There have been few studies of intestinal mucosal immunity in patients with HIV infection. Some have reported low numbers of IgA producing immunocytes in the gut mucosa but others have found normal numbers. Now researchers in Norway have demonstrated hyperactivation of intestinal B cells in patients with AIDS.

They studied 31 patients (25 men) aged 26–52 years with HIV-1 infection (25 with AIDS). Eighteen were homosexual men and eight intravenous drug users; five had acquired the infection heterosexually. Duodenal biopsy was performed on all 31 patients and specimens were examined by in situ two colour immunofluorescence staining to quantify mucosal immunoglobulin (Ig) class and subclass producing immunocytes (plasmablasts and plasma cells). Eleven healthy, HIV seronegative, age matched controls volunteered for duodenal biopsy.

The median proportions of Ig class specific duodenal immunocytes were similar in patients and controls (patients: IgA 74.6%, IgM 19.5%, IgG 3.4%; controls: IgA 74%, IgM 21%, IgG 3.4%). Among patients there was a significant increase of Ig producing cells compared with controls (175 v 120 cells per mucosal unit) due to an increase in IgA producing cells. Patients with Kaposi’s sarcoma, Pneumocystis carinii pneumonia, cryptosporidiosis, or candidiasis had the greatest numbers of IgA producing cells. The proportion of IgG1 immunocytes in relation to total IgG was also increased in the mucosa of patients (median 81.8% of IgG producing cells) compared with controls (68.4%). Patients on highly active antiretroviral therapy (HAART) had fewer IgA producing cells (median 112/mucosal unit) than patients on no antiretroviral treatment (181/mucosal unit). Patients on two nucleoside analogues had intermediate numbers of IgA producing cells (124/mucosal unit).

Patients with advanced HIV-1 infection have increased numbers of IgA and IgG1 producing cells in duodenal mucosa. This finding is particularly marked in patients with secondary infections. Treatment with HAART may reverse the changes. It is suggested that these findings could help in the development of mucosal AIDS vaccines.