levels of serum immunoglobulins in apparently healthy children and adults in Port Harcourt, Nigeria.

Serum levels of the immunoglobulins: IgG, IgA and IgM were determined by the single radial immunodiffusion technique of Mancini in a total of 122 apparently healthy subjects consisting of 43 children (20 males; 23 females) aged 5-12 years and 79 adults (39 males; 40 females) aged 18-65 years resident in Port Harcourt, southeastern Nigeria. The effects of age and sex on the serum levels of the various immunoglobulin types were also determined. The mean values and ranges for the various immunoglobulin types are presented for both children and adults. Although, female children were found to have significantly lower mean values of IgA compared to male children (p<0.05), there were no significant differences in the mean values of both IgG and IgM between male and female children involved in the present study (p>0.05). However, female adults had significantly higher mean values of IgG and significantly lower mean values of IgA compared to male adults (p<0.05); suggesting a significant gender difference in the value of both IgG and IgA amongst adult subjects. No significant differences were observed in the mean values of any of the various types of immunoglobulin between adults and children. The present study reports mean values of the various types of immunoglobulin in apparently healthy children and adults resident in Port Harcourt, southeastern Nigeria. Significant gender differences were observed for some of the immunoglobulin types only amongst adults. Our results suggest that these gender differences amongst adults were apparently a gradual build-up from childhood. The results also confirm suggestions that levels of some immunoglobulin types seen amongst African adults may have possibly been attained during childhood. Our study could be of value since previous reports in this regard have been relatively scanty especially in this part of Nigeria.

Serum complement levels in asymptomatic Plasmodium falciparum parasitaemic children.

Twenty-eight (42%) of 67 afebrile children (mean age 6.3 +/- 3.6 years) undergoing various minor elective surgeries were slide positive for malaria parasitaemia. All infected subjects were given oral chloroquine therapy before and after blood samples were collected. Pre- and post-treatment complement (C4, C3, Bf and CH50 levels were evaluated in 15 of the subjects who had parasite densities > or = 500/microliter. These were compared with the levels in 15 age/sex-matched children who had acute malaria, as well as with the levels in 15 age/sex matched, non-infected controls. Significant consumption of C4 was observed in both the asymptomatic (p < 0.05) and symptomatic (p < 0.05) subjects. The mean serum levels of C4 were significantly higher in the asymptomatic, when compared with the symptomatic subjects (p < 0.01), and the healthy controls (p < 0.05). The distribution of classical pathway complement haemolytic titres in the groups studied was the same as that of the C4 levels. It is concluded that the forth component of the classical complement pathway may play a protective role in asymptomatic malaria.

Immune complex levels and HBs-antigenaemia in healthy Nigerians and patients with liver diseases.

Circulating immune complexes (CIC) were precipitated and assayed in the blood of 19 adult patients with liver diseases and 39 healthy adult Nigerians. The presence of hepatitis-Bs antigen (HBs-Ag) was also investigated in both the sera and CIC of both study groups. CIC levels were not significantly different in the three different liver diseases studied (acute hepatitis, chronic hepatitis and liver cirrhosis). Higher mean CIC levels which were not correlated with the presence of HBs-Ag, were found in the blood of patients, as compared to blood donors. While HBs- Ag was detected in 42.1% of patient's sera, only 12.8% of blood donor sera had detectable antigen. However, 42.1% of CIC from patients had the antigen, while 53.8% of CIC from blood donors also contained the antigen. It is suggested that the high frequency of HBs-Ag in the precipitated CIC of healthy subjects could account for the occurrence of some post-transfusion hepatitis-B infections.

Correlation between in vivo and in vitro response of chloroquine-resistant Plasmodium falciparum in Calabar, south-eastern Nigeria.

Since chloroquine-resistant Plasmodium falciparum (CRPF) has emerged in Nigeria, we monitored the susceptibility of the parasite strain to a standard chloroquine (C25) dose in our Children's Emergency Unit. Chloroquine (CQ) is the drug of choice for malaria chemotherapy in Nigeria. The WHO 7-day in vivo evaluation and Rieckmann's microtitre technique (in vitro test) were used. 33 children of mean age 4.9 years were enrolled in the study. 27 (81.8%) of the in vitro cultures were successful. 16 (59.3%) of the successful isolates still showed schizogony at CQ concentration of 5.7 pmol/well and above. 28 (84.8%) of the children completed the in vivo study. 15 (53.6%) were parasitaemic on day 7 and/or day 14 and were regarded as parasitologic failures. The isolates from 14 of these children showed corresponding in vitro resistance of CQ concentrations equal to or above 5.7 pmol/well. The proportion of RIII (= 13.3%) appears to have increased as compared to 5.9% recorded in 1987. We conclude that there appears to be a good correlation between in vivo evaluation of parasitologic failures (53.6%) and in vitro resistance (59.3%). It thus appears that CRPF is definitely increasing in South-Eastern Nigeria. This can be expected not only to complicate malaria chemotherapy in the Children's Emergency Unit of the University of Calabar Teaching Hospital, but will contribute immensely to the deterioration of malaria therapy and control in Nigeria.

Immunological studies on pre-eclampsia in Nigerian women.

Circulating immune complexes, C3b inactivator, C3 activator, C3c, C4 and C-reactive protein were assayed in 49 patients with pre-eclampsia and 35 apparently healthy pregnant Nigerian women. Pre-eclamptic women had significantly higher mean levels of circulating immune complexes, C3c and C-reactive protein. C3 activator mean level was also higher in pre-eclampsia than in normal pregnancy, C3b inactivator concentrations were greatly depressed and the mean level was also significantly lower in the pre-eclamptic group (P less than 0.001). However, C4 mean levels were the same in both groups. From the results, it is postulated that in pre-eclamptic conditions the significantly depressed levels of C3b inactivator could predispose to the persistence of deposited immune complexes in the kidneys, resulting in tissue damage. The findings also generally indicate an immunologic pathogenesis for the renal lesions in pre-eclampsia in Nigerian women.

The pathogenesis of Plasmodium falciparum-associated tissue lesions--what role for C3b receptors?

Human tissue sections from cerebral and cerebellar cortices, the liver, the stomach pylorus, the kidney and the placenta, were examined for the presence of C3b receptors. This was carried out in order to determine whether these receptors play any role in the pathological effects of malarial infections on these tissues. The sheep erythrocyte/rabbit antibody/complement system was used. C3b receptors were only detected in the kidney glomeruli, but not in the other tissues. It is suggested that during malarial infections complement may be indirectly involved in the pathogenesis of tissue damage in the organs examined by triggering the activation and participation of other body systems.

C3b inactivator in normal mice and mice infected with Plasmodium berghei berghei.

C3b inactivator levels were assayed in clean albino mice and mice infected with Plasmodium berghei berghei. Infected animals (63.1%) had low C3b inactivator levels when compared with 45% of controls with low levels. In the low titre range, infected mice had a significantly lower mean level (P less than 0.001) of the factor than controls. Conversely, in the high titre range, the mean C3b inactivator level is significantly (P less than 0.001) higher in infected than in control mice. Lower levels of the protein were associated with low grade parasitaemia, while raised levels were found in animals with higher parasitaemia. Low grade malaria parasitaemia predisposes to lowered C3b inactivator levels that would enhance persistence of deposited immune complexes, and subsequent tissue damage where C3b receptors are present.

The effect of substance(s) associated with malarial parasites on C3b inactivator.

The effects of a substance or substances associated with malarial parasites on the inhibitory role of C3b inactivator in immune adherence were investigated. The test system involved adherence of immune complexes of complement-bearing sheep erythrocytes and rabbit antibody, using human group O erythrocytes and human renal glomerular tissues as indicators. Malarial antigen and other soluble by-products of the malarial parasites, presumably present in spent culture medium, did not interfere with the inhibitory role of C3b inactivator. However, malarial pigment, both crude and purified, enhanced immune adherence in the presence of C3b inactivator. It is suggested that malarial pigment, by inhibiting the action of C3b inactivator, may play a significant role in the immunopathogenesis of renal lesions associated with malarial infections.

Malarial immunity in pregnant Nigerian women and their newborn.

The levels of malarial fluorescent antibody titers (MFAT) were estimated throughout pregnancy and at delivery in 20 urban Nigerian primigravidas who received malarial chemoprophylaxis. There was a statistically significant (p < 0.001) fall in the MFAT levels as pregnancy progressed. The mean logarithmic MFAT levels were 2.8664 +/- 0.3326 and 2.2794 +/- 0.1656 in the first and last trimesters of pregnancy, respectively. The MFAT level in the newborn was positively correlated to the maternal MFAT level at delivery (r = 0.9468; p < 0.001). If malarial prophylactics are used for a prolonged period, the maternal MFAT level will fall, leaving newborns with lowered immunity to malaria.

Studies on the immunopathology of the nephrotic syndrome associated with Plasmodium malariae. 1. Serum levels of an immune adherence inhibitor.

A comparative study of the serum levels of an immune-adherence inhibiting factor was carried out on serum samples from eighty-seven nephrotic syndrome children, twenty-eight nephrotic adults, 202 normal school children, 116 blood donors, twenty-five falciparum malaria children and 172 patients with miscellaneous diseases. Low titres (1/32 and below) of the factor were present in sera from 63.2% of the nephrotic children 60.7% of nephrotic adults and 60.0% of children malaria, as compared with 30.7% of the normal children, 25.5% of the patients with miscellaneous diseases and 41.4% of the blood donors. There is a significant difference between nephrotic children and normal children with low titres (P less than 0.05). Furthermore, 36.8% of the nephrotic children had serum titres of 1/4 or less, as compared with 6.4% of normal children. The serum factor is tentatively referred to as 'C3b-inase'. Its similarity to conglutinogen-activating factor (KAF) and its possible role in the pathogenesis of the immune-complex nephropathy of childhood nephrotic syndrome associated with malaria are discussed.

Serum immunoconglutinin levels in healthy subjects, malaria nephrosis and other conditions.

Serum immunoconglutinin (I-K) levels were estimated and compared in 189 normal school children, ninety blood donors, eight-seven nephrotic children, twenty-eight nephrotic adults, twenty-five falciparum malaria children and 126 miscellaneous patients. Low levels (1/32 or less) were recorded in 75.1% of normal school children and 68.9% of blood donors. Similarly 95.4% of nephrotic children and 71.4% of nephrotic adults had low titres. The trend was the same in other disease groups in which 88.0% of falciparum malaria children and 65.1% miscellaneous patients had low titres. The relevance of the I-K levels obtained in the study groups is discussed.