Is immunity in diabetic patients influencing the susceptibility to infections? Immunoglobulins, complement and phagocytic function in children and adolescents with type 1 diabetes mellitus.
OBJECTIVE
Previous reports suggest an increased susceptibility of diabetes patients to infections, but little information is available on possible underlying immunologic dysfunctions. The aim of this study was to evaluate humoral factors in pediatric patients with type 1 diabetes mellitus.


METHODS
There were 66 diabetic patients (39 males:27 females; 5-17 yr) classified into two groups according to levels of glycohemoglobin (limit 9%): Group C - controlled (n = 33) and Group UC - uncontrolled (n = 33). We evaluated five patients in C and six in UC who reported previous infections. Immunologic analysis included measurement of plasma concentrations of immunoglobulins (Ig), C3, and C4 levels (turbidimetry); functional hemolytic assays for complement evaluation (CPH for classical and APH for alternative pathways), quantification of C4 isotypes C4A and C4B (ELISA), phagocytosis assays, measurement of bactericidal activity against Staphylococcus aureus, as well as tests of fungicidal capacity for Candida albicans.


RESULTS
The UC Group had higher mean age, received higher insulin doses, and had higher concentrations of glycohemoglobin than the C Group. No significant differences in duration of the disease or nutritional conditions were detected between the groups. Lower IgA values in C (10/33) and lower IgG levels in UC (23/33) were detected, and there were inverse relationship with HbA1c values. Analysis of CPH, APH, C3, and C4 showed normal levels in both groups and no statistical correlation with the HbA1c. However, 9/33 children of the UC Group had decreased C3 values. C4B levels were below the normal range in 8/20 and correlated with higher HbA1c. Both phagocytic assays for S. aureus and Candida albicans were within normal limits.


CONCLUSIONS
Low IgG concentrations and to some degree reduction in C4B levels were related to impaired metabolic control. No strong link between the immunological alterations was found in diabetic patients and the occurrence of infections.
Liberatore
Raphael Del Roio
RR
Department of Pediatrics, State Medical School, São José do Rio Preto, Sao Paulo, Brazil.
Barbosa
Sonia F C
SF
Alkimin
Maria das Graças
Md
Bellinati-Pires
Raquel
R
Florido
Marlene P C
MP
Isaac
Lourdes
L
Kirschfink
Michael
M
Grumach
Anete Sevciovic
AS
D000293:Adolescent; D000917:Antibody Formation / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003176:Complement C3 / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D004198:Disease Susceptibility / Q000276:immunology*; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000097:blood; D007239:Infections / Q000276:immunology*; D008297:Male; D010587:Phagocytosis
D003176:Complement C3; D003181:Complement C4; D007136:Immunoglobulins