Lymphocyte subpopulations and antibody levels in immunized malnourished children.

: 1. The proportions of lymphocyte subpopulations (by rosette tests) and the serum antibody levels (using haemagglutination techniques) were estimated in malnourished and well fed Nigerian children before and up to 21 d after immunization with tetanus toxoid or measles virus vaccine. 2. Significantly diminished (P less than 0.01) mean percentage T lymphocyte levels and considerably higher mean percentage null cell levels were observed in the malnourished children before immunization with either of the vaccines. 3. There was comparable in vivo increases in percentage T lymphocytes in malnourished and control children following the administration of each antigen. 4. The mean percentage B lymphocyte levels were similar in the control and malnourished children before and after the immunization. 5. There was a slight depression in the tetanus antibody levels (P greater than 0.2) but a significant diminution (P less than 0.01) in measles virus antibody concentrations in the malnourished children. 6. Rise in mean percentage T lymphocytes corresponded with the elevation in mean tetanus antibody levels in both malnourished and control children following tetanus toxoid immunization. This was however not the situation in the malnourished children following immunization with measles virus. 7. The observed depressed T lymphocyte number in malnourished children may in practice affect their handling of antigens such as measles virus in vivo.