Immunologic parameters of children with urinary tract infection: effects of trimethoprim-sulfamethoxazole.

In order to determine whether a deficiency in immunologic response predisposes certain children to recurrent infections of the urinary tract, four groups of children were investigated: a control group; children with extraurinary infections; children with urinary tract infections; and a group of children treated with trimethoprim-sulfamethoxazole (TMP-SMX). In none of the groups were there changes in humoral immunoglobulins, peripheral neutrophil counts, serum complement concentrations or urinary excretion of IgG, IgA, or IgM that might might predispose to infection. However, children with urinary tract infections were more likely to belong to blood group A (66.6%; expected frequency, 45%) and had a blunted thymidine uptake of their stimulated lymphocytes (RLB) when compared with children with extraurinary infection. As well, their nitroblue tetrazolium reduction (NBT) was significantly lowered and this paralleled their RLB response. We postulated a shared antigenic feature of either their renal-urinary tissue or bacterial antigen with blood group A antigen; this prevents the mounting of an effective immunologic defence. If TMP-SMX further depresses the lymphocyte response, it may be considered contraindicated in urinary tract infection. In 11 children treated with this drug we found no significant difference between their RLB and NBT responses and those of children with infections of the urinary system treated with other drugs. We conclude that TMP-SMX does not alter the immune responses in children.